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Raffi Hovasapian

Raffi Hovasapian

The Pentose Phosphate Pathway

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Table of Contents

Section 1: Preliminaries on Aqueous Chemistry
Aqueous Solutions & Concentration

39m 57s

Intro
0:00
Aqueous Solutions and Concentration
0:46
Definition of Solution
1:28
Example: Sugar Dissolved in Water
2:19
Example: Salt Dissolved in Water
3:04
A Solute Does Not Have to Be a Solid
3:37
A Solvent Does Not Have to Be a Liquid
5:02
Covalent Compounds
6:55
Ionic Compounds
7:39
Example: Table Sugar
9:12
Example: MgCl₂
10:40
Expressing Concentration: Molarity
13:42
Example 1
14:47
Example 1: Question
14:50
Example 1: Solution
15:40
Another Way to Express Concentration
22:01
Example 2
24:00
Example 2: Question
24:01
Example 2: Solution
24:49
Some Other Ways of Expressing Concentration
27:52
Example 3
29:30
Example 3: Question
29:31
Example 3: Solution
31:02
Dilution & Osmotic Pressure

38m 53s

Intro
0:00
Dilution
0:45
Definition of Dilution
0:46
Example 1: Question
2:08
Example 1: Basic Dilution Equation
4:20
Example 1: Solution
5:31
Example 2: Alternative Approach
12:05
Osmotic Pressure
14:34
Colligative Properties
15:02
Recall: Covalent Compounds and Soluble Ionic Compounds
17:24
Properties of Pure Water
19:42
Addition of a Solute
21:56
Osmotic Pressure: Conceptual Example
24:00
Equation for Osmotic Pressure
29:30
Example of 'i'
31:38
Example 3
32:50
More on Osmosis

29m 1s

Intro
0:00
More on Osmosis
1:25
Osmotic Pressure
1:26
Example 1: Molar Mass of Protein
5:25
Definition, Equation, and Unit of Osmolarity
13:13
Example 2: Osmolarity
15:19
Isotonic, Hypertonic, and Hypotonic
20:20
Example 3
22:20
More on Isotonic, Hypertonic, and Hypotonic
26:14
Osmosis vs. Osmotic Pressure
27:56
Acids & Bases

39m 11s

Intro
0:00
Acids and Bases
1:16
Let's Begin With H₂O
1:17
P-Scale
4:22
Example 1
6:39
pH
9:43
Strong Acids
11:10
Strong Bases
13:52
Weak Acids & Bases Overview
14:32
Weak Acids
15:49
Example 2: Phosphoric Acid
19:30
Weak Bases
24:50
Weak Base Produces Hydroxide Indirectly
25:41
Example 3: Pyridine
29:07
Acid Form and Base Form
32:02
Acid Reaction
35:50
Base Reaction
36:27
Ka, Kb, and Kw
37:14
Titrations and Buffers

41m 33s

Intro
0:00
Titrations
0:27
Weak Acid
0:28
Rearranging the Ka Equation
1:45
Henderson-Hasselbalch Equation
3:52
Fundamental Reaction of Acids and Bases
5:36
The Idea Behind a Titration
6:27
Let's Look at an Acetic Acid Solution
8:44
Titration Curve
17:00
Acetate
23:57
Buffers
26:57
Introduction to Buffers
26:58
What is a Buffer?
29:40
Titration Curve & Buffer Region
31:44
How a Buffer Works: Adding OH⁻
34:44
How a Buffer Works: Adding H⁺
35:58
Phosphate Buffer System
38:02
Example Problems with Acids, Bases & Buffers

44m 19s

Intro
0:00
Example 1
1:21
Example 1: Properties of Glycine
1:22
Example 1: Part A
3:40
Example 1: Part B
4:40
Example 2
9:02
Example 2: Question
9:03
Example 2: Total Phosphate Concentration
12:23
Example 2: Final Solution
17:10
Example 3
19:34
Example 3: Question
19:35
Example 3: pH Before
22:18
Example 3: pH After
24:24
Example 3: New pH
27:54
Example 4
30:00
Example 4: Question
30:01
Example 4: Equilibria
32:52
Example 4: 1st Reaction
38:04
Example 4: 2nd Reaction
39:53
Example 4: Final Solution
41:33
Hydrolysis & Condensation Reactions

18m 45s

Intro
0:00
Hydrolysis and Condensation Reactions
0:50
Hydrolysis
0:51
Condensation
2:42
Example 1: Hydrolysis of Ethyl Acetate
4:52
Example 2: Condensation of Acetic Acid with Ethanol
8:42
Example 3
11:18
Example 4: Formation & Hydrolysis of a Peptide Bond Between the Amino Acids Alanine & Serine
14:56
Section 2: Amino Acids & Proteins: Primary Structure
Amino Acids

38m 19s

Intro
0:00
Amino Acids
0:17
Proteins & Amino Acids
0:18
Difference Between Amino Acids
4:20
α-Carbon
7:08
Configuration in Biochemistry
10:43
L-Glyceraldehyde & Fischer Projection
12:32
D-Glyceraldehyde & Fischer Projection
15:31
Amino Acids in Biological Proteins are the L Enantiomer
16:50
L-Amino Acid
18:04
L-Amino Acids Correspond to S-Enantiomers in the RS System
20:10
Classification of Amino Acids
22:53
Amino Acids With Non-Polar R Groups
26:45
Glycine
27:00
Alanine
27:48
Valine
28:15
Leucine
28:58
Proline
31:08
Isoleucine
32:42
Methionine
33:43
Amino Acids With Aromatic R Groups
34:33
Phenylalanine
35:26
Tyrosine
36:02
Tryptophan
36:32
Amino Acids, Continued

27m 14s

Intro
0:00
Amino Acids With Positively Charged R Groups
0:16
Lysine
0:52
Arginine
1:55
Histidine
3:15
Amino Acids With Negatively Charged R Groups
6:28
Aspartate
6:58
Glutamate
8:11
Amino Acids With Uncharged, but Polar R Groups
8:50
Serine
8:51
Threonine
10:21
Cysteine
11:06
Asparagine
11:35
Glutamine
12:44
More on Amino Acids
14:18
Cysteine Dimerizes to Form Cystine
14:53
Tryptophan, Tyrosine, and Phenylalanine
19:07
Other Amino Acids
20:53
Other Amino Acids: Hydroxy Lysine
22:34
Other Amino Acids: r-Carboxy Glutamate
25:37
Acid/Base Behavior of Amino Acids

48m 28s

Intro
0:00
Acid/Base Behavior of Amino Acids
0:27
Acid/Base Behavior of Amino Acids
0:28
Let's Look at Alanine
1:57
Titration of Acidic Solution of Alanine with a Strong Base
2:51
Amphoteric Amino Acids
13:24
Zwitterion & Isoelectric Point
16:42
Some Amino Acids Have 3 Ionizable Groups
20:35
Example: Aspartate
24:44
Example: Tyrosine
28:50
Rule of Thumb
33:04
Basis for the Rule
35:59
Example: Describe the Degree of Protonation for Each Ionizable Group
38:46
Histidine is Special
44:58
Peptides & Proteins

45m 18s

Intro
0:00
Peptides and Proteins
0:15
Introduction to Peptides and Proteins
0:16
Formation of a Peptide Bond: The Bond Between 2 Amino Acids
1:44
Equilibrium
7:53
Example 1: Build the Following Tripeptide Ala-Tyr-Ile
9:48
Example 1: Shape Structure
15:43
Example 1: Line Structure
17:11
Peptides Bonds
20:08
Terms We'll Be Using Interchangeably
23:14
Biological Activity & Size of a Peptide
24:58
Multi-Subunit Proteins
30:08
Proteins and Prosthetic Groups
32:13
Carbonic Anhydrase
37:35
Primary, Secondary, Tertiary, and Quaternary Structure of Proteins
40:26
Amino Acid Sequencing of a Peptide Chain

42m 47s

Intro
0:00
Amino Acid Sequencing of a Peptide Chain
0:30
Amino Acid Sequence and Its Structure
0:31
Edman Degradation: Overview
2:57
Edman Degradation: Reaction - Part 1
4:58
Edman Degradation: Reaction - Part 2
10:28
Edman Degradation: Reaction - Part 3
13:51
Mechanism Step 1: PTC (Phenylthiocarbamyl) Formation
19:01
Mechanism Step 2: Ring Formation & Peptide Bond Cleavage
23:03
Example: Write Out the Edman Degradation for the Tripeptide Ala-Tyr-Ser
30:29
Step 1
30:30
Step 2
34:21
Step 3
36:56
Step 4
38:28
Step 5
39:24
Step 6
40:44
Sequencing Larger Peptides & Proteins

1h 2m 33s

Intro
0:00
Sequencing Larger Peptides and Proteins
0:28
Identifying the N-Terminal Amino Acids With the Reagent Fluorodinitrobenzene (FDNB)
0:29
Sequencing Longer Peptides & Proteins Overview
5:54
Breaking Peptide Bond: Proteases and Chemicals
8:16
Some Enzymes/Chemicals Used for Fragmentation: Trypsin
11:14
Some Enzymes/Chemicals Used for Fragmentation: Chymotrypsin
13:02
Some Enzymes/Chemicals Used for Fragmentation: Cyanogen Bromide
13:28
Some Enzymes/Chemicals Used for Fragmentation: Pepsin
13:44
Cleavage Location
14:04
Example: Chymotrypsin
16:44
Example: Pepsin
18:17
More on Sequencing Larger Peptides and Proteins
19:29
Breaking Disulfide Bonds: Performic Acid
26:08
Breaking Disulfide Bonds: Dithiothreitol Followed by Iodoacetate
31:04
Example: Sequencing Larger Peptides and Proteins
37:03
Part 1 - Breaking Disulfide Bonds, Hydrolysis and Separation
37:04
Part 2 - N-Terminal Identification
44:16
Part 3 - Sequencing Using Pepsin
46:43
Part 4 - Sequencing Using Cyanogen Bromide
52:02
Part 5 - Final Sequence
56:48
Peptide Synthesis (Merrifield Process)

49m 12s

Intro
0:00
Peptide Synthesis (Merrifield Process)
0:31
Introduction to Synthesizing Peptides
0:32
Merrifield Peptide Synthesis: General Scheme
3:03
So What Do We Do?
6:07
Synthesis of Protein in the Body Vs. The Merrifield Process
7:40
Example: Synthesis of Ala-Gly-Ser
9:21
Synthesis of Ala-Gly-Ser: Reactions Overview
11:41
Synthesis of Ala-Gly-Ser: Reaction 1
19:34
Synthesis of Ala-Gly-Ser: Reaction 2
24:34
Synthesis of Ala-Gly-Ser: Reaction 3
27:34
Synthesis of Ala-Gly-Ser: Reaction 4 & 4a
28:48
Synthesis of Ala-Gly-Ser: Reaction 5
33:38
Synthesis of Ala-Gly-Ser: Reaction 6
36:45
Synthesis of Ala-Gly-Ser: Reaction 7 & 7a
37:44
Synthesis of Ala-Gly-Ser: Reaction 8
39:47
Synthesis of Ala-Gly-Ser: Reaction 9 & 10
43:23
Chromatography: Eluent, Stationary Phase, and Eluate
45:55
More Examples with Amino Acids & Peptides

54m 31s

Intro
0:00
Example 1
0:22
Data
0:23
Part A: What is the pI of Serine & Draw the Correct Structure
2:11
Part B: How Many mL of NaOH Solution Have Been Added at This Point (pI)?
5:27
Part C: At What pH is the Average Charge on Serine
10:50
Part D: Draw the Titration Curve for This Situation
14:50
Part E: The 10 mL of NaOH Added to the Solution at the pI is How Many Equivalents?
17:35
Part F: Serine Buffer Solution
20:22
Example 2
23:04
Data
23:05
Part A: Calculate the Minimum Molar Mass of the Protein
25:12
Part B: How Many Tyr Residues in this Protein?
28:34
Example 3
30:08
Question
30:09
Solution
34:30
Example 4
48:46
Question
48:47
Solution
49:50
Section 3: Proteins: Secondary, Tertiary, and Quaternary Structure
Alpha Helix & Beta Conformation

50m 52s

Intro
0:00
Alpha Helix and Beta Conformation
0:28
Protein Structure Overview
0:29
Weak interactions Among the Amino Acid in the Peptide Chain
2:11
Two Principals of Folding Patterns
4:56
Peptide Bond
7:00
Peptide Bond: Resonance
9:46
Peptide Bond: φ Bond & ψ Bond
11:22
Secondary Structure
15:08
α-Helix Folding Pattern
17:28
Illustration 1: α-Helix Folding Pattern
19:22
Illustration 2: α-Helix Folding Pattern
21:39
β-Sheet
25:16
β-Conformation
26:04
Parallel & Anti-parallel
28:44
Parallel β-Conformation Arrangement of the Peptide Chain
30:12
Putting Together a Parallel Peptide Chain
35:16
Anti-Parallel β-Conformation Arrangement
37:42
Tertiary Structure
45:03
Quaternary Structure
45:52
Illustration 3: Myoglobin Tertiary Structure & Hemoglobin Quaternary Structure
47:13
Final Words on Alpha Helix and Beta Conformation
48:34
Section 4: Proteins: Function
Protein Function I: Ligand Binding & Myoglobin

51m 36s

Intro
0:00
Protein Function I: Ligand Binding & Myoglobin
0:30
Ligand
1:02
Binding Site
2:06
Proteins are Not Static or Fixed
3:36
Multi-Subunit Proteins
5:46
O₂ as a Ligand
7:21
Myoglobin, Protoporphyrin IX, Fe ²⁺, and O₂
12:54
Protoporphyrin Illustration
14:25
Myoglobin With a Heme Group Illustration
17:02
Fe²⁺ has 6 Coordination Sites & Binds O₂
18:10
Heme
19:44
Myoglobin Overview
22:40
Myoglobin and O₂ Interaction
23:34
Keq or Ka & The Measure of Protein's Affinity for Its Ligand
26:46
Defining α: Fraction of Binding Sites Occupied
32:52
Graph: α vs. [L]
37:33
For The Special Case of α = 0.5
39:01
Association Constant & Dissociation Constant
43:54
α & Kd
45:15
Myoglobin's Binding of O₂
48:20
Protein Function II: Hemoglobin

1h 3m 36s

Intro
0:00
Protein Function II: Hemoglobin
0:14
Hemoglobin Overview
0:15
Hemoglobin & Its 4 Subunits
1:22
α and β Interactions
5:18
Two Major Conformations of Hb: T State (Tense) & R State (Relaxed)
8:06
Transition From The T State to R State
12:03
Binding of Hemoglobins & O₂
14:02
Binding Curve
18:32
Hemoglobin in the Lung
27:28
Signoid Curve
30:13
Cooperative Binding
32:25
Hemoglobin is an Allosteric Protein
34:26
Homotropic Allostery
36:18
Describing Cooperative Binding Quantitatively
38:06
Deriving The Hill Equation
41:52
Graphing the Hill Equation
44:43
The Slope and Degree of Cooperation
46:25
The Hill Coefficient
49:48
Hill Coefficient = 1
51:08
Hill Coefficient < 1
55:55
Where the Graph Hits the x-axis
56:11
Graph for Hemoglobin
58:02
Protein Function III: More on Hemoglobin

1h 7m 16s

Intro
0:00
Protein Function III: More on Hemoglobin
0:11
Two Models for Cooperative Binding: MWC & Sequential Model
0:12
MWC Model
1:31
Hemoglobin Subunits
3:32
Sequential Model
8:00
Hemoglobin Transports H⁺ & CO₂
17:23
Binding Sites of H⁺ and CO₂
19:36
CO₂ is Converted to Bicarbonate
23:28
Production of H⁺ & CO₂ in Tissues
27:28
H⁺ & CO₂ Binding are Inversely Related to O₂ Binding
28:31
The H⁺ Bohr Effect: His¹⁴⁶ Residue on the β Subunits
33:31
Heterotropic Allosteric Regulation of O₂ Binding by 2,3-Biphosphoglycerate (2,3 BPG)
39:53
Binding Curve for 2,3 BPG
56:21
Section 5: Enzymes
Enzymes I

41m 38s

Intro
0:00
Enzymes I
0:38
Enzymes Overview
0:39
Cofactor
4:38
Holoenzyme
5:52
Apoenzyme
6:40
Riboflavin, FAD, Pyridoxine, Pyridoxal Phosphate Structures
7:28
Carbonic Anhydrase
8:45
Classification of Enzymes
9:55
Example: EC 1.1.1.1
13:04
Reaction of Oxidoreductases
16:23
Enzymes: Catalysts, Active Site, and Substrate
18:28
Illustration of Enzymes, Substrate, and Active Site
27:22
Catalysts & Activation Energies
29:57
Intermediates
36:00
Enzymes II

44m 2s

Intro
0:00
Enzymes II: Transitions State, Binding Energy, & Induced Fit
0:18
Enzymes 'Fitting' Well With The Transition State
0:20
Example Reaction: Breaking of a Stick
3:40
Another Energy Diagram
8:20
Binding Energy
9:48
Enzymes Specificity
11:03
Key Point: Optimal Interactions Between Substrate & Enzymes
15:15
Induced Fit
16:25
Illustrations: Induced Fit
20:58
Enzymes II: Catalytic Mechanisms
22:17
General Acid/Base Catalysis
23:56
Acid Form & Base Form of Amino Acid: Glu &Asp
25:26
Acid Form & Base Form of Amino Acid: Lys & Arg
26:30
Acid Form & Base Form of Amino Acid: Cys
26:51
Acid Form & Base Form of Amino Acid: His
27:30
Acid Form & Base Form of Amino Acid: Ser
28:16
Acid Form & Base Form of Amino Acid: Tyr
28:30
Example: Phosphohexose Isomerase
29:20
Covalent Catalysis
34:19
Example: Glyceraldehyde 3-Phosphate Dehydrogenase
35:34
Metal Ion Catalysis: Isocitrate Dehydrogenase
38:45
Function of Mn²⁺
42:15
Enzymes III: Kinetics

56m 40s

Intro
0:00
Enzymes III: Kinetics
1:40
Rate of an Enzyme-Catalyzed Reaction & Substrate Concentration
1:41
Graph: Substrate Concentration vs. Reaction Rate
10:43
Rate At Low and High Substrate Concentration
14:26
Michaelis & Menten Kinetics
20:16
More On Rate & Concentration of Substrate
22:46
Steady-State Assumption
26:02
Rate is Determined by How Fast ES Breaks Down to Product
31:36
Total Enzyme Concentration: [Et] = [E] + [ES]
35:35
Rate of ES Formation
36:44
Rate of ES Breakdown
38:40
Measuring Concentration of Enzyme-Substrate Complex
41:19
Measuring Initial & Maximum Velocity
43:43
Michaelis & Menten Equation
46:44
What Happens When V₀ = (1/2) Vmax?
49:12
When [S] << Km
53:32
When [S] >> Km
54:44
Enzymes IV: Lineweaver-Burk Plots

20m 37s

Intro
0:00
Enzymes IV: Lineweaver-Burk Plots
0:45
Deriving The Lineweaver-Burk Equation
0:46
Lineweaver-Burk Plots
3:55
Example 1: Carboxypeptidase A
8:00
More on Km, Vmax, and Enzyme-catalyzed Reaction
15:54
Enzymes V: Enzyme Inhibition

51m 37s

Intro
0:00
Enzymes V: Enzyme Inhibition Overview
0:42
Enzyme Inhibitors Overview
0:43
Classes of Inhibitors
2:32
Competitive Inhibition
3:08
Competitive Inhibition
3:09
Michaelis & Menten Equation in the Presence of a Competitive Inhibitor
7:40
Double-Reciprocal Version of the Michaelis & Menten Equation
14:48
Competitive Inhibition Graph
16:37
Uncompetitive Inhibition
19:23
Uncompetitive Inhibitor
19:24
Michaelis & Menten Equation for Uncompetitive Inhibition
22:10
The Lineweaver-Burk Equation for Uncompetitive Inhibition
26:04
Uncompetitive Inhibition Graph
27:42
Mixed Inhibition
30:30
Mixed Inhibitor
30:31
Double-Reciprocal Version of the Equation
33:34
The Lineweaver-Burk Plots for Mixed Inhibition
35:02
Summary of Reversible Inhibitor Behavior
38:00
Summary of Reversible Inhibitor Behavior
38:01
Note: Non-Competitive Inhibition
42:22
Irreversible Inhibition
45:15
Irreversible Inhibition
45:16
Penicillin & Transpeptidase Enzyme
46:50
Enzymes VI: Regulatory Enzymes

51m 23s

Intro
0:00
Enzymes VI: Regulatory Enzymes
0:45
Regulatory Enzymes Overview
0:46
Example: Glycolysis
2:27
Allosteric Regulatory Enzyme
9:19
Covalent Modification
13:08
Two Other Regulatory Processes
16:28
Allosteric Regulation
20:58
Feedback Inhibition
25:12
Feedback Inhibition Example: L-Threonine → L-Isoleucine
26:03
Covalent Modification
27:26
Covalent Modulators: -PO₃²⁻
29:30
Protein Kinases
31:59
Protein Phosphatases
32:47
Addition/Removal of -PO₃²⁻ and the Effect on Regulatory Enzyme
33:36
Phosphorylation Sites of a Regulatory Enzyme
38:38
Proteolytic Cleavage
41:48
Zymogens: Chymotrypsin & Trypsin
43:58
Enzymes That Use More Than One Regulatory Process: Bacterial Glutamine Synthetase
48:59
Why The Complexity?
50:27
Enzymes VII: Km & Kcat

54m 49s

Intro
0:00
Km
1:48
Recall the Michaelis–Menten Equation
1:49
Km & Enzyme's Affinity
6:18
Rate Forward, Rate Backward, and Equilibrium Constant
11:08
When an Enzyme's Affinity for Its Substrate is High
14:17
More on Km & Enzyme Affinity
17:29
The Measure of Km Under Michaelis–Menten kinetic
23:19
Kcat (First-order Rate Constant or Catalytic Rate Constant)
24:10
Kcat: Definition
24:11
Kcat & The Michaelis–Menten Postulate
25:18
Finding Vmax and [Et}
27:27
Units for Vmax and Kcat
28:26
Kcat: Turnover Number
28:55
Michaelis–Menten Equation
32:12
Km & Kcat
36:37
Second Order Rate Equation
36:38
(Kcat)/(Km): Overview
39:22
High (Kcat)/(Km)
40:20
Low (Kcat)/(Km)
43:16
Practical Big Picture
46:28
Upper Limit to (Kcat)/(Km)
48:56
More On Kcat and Km
49:26
Section 6: Carbohydrates
Monosaccharides

1h 17m 46s

Intro
0:00
Monosaccharides
1:49
Carbohydrates Overview
1:50
Three Major Classes of Carbohydrates
4:48
Definition of Monosaccharides
5:46
Examples of Monosaccharides: Aldoses
7:06
D-Glyceraldehyde
7:39
D-Erythrose
9:00
D-Ribose
10:10
D-Glucose
11:20
Observation: Aldehyde Group
11:54
Observation: Carbonyl 'C'
12:30
Observation: D & L Naming System
12:54
Examples of Monosaccharides: Ketose
16:54
Dihydroxy Acetone
17:28
D-Erythrulose
18:30
D-Ribulose
19:49
D-Fructose
21:10
D-Glucose Comparison
23:18
More information of Ketoses
24:50
Let's Look Closer at D-Glucoses
25:50
Let's Look At All the D-Hexose Stereoisomers
31:22
D-Allose
32:20
D-Altrose
33:01
D-Glucose
33:39
D-Gulose
35:00
D-Mannose
35:40
D-Idose
36:42
D-Galactose
37:14
D-Talose
37:42
Epimer
40:05
Definition of Epimer
40:06
Example of Epimer: D-Glucose, D-Mannose, and D-Galactose
40:57
Hemiacetal or Hemiketal
44:36
Hemiacetal/Hemiketal Overview
45:00
Ring Formation of the α and β Configurations of D-Glucose
50:52
Ring Formation of the α and β Configurations of Fructose
1:01:39
Haworth Projection
1:07:34
Pyranose & Furanose Overview
1:07:38
Haworth Projection: Pyranoses
1:09:30
Haworth Projection: Furanose
1:14:56
Hexose Derivatives & Reducing Sugars

37m 6s

Intro
0:00
Hexose Derivatives
0:15
Point of Clarification: Forming a Cyclic Sugar From a Linear Sugar
0:16
Let's Recall the α and β Anomers of Glucose
8:42
α-Glucose
10:54
Hexose Derivatives that Play Key Roles in Physiology Progression
17:38
β-Glucose
18:24
β-Glucosamine
18:48
N-Acetyl-β-Glucosamine
20:14
β-Glucose-6-Phosphate
22:22
D-Gluconate
24:10
Glucono-δ-Lactone
26:33
Reducing Sugars
29:50
Reducing Sugars Overview
29:51
Reducing Sugars Example: β-Galactose
32:36
Disaccharides

43m 32s

Intro
0:00
Disaccharides
0:15
Disaccharides Overview
0:19
Examples of Disaccharides & How to Name Them
2:49
Disaccharides Trehalose Overview
15:46
Disaccharides Trehalose: Flip
20:52
Disaccharides Trehalose: Spin
28:36
Example: Draw the Structure
33:12
Polysaccharides

39m 25s

Intro
0:00
Recap Example: Draw the Structure of Gal(α1↔β1)Man
0:38
Polysaccharides
9:46
Polysaccharides Overview
9:50
Homopolysaccharide
13:12
Heteropolysaccharide
13:47
Homopolysaccharide as Fuel Storage
16:23
Starch Has Two Types of Glucose Polymer: Amylose
17:10
Starch Has Two Types of Glucose Polymer: Amylopectin
18:04
Polysaccharides: Reducing End & Non-Reducing End
19:30
Glycogen
20:06
Examples: Structures of Polysaccharides
21:42
Let's Draw an (α1→4) & (α1→6) of Amylopectin by Hand.
28:14
More on Glycogen
31:17
Glycogen, Concentration, & The Concept of Osmolarity
35:16
Polysaccharides, Part 2

44m 15s

Intro
0:00
Polysaccharides
0:17
Example: Cellulose
0:34
Glycoside Bond
7:25
Example Illustrations
12:30
Glycosaminoglycans Part 1
15:55
Glycosaminoglycans Part 2
18:34
Glycosaminoglycans & Sulfate Attachments
22:42
β-D-N-Acetylglucosamine
24:49
β-D-N-AcetylGalactosamine
25:42
β-D-Glucuronate
26:44
β-L-Iduronate
27:54
More on Sulfate Attachments
29:49
Hylarunic Acid
32:00
Hyaluronates
39:32
Other Glycosaminoglycans
40:46
Glycoconjugates

44m 23s

Intro
0:00
Glycoconjugates
0:24
Overview
0:25
Proteoglycan
2:53
Glycoprotein
5:20
Glycolipid
7:25
Proteoglycan vs. Glycoprotein
8:15
Cell Surface Diagram
11:17
Proteoglycan Common Structure
14:24
Example: Chondroitin-4-Sulfate
15:06
Glycoproteins
19:50
The Monomers that Commonly Show Up in The Oligo Portions of Glycoproteins
28:02
N-Acetylneuraminic Acid
31:17
L-Furose
32:37
Example of an N-Linked Oligosaccharide
33:21
Cell Membrane Structure
36:35
Glycolipids & Lipopolysaccharide
37:22
Structure Example
41:28
More Example Problems with Carbohydrates

40m 22s

Intro
0:00
Example 1
1:09
Example 2
2:34
Example 3
5:12
Example 4
16:19
Question
16:20
Solution
17:25
Example 5
24:18
Question
24:19
Structure of 2,3-Di-O-Methylglucose
26:47
Part A
28:11
Part B
33:46
Section 7: Lipids
Fatty Acids & Triacylglycerols

54m 55s

Intro
0:00
Fatty Acids
0:32
Lipids Overview
0:34
Introduction to Fatty Acid
3:18
Saturated Fatty Acid
6:13
Unsaturated or Polyunsaturated Fatty Acid
7:07
Saturated Fatty Acid Example
7:46
Unsaturated Fatty Acid Example
9:06
Notation Example: Chain Length, Degree of Unsaturation, & Double Bonds Location of Fatty Acid
11:56
Example 1: Draw the Structure
16:18
Example 2: Give the Shorthand for cis,cis-5,8-Hexadecadienoic Acid
20:12
Example 3
23:12
Solubility of Fatty Acids
25:45
Melting Points of Fatty Acids
29:40
Triacylglycerols
34:13
Definition of Triacylglycerols
34:14
Structure of Triacylglycerols
35:08
Example: Triacylglycerols
40:23
Recall Ester Formation
43:57
The Body's Primary Fuel-Reserves
47:22
Two Primary Advantages to Storing Energy as Triacylglycerols Instead of Glycogen: Number 1
49:24
Two Primary Advantages to Storing Energy as Triacylglycerols Instead of Glycogen: Number 2
51:54
Membrane Lipids

38m 51s

Intro
0:00
Membrane Lipids
0:26
Definition of Membrane Lipids
0:27
Five Major Classes of Membrane Lipids
2:38
Glycerophospholipids
5:04
Glycerophospholipids Overview
5:05
The X Group
8:05
Example: Phosphatidyl Ethanolamine
10:51
Example: Phosphatidyl Choline
13:34
Phosphatidyl Serine
15:16
Head Groups
16:50
Ether Linkages Instead of Ester Linkages
20:05
Galactolipids
23:39
Galactolipids Overview
23:40
Monogalactosyldiacylglycerol: MGDG
25:17
Digalactosyldiacylglycerol: DGDG
28:13
Structure Examples 1: Lipid Bilayer
31:35
Structure Examples 2: Cross Section of a Cell
34:56
Structure Examples 3: MGDG & DGDG
36:28
Membrane Lipids, Part 2

38m 20s

Intro
0:00
Sphingolipids
0:11
Sphingolipid Overview
0:12
Sphingosine Structure
1:42
Ceramide
3:56
Subclasses of Sphingolipids Overview
6:00
Subclasses of Sphingolipids: Sphingomyelins
7:53
Sphingomyelins
7:54
Subclasses of Sphingolipids: Glycosphingolipid
12:47
Glycosphingolipid Overview
12:48
Cerebrosides & Globosides Overview
14:33
Example: Cerebrosides
15:43
Example: Globosides
17:14
Subclasses of Sphingolipids: Gangliosides
19:07
Gangliosides
19:08
Medical Application: Tay-Sachs Disease
23:34
Sterols
30:45
Sterols: Basic Structure
30:46
Important Example: Cholesterol
32:01
Structures Example
34:13
The Biologically Active Lipids

48m 36s

Intro
0:00
The Biologically Active Lipids
0:44
Phosphatidyl Inositol Structure
0:45
Phosphatidyl Inositol Reaction
3:24
Image Example
12:49
Eicosanoids
14:12
Arachidonic Acid & Membrane Lipid Containing Arachidonic Acid
18:41
Three Classes of Eicosanoids
20:42
Overall Structures
21:38
Prostagladins
22:56
Thromboxane
27:19
Leukotrienes
30:19
More On The Biologically Active Lipids
33:34
Steroid Hormones
33:35
Fat Soluble Vitamins
38:25
Vitamin D₃
40:40
Vitamin A
43:17
Vitamin E
45:12
Vitamin K
47:17
Section 8: Energy & Biological Systems (Bioenergetics)
Thermodynamics, Free Energy & Equilibrium

45m 51s

Intro
0:00
Thermodynamics, Free Energy and Equilibrium
1:03
Reaction: Glucose + Pi → Glucose 6-Phosphate
1:50
Thermodynamics & Spontaneous Processes
3:31
In Going From Reactants → Product, a Reaction Wants to Release Heat
6:30
A Reaction Wants to Become More Disordered
9:10
∆H < 0
10:30
∆H > 0
10:57
∆S > 0
11:23
∆S <0
11:56
∆G = ∆H - T∆S at Constant Pressure
12:15
Gibbs Free Energy
15:00
∆G < 0
16:49
∆G > 0
17:07
Reference Frame For Thermodynamics Measurements
17:57
More On BioChemistry Standard
22:36
Spontaneity
25:36
Keq
31:45
Example: Glucose + Pi → Glucose 6-Phosphate
34:14
Example Problem 1
40:25
Question
40:26
Solution
41:12
More on Thermodynamics & Free Energy

37m 6s

Intro
0:00
More on Thermodynamics & Free Energy
0:16
Calculating ∆G Under Standard Conditions
0:17
Calculating ∆G Under Physiological Conditions
2:05
∆G < 0
5:39
∆G = 0
7:03
Reaction Moving Forward Spontaneously
8:00
∆G & The Maximum Theoretical Amount of Free Energy Available
10:36
Example Problem 1
13:11
Reactions That Have Species in Common
17:48
Example Problem 2: Part 1
20:10
Example Problem 2: Part 2- Enzyme Hexokinase & Coupling
25:08
Example Problem 2: Part 3
30:34
Recap
34:45
ATP & Other High-Energy Compounds

44m 32s

Intro
0:00
ATP & Other High-Energy Compounds
0:10
Endergonic Reaction Coupled With Exergonic Reaction
0:11
Major Theme In Metabolism
6:56
Why the ∆G°' for ATP Hydrolysis is Large & Negative
12:24
∆G°' for ATP Hydrolysis
12:25
Reason 1: Electrostatic Repulsion
14:24
Reason 2: Pi & Resonance Forms
15:33
Reason 3: Concentrations of ADP & Pi
17:32
ATP & Other High-Energy Compounds Cont'd
18:48
More On ∆G°' & Hydrolysis
18:49
Other Compounds That Have Large Negative ∆G°' of Hydrolysis: Phosphoenol Pyruvate (PEP)
25:14
Enzyme Pyruvate Kinase
30:36
Another High Energy Molecule: 1,3 Biphosphoglycerate
36:17
Another High Energy Molecule: Phophocreatine
39:41
Phosphoryl Group Transfers

30m 8s

Intro
0:00
Phosphoryl Group Transfer
0:27
Phosphoryl Group Transfer Overview
0:28
Example: Glutamate → Glutamine Part 1
7:11
Example: Glutamate → Glutamine Part 2
13:29
ATP Not Only Transfers Phosphoryl, But Also Pyrophosphoryl & Adenylyl Groups
17:03
Attack At The γ Phosphorous Transfers a Phosphoryl
19:02
Attack At The β Phosphorous Gives Pyrophosphoryl
22:44
Oxidation-Reduction Reactions

49m 46s

Intro
0:00
Oxidation-Reduction Reactions
1:32
Redox Reactions
1:33
Example 1: Mg + Al³⁺ → Mg²⁺ + Al
3:49
Reduction Potential Definition
10:47
Reduction Potential Example
13:38
Organic Example
22:23
Review: How To Find The Oxidation States For Carbon
24:15
Examples: Oxidation States For Carbon
27:45
Example 1: Oxidation States For Carbon
27:46
Example 2: Oxidation States For Carbon
28:36
Example 3: Oxidation States For Carbon
29:18
Example 4: Oxidation States For Carbon
29:44
Example 5: Oxidation States For Carbon
30:10
Example 6: Oxidation States For Carbon
30:40
Example 7: Oxidation States For Carbon
31:20
Example 8: Oxidation States For Carbon
32:10
Example 9: Oxidation States For Carbon
32:52
Oxidation-Reduction Reactions, cont'd
35:22
More On Reduction Potential
35:28
Lets' Start With ∆G = ∆G°' + RTlnQ
38:29
Example: Oxidation Reduction Reactions
41:42
More On Oxidation-Reduction Reactions

56m 34s

Intro
0:00
More On Oxidation-Reduction Reactions
0:10
Example 1: What If the Concentrations Are Not Standard?
0:11
Alternate Procedure That Uses The 1/2 Reactions Individually
8:57
Universal Electron Carriers in Aqueous Medium: NAD+ & NADH
15:12
The Others Are…
19:22
NAD+ & NADP Coenzymes
20:56
FMN & FAD
22:03
Nicotinamide Adenine Dinucleotide (Phosphate)
23:03
Reduction 1/2 Reactions
36:10
Ratio of NAD+ : NADH
36:52
Ratio of NADPH : NADP+
38:02
Specialized Roles of NAD+ & NADPH
38:48
Oxidoreductase Enzyme Overview
40:26
Examples of Oxidoreductase
43:32
The Flavin Nucleotides
46:46
Example Problems For Bioenergetics

42m 12s

Intro
0:00
Example 1: Calculate the ∆G°' For The Following Reaction
1:04
Example 1: Question
1:05
Example 1: Solution
2:20
Example 2: Calculate the Keq For the Following
4:20
Example 2: Question
4:21
Example 2: Solution
5:54
Example 3: Calculate the ∆G°' For The Hydrolysis of ATP At 25°C
8:52
Example 3: Question
8:53
Example 3: Solution
10:30
Example 3: Alternate Procedure
13:48
Example 4: Problems For Bioenergetics
16:46
Example 4: Questions
16:47
Example 4: Part A Solution
21:19
Example 4: Part B Solution
23:26
Example 4: Part C Solution
26:12
Example 5: Problems For Bioenergetics
29:27
Example 5: Questions
29:35
Example 5: Solution - Part 1
32:16
Example 5: Solution - Part 2
34:39
Section 9: Glycolysis and Gluconeogenesis
Overview of Glycolysis I

43m 32s

Intro
0:00
Overview of Glycolysis
0:48
Three Primary Paths For Glucose
1:04
Preparatory Phase of Glycolysis
4:40
Payoff Phase of Glycolysis
6:40
Glycolysis Reactions Diagram
7:58
Enzymes of Glycolysis
12:41
Glycolysis Reactions
16:02
Step 1
16:03
Step 2
18:03
Step 3
18:52
Step 4
20:08
Step 5
21:42
Step 6
22:44
Step 7
24:22
Step 8
25:11
Step 9
26:00
Step 10
26:51
Overview of Glycolysis Cont.
27:28
The Overall Reaction for Glycolysis
27:29
Recall The High-Energy Phosphorylated Compounds Discusses In The Bioenergetics Unit
33:10
What Happens To The Pyruvate That Is Formed?
37:58
Glycolysis II

1h 1m 47s

Intro
0:00
Glycolysis Step 1: The Phosphorylation of Glucose
0:27
Glycolysis Step 1: Reaction
0:28
Hexokinase
2:28
Glycolysis Step 1: Mechanism-Simple Nucleophilic Substitution
6:34
Glycolysis Step 2: Conversion of Glucose 6-Phosphate → Fructose 6-Phosphate
11:33
Glycolysis Step 2: Reaction
11:34
Glycolysis Step 2: Mechanism, Part 1
14:40
Glycolysis Step 2: Mechanism, Part 2
18:16
Glycolysis Step 2: Mechanism, Part 3
19:56
Glycolysis Step 2: Mechanism, Part 4 (Ring Closing & Dissociation)
21:54
Glycolysis Step 3: Conversion of Fructose 6-Phosphate to Fructose 1,6-Biphosphate
24:16
Glycolysis Step 3: Reaction
24:17
Glycolysis Step 3: Mechanism
26:40
Glycolysis Step 4: Cleavage of Fructose 1,6-Biphosphate
31:10
Glycolysis Step 4: Reaction
31:11
Glycolysis Step 4: Mechanism, Part 1 (Binding & Ring Opening)
35:26
Glycolysis Step 4: Mechanism, Part 2
37:40
Glycolysis Step 4: Mechanism, Part 3
39:30
Glycolysis Step 4: Mechanism, Part 4
44:00
Glycolysis Step 4: Mechanism, Part 5
46:34
Glycolysis Step 4: Mechanism, Part 6
49:00
Glycolysis Step 4: Mechanism, Part 7
50:12
Hydrolysis of The Imine
52:33
Glycolysis Step 5: Conversion of Dihydroxyaceton Phosphate to Glyceraldehyde 3-Phosphate
55:38
Glycolysis Step 5: Reaction
55:39
Breakdown and Numbering of Sugar
57:40
Glycolysis III

59m 17s

Intro
0:00
Glycolysis Step 5: Conversion of Dihydroxyaceton Phosphate to Glyceraldehyde 3-Phosphate
0:44
Glycolysis Step 5: Mechanism, Part 1
0:45
Glycolysis Step 5: Mechanism, Part 2
3:53
Glycolysis Step 6: Oxidation of Glyceraldehyde 3-Phosphate to 1,3-Biphosphoglycerate
5:14
Glycolysis Step 6: Reaction
5:15
Glycolysis Step 6: Mechanism, Part 1
8:52
Glycolysis Step 6: Mechanism, Part 2
12:58
Glycolysis Step 6: Mechanism, Part 3
14:26
Glycolysis Step 6: Mechanism, Part 4
16:23
Glycolysis Step 7: Phosphoryl Transfer From 1,3-Biphosphoglycerate to ADP to Form ATP
19:08
Glycolysis Step 7: Reaction
19:09
Substrate-Level Phosphorylation
23:18
Glycolysis Step 7: Mechanism (Nucleophilic Substitution)
26:57
Glycolysis Step 8: Conversion of 3-Phosphoglycerate to 2-Phosphoglycerate
28:44
Glycolysis Step 8: Reaction
28:45
Glycolysis Step 8: Mechanism, Part 1
30:08
Glycolysis Step 8: Mechanism, Part 2
32:24
Glycolysis Step 8: Mechanism, Part 3
34:02
Catalytic Cycle
35:42
Glycolysis Step 9: Dehydration of 2-Phosphoglycerate to Phosphoenol Pyruvate
37:20
Glycolysis Step 9: Reaction
37:21
Glycolysis Step 9: Mechanism, Part 1
40:12
Glycolysis Step 9: Mechanism, Part 2
42:01
Glycolysis Step 9: Mechanism, Part 3
43:58
Glycolysis Step 10: Transfer of a Phosphoryl Group From Phosphoenol Pyruvate To ADP To Form ATP
45:16
Glycolysis Step 10: Reaction
45:17
Substrate-Level Phosphorylation
48:32
Energy Coupling Reaction
51:24
Glycolysis Balance Sheet
54:15
Glycolysis Balance Sheet
54:16
What Happens to The 6 Carbons of Glucose?
56:22
What Happens to 2 ADP & 2 Pi?
57:04
What Happens to The 4e⁻ ?
57:15
Glycolysis IV

39m 47s

Intro
0:00
Feeder Pathways
0:42
Feeder Pathways Overview
0:43
Starch, Glycogen
2:25
Lactose
4:38
Galactose
4:58
Manose
5:22
Trehalose
5:45
Sucrose
5:56
Fructose
6:07
Fates of Pyruvate: Aerobic & Anaerobic Conditions
7:39
Aerobic Conditions & Pyruvate
7:40
Anaerobic Fates of Pyruvate
11:18
Fates of Pyruvate: Lactate Acid Fermentation
14:10
Lactate Acid Fermentation
14:11
Fates of Pyruvate: Ethanol Fermentation
19:01
Ethanol Fermentation Reaction
19:02
TPP: Thiamine Pyrophosphate (Functions and Structure)
23:10
Ethanol Fermentation Mechanism, Part 1
27:53
Ethanol Fermentation Mechanism, Part 2
29:06
Ethanol Fermentation Mechanism, Part 3
31:15
Ethanol Fermentation Mechanism, Part 4
32:44
Ethanol Fermentation Mechanism, Part 5
34:33
Ethanol Fermentation Mechanism, Part 6
35:48
Gluconeogenesis I

41m 34s

Intro
0:00
Gluconeogenesis, Part 1
1:02
Gluconeogenesis Overview
1:03
3 Glycolytic Reactions That Are Irreversible Under Physiological Conditions
2:29
Gluconeogenesis Reactions Overview
6:17
Reaction: Pyruvate to Oxaloacetate
11:07
Reaction: Oxaloacetate to Phosphoenolpyruvate (PEP)
13:29
First Pathway That Pyruvate Can Take to Become Phosphoenolpyruvate
15:24
Second Pathway That Pyruvate Can Take to Become Phosphoenolpyruvate
21:00
Transportation of Pyruvate From The Cytosol to The Mitochondria
24:15
Transportation Mechanism, Part 1
26:41
Transportation Mechanism, Part 2
30:43
Transportation Mechanism, Part 3
34:04
Transportation Mechanism, Part 4
38:14
Gluconeogenesis II

34m 18s

Intro
0:00
Oxaloacetate → Phosphoenolpyruvate (PEP)
0:35
Mitochondrial Membrane Does Not Have a Transporter for Oxaloactate
0:36
Reaction: Oxaloacetate to Phosphoenolpyruvate (PEP)
3:36
Mechanism: Oxaloacetate to Phosphoenolpyruvate (PEP)
4:48
Overall Reaction: Pyruvate to Phosphoenolpyruvate
7:01
Recall The Two Pathways That Pyruvate Can Take to Become Phosphoenolpyruvate
10:16
NADH in Gluconeogenesis
12:29
Second Pathway: Lactate → Pyruvate
18:22
Cytosolic PEP Carboxykinase, Mitochondrial PEP Carboxykinase, & Isozymes
18:23
2nd Bypass Reaction
23:04
3rd Bypass Reaction
24:01
Overall Process
25:17
Other Feeder Pathways For Gluconeogenesis
26:35
Carbon Intermediates of The Citric Acid Cycle
26:36
Amino Acids & The Gluconeogenic Pathway
29:45
Glycolysis & Gluconeogenesis Are Reciprocally Regulated
32:00
The Pentose Phosphate Pathway

42m 52s

Intro
0:00
The Pentose Phosphate Pathway Overview
0:17
The Major Fate of Glucose-6-Phosphate
0:18
The Pentose Phosphate Pathway (PPP) Overview
1:00
Oxidative Phase of The Pentose Phosphate Pathway
4:33
Oxidative Phase of The Pentose Phosphate Pathway: Reaction Overview
4:34
Ribose-5-Phosphate: Glutathione & Reductive Biosynthesis
9:02
Glucose-6-Phosphate to 6-Phosphogluconate
12:48
6-Phosphogluconate to Ribulose-5-Phosphate
15:39
Ribulose-5-Phosphate to Ribose-5-Phosphate
17:05
Non-Oxidative Phase of The Pentose Phosphate Pathway
19:55
Non-Oxidative Phase of The Pentose Phosphate Pathway: Overview
19:56
General Transketolase Reaction
29:03
Transaldolase Reaction
35:10
Final Transketolase Reaction
39:10
Section 10: The Citric Acid Cycle (Krebs Cycle)
Citric Acid Cycle I

36m 10s

Intro
0:00
Stages of Cellular Respiration
0:23
Stages of Cellular Respiration
0:24
From Pyruvate to Acetyl-CoA
6:56
From Pyruvate to Acetyl-CoA: Pyruvate Dehydrogenase Complex
6:57
Overall Reaction
8:42
Oxidative Decarboxylation
11:54
Pyruvate Dehydrogenase (PDH) & Enzymes
15:30
Pyruvate Dehydrogenase (PDH) Requires 5 Coenzymes
17:15
Molecule of CoEnzyme A
18:52
Thioesters
20:56
Lipoic Acid
22:31
Lipoate Is Attached To a Lysine Residue On E₂
24:42
Pyruvate Dehydrogenase Complex: Reactions
26:36
E1: Reaction 1 & 2
30:38
E2: Reaction 3
31:58
E3: Reaction 4 & 5
32:44
Substrate Channeling
34:17
Citric Acid Cycle II

49m 20s

Intro
0:00
Citric Acid Cycle Reactions Overview
0:26
Citric Acid Cycle Reactions Overview: Part 1
0:27
Citric Acid Cycle Reactions Overview: Part 2
7:03
Things to Note
10:58
Citric Acid Cycle Reactions & Mechanism
13:57
Reaction 1: Formation of Citrate
13:58
Reaction 1: Mechanism
19:01
Reaction 2: Citrate to Cis Aconistate to Isocitrate
28:50
Reaction 3: Isocitrate to α-Ketoglutarate
32:35
Reaction 3: Two Isocitrate Dehydrogenase Enzymes
36:24
Reaction 3: Mechanism
37:33
Reaction 4: Oxidation of α-Ketoglutarate to Succinyl-CoA
41:38
Reaction 4: Notes
46:34
Citric Acid Cycle III

44m 11s

Intro
0:00
Citric Acid Cycle Reactions & Mechanism
0:21
Reaction 5: Succinyl-CoA to Succinate
0:24
Reaction 5: Reaction Sequence
2:35
Reaction 6: Oxidation of Succinate to Fumarate
8:28
Reaction 7: Fumarate to Malate
10:17
Reaction 8: Oxidation of L-Malate to Oxaloacetate
14:15
More On The Citric Acid Cycle
17:17
Energy from Oxidation
17:18
How Can We Transfer This NADH Into the Mitochondria
27:10
Citric Cycle is Amphibolic - Works In Both Anabolic & Catabolic Pathways
32:06
Biosynthetic Processes
34:29
Anaplerotic Reactions Overview
37:26
Anaplerotic: Reaction 1
41:42
Section 11: Catabolism of Fatty Acids
Fatty Acid Catabolism I

48m 11s

Intro
0:00
Introduction to Fatty Acid Catabolism
0:21
Introduction to Fatty Acid Catabolism
0:22
Vertebrate Cells Obtain Fatty Acids for Catabolism From 3 Sources
2:16
Diet: Part 1
4:00
Diet: Part 2
5:35
Diet: Part 3
6:20
Diet: Part 4
6:47
Diet: Part 5
10:18
Diet: Part 6
10:54
Diet: Part 7
12:04
Diet: Part 8
12:26
Fats Stored in Adipocytes Overview
13:54
Fats Stored in Adipocytes (Fat Cells): Part 1
16:13
Fats Stored in Adipocytes (Fat Cells): Part 2
17:16
Fats Stored in Adipocytes (Fat Cells): Part 3
19:42
Fats Stored in Adipocytes (Fat Cells): Part 4
20:52
Fats Stored in Adipocytes (Fat Cells): Part 5
22:56
Mobilization of TAGs Stored in Fat Cells
24:35
Fatty Acid Oxidation
28:29
Fatty Acid Oxidation
28:48
3 Reactions of the Carnitine Shuttle
30:42
Carnitine Shuttle & The Mitochondrial Matrix
36:25
CAT I
43:58
Carnitine Shuttle is the Rate-Limiting Steps
46:24
Fatty Acid Catabolism II

45m 58s

Intro
0:00
Fatty Acid Catabolism
0:15
Fatty Acid Oxidation Takes Place in 3 Stages
0:16
β-Oxidation
2:05
β-Oxidation Overview
2:06
Reaction 1
4:20
Reaction 2
7:35
Reaction 3
8:52
Reaction 4
10:16
β-Oxidation Reactions Discussion
11:34
Notes On β-Oxidation
15:14
Double Bond After The First Reaction
15:15
Reaction 1 is Catalyzed by 3 Isozymes of Acyl-CoA Dehydrogenase
16:04
Reaction 2 & The Addition of H₂O
18:38
After Reaction 4
19:24
Production of ATP
20:04
β-Oxidation of Unsaturated Fatty Acid
21:25
β-Oxidation of Unsaturated Fatty Acid
22:36
β-Oxidation of Mono-Unsaturates
24:49
β-Oxidation of Mono-Unsaturates: Reaction 1
24:50
β-Oxidation of Mono-Unsaturates: Reaction 2
28:43
β-Oxidation of Mono-Unsaturates: Reaction 3
30:50
β-Oxidation of Mono-Unsaturates: Reaction 4
31:06
β-Oxidation of Polyunsaturates
32:29
β-Oxidation of Polyunsaturates: Part 1
32:30
β-Oxidation of Polyunsaturates: Part 2
37:08
β-Oxidation of Polyunsaturates: Part 3
40:25
Fatty Acid Catabolism III

33m 18s

Intro
0:00
Fatty Acid Catabolism
0:43
Oxidation of Fatty Acids With an Odd Number of Carbons
0:44
β-oxidation in the Mitochondrion & Two Other Pathways
9:08
ω-oxidation
10:37
α-oxidation
17:22
Ketone Bodies
19:08
Two Fates of Acetyl-CoA Formed by β-Oxidation Overview
19:09
Ketone Bodies: Acetone
20:42
Ketone Bodies: Acetoacetate
20:57
Ketone Bodies: D-β-hydroxybutyrate
21:25
Two Fates of Acetyl-CoA Formed by β-Oxidation: Part 1
22:05
Two Fates of Acetyl-CoA Formed by β-Oxidation: Part 2
26:59
Two Fates of Acetyl-CoA Formed by β-Oxidation: Part 3
30:52
Section 12: Catabolism of Amino Acids and the Urea Cycle
Overview & The Aminotransferase Reaction

40m 59s

Intro
0:00
Overview of The Aminotransferase Reaction
0:25
Overview of The Aminotransferase Reaction
0:26
The Aminotransferase Reaction: Process 1
3:06
The Aminotransferase Reaction: Process 2
6:46
Alanine From Muscle Tissue
10:54
Bigger Picture of the Aminotransferase Reaction
14:52
Looking Closely at Process 1
19:04
Pyridoxal Phosphate (PLP)
24:32
Pyridoxamine Phosphate
25:29
Pyridoxine (B6)
26:38
The Function of PLP
27:12
Mechanism Examples
28:46
Reverse Reaction: Glutamate to α-Ketoglutarate
35:34
Glutamine & Alanine: The Urea Cycle I

39m 18s

Intro
0:00
Glutamine & Alanine: The Urea Cycle I
0:45
Excess Ammonia, Glutamate, and Glutamine
0:46
Glucose-Alanine Cycle
9:54
Introduction to the Urea Cycle
20:56
The Urea Cycle: Production of the Carbamoyl Phosphate
22:59
The Urea Cycle: Reaction & Mechanism Involving the Carbamoyl Phosphate Synthetase
33:36
Glutamine & Alanine: The Urea Cycle II

36m 21s

Intro
0:00
Glutamine & Alanine: The Urea Cycle II
0:14
The Urea Cycle Overview
0:34
Reaction 1: Ornithine → Citrulline
7:30
Reaction 2: Citrulline → Citrullyl-AMP
11:15
Reaction 2': Citrullyl-AMP → Argininosuccinate
15:25
Reaction 3: Argininosuccinate → Arginine
20:42
Reaction 4: Arginine → Orthinine
24:00
Links Between the Citric Acid Cycle & the Urea Cycle
27:47
Aspartate-argininosuccinate Shunt
32:36
Amino Acid Catabolism

47m 58s

Intro
0:00
Amino Acid Catabolism
0:10
Common Amino Acids and 6 Major Products
0:11
Ketogenic Amino Acid
1:52
Glucogenic Amino Acid
2:51
Amino Acid Catabolism Diagram
4:18
Cofactors That Play a Role in Amino Acid Catabolism
7:00
Biotin
8:42
Tetrahydrofolate
10:44
S-Adenosylmethionine (AdoMet)
12:46
Tetrahydrobiopterin
13:53
S-Adenosylmethionine & Tetrahydrobiopterin Molecules
14:41
Catabolism of Phenylalanine
18:30
Reaction 1: Phenylalanine to Tyrosine
18:31
Reaction 2: Tyrosine to p-Hydroxyphenylpyruvate
21:36
Reaction 3: p-Hydroxyphenylpyruvate to Homogentisate
23:50
Reaction 4: Homogentisate to Maleylacetoacetate
25:42
Reaction 5: Maleylacetoacetate to Fumarylacetoacetate
28:20
Reaction 6: Fumarylacetoacetate to Fumarate & Succinyl-CoA
29:51
Reaction 7: Fate of Fumarate & Succinyl-CoA
31:14
Phenylalanine Hydroxylase
33:33
The Phenylalanine Hydroxylase Reaction
33:34
Mixed-Function Oxidases
40:26
When Phenylalanine Hydoxylase is Defective: Phenylketonuria (PKU)
44:13
Section 13: Oxidative Phosphorylation and ATP Synthesis
Oxidative Phosphorylation I

41m 11s

Intro
0:00
Oxidative Phosphorylation
0:54
Oxidative Phosphorylation Overview
0:55
Mitochondrial Electron Transport Chain Diagram
7:15
Enzyme Complex I of the Electron Transport Chain
12:27
Enzyme Complex II of the Electron Transport Chain
14:02
Enzyme Complex III of the Electron Transport Chain
14:34
Enzyme Complex IV of the Electron Transport Chain
15:30
Complexes Diagram
16:25
Complex I
18:25
Complex I Overview
18:26
What is Ubiquinone or Coenzyme Q?
20:02
Coenzyme Q Transformation
22:37
Complex I Diagram
24:47
Fe-S Proteins
26:42
Transfer of H⁺
29:42
Complex II
31:06
Succinate Dehydrogenase
31:07
Complex II Diagram & Process
32:54
Other Substrates Pass Their e⁻ to Q: Glycerol 3-Phosphate
37:31
Other Substrates Pass Their e⁻ to Q: Fatty Acyl-CoA
39:02
Oxidative Phosphorylation II

36m 27s

Intro
0:00
Complex III
0:19
Complex III Overview
0:20
Complex III: Step 1
1:56
Complex III: Step 2
6:14
Complex IV
8:42
Complex IV: Cytochrome Oxidase
8:43
Oxidative Phosphorylation, cont'd
17:18
Oxidative Phosphorylation: Summary
17:19
Equation 1
19:13
How Exergonic is the Reaction?
21:03
Potential Energy Represented by Transported H⁺
27:24
Free Energy Change for the Production of an Electrochemical Gradient Via an Ion Pump
28:48
Free Energy Change in Active Mitochondria
32:02
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Lecture Comments (7)

1 answer

Last reply by: Professor Hovasapian
Thu Aug 23, 2018 8:15 AM

Post by Swati Sharma on August 21, 2018

Dear Dr Raffi, I am a little confused and so I have understood the following so far :
Oxidative Phase
So now G6P instead of getting converted to F6P rather gets converted to Ribulose 5 phosphate which gets isomerized  to Ribose 5 Phosphate for the biosynthesis of nucleotides.

For Non oxidative Phase,

cells that do not require Ribose 5 Phosphate have to get converted back to G6P for the continuation of the oxidative phase for the regeneration of NADPH. So here I am getting confused does this mean that the Non Oxidative Phase is required for the continuation of Oxidative phase unless and until cells demand Ribose 5 Phosphate?. So in summary the process of entire conversion of G6P to Ribose 5 Phosphate is the OXIDATIVE PHASE, BUT the conversion of Ribulose 5 phosphate to F6P and then back to G6P is the NONOXIDATIVE PHASE and from there  the production of NADPH keeps happening for the anabolic processes and that is the OXIDATIVE PHASE? So all the way from G6P to RIBOSE 5 POSPHATE IS THE OXIDATIVE PHASE, AND RECONVERSION OF RIBOSE 5 POSPHATE BACK TO G6P IS THE NON OXIDATIVE PHASE IF RIBOSE 5 POSPHATE NOT REQUIRED? Please let me know if I am correct.

Very Respectfully
Swati

1 answer

Last reply by: Professor Hovasapian
Fri Oct 24, 2014 10:02 PM

Post by Tim Zhang on October 22, 2014

Your lectures helped me a lot. However I faced a really difficult question on this topic, could you help me solve this?  
The question ask that average human requires about 2,000 kcal of energy per day, which is equivalent to about 3 mol of glucose per day. It is a lot calories! but why don't humans spontaneously combust?

2 answers

Last reply by: tiffany yang
Wed Nov 13, 2013 10:07 PM

Post by tiffany yang on November 13, 2013

Dear professor,
I have an exam this friday, but I'm confused on the transaldolase reaction....isn't ketose being transferred as well? just like all the other nonoxidative reactions? so why is that one called transaldolase reaction, instead of transketolase rxn? Thanks! Your so amazing!

ALso, I read from my teacher's study material that there are four modes for PPP, depending on the needs , in mode one, where cell only needs ribose, then there WILL be nonoxidative reaction, so that fructose 6 phosphate and glyceral 3-phosphate will use the non oxidative PPP pathway to go back to ribose.(because we need ribose) THis I understand;

however, I don't understand why, when both ribose and NAPDG are needed, then there won't be non oxidative reaction happening. (the reason one the study guide was that because the product ribose is needed, therefore we don't want the non oxidative part to recycle those ribose, because we need those ribose.)

seems like these two are contradicting. Thanks.

Related Articles:

The Pentose Phosphate Pathway

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  • Intro 0:00
  • The Pentose Phosphate Pathway Overview 0:17
    • The Major Fate of Glucose-6-Phosphate
    • The Pentose Phosphate Pathway (PPP) Overview
  • Oxidative Phase of The Pentose Phosphate Pathway 4:33
    • Oxidative Phase of The Pentose Phosphate Pathway: Reaction Overview
    • Ribose-5-Phosphate: Glutathione & Reductive Biosynthesis
    • Glucose-6-Phosphate to 6-Phosphogluconate
    • 6-Phosphogluconate to Ribulose-5-Phosphate
    • Ribulose-5-Phosphate to Ribose-5-Phosphate
  • Non-Oxidative Phase of The Pentose Phosphate Pathway 19:55
    • Non-Oxidative Phase of The Pentose Phosphate Pathway: Overview
    • General Transketolase Reaction
    • Transaldolase Reaction
    • Final Transketolase Reaction

Transcription: The Pentose Phosphate Pathway

Hello and welcome back to Educator.com, and welcome back to Biochemistry.0000

We have been discussing glycolysis and gluconeogenesis, and we are going to close out our discussion of this unit by discussing the pentose phosphate pathway, so let's go ahead and jump right on in.0004

OK, we know that the major fate of glucose 6-phosphate, actually, is glycolysis.0018

The major fate of our glucose 6-phosphate is glycolysis, and we spent a large amount of time discussing that.0029

Quick recap: glycolysis- we formed pyruvate; pyruvate becomes acetyl-CoA.0043

Acetyl-CoA enters the citric acid cycle, and it goes on to the electron transport chain and oxidative phosphorylation- all of which, we will be discussing, not a problem.0049

However, another important fate of glucose 6-phosphate is the pentose phosphate pathway.0061

Another pathway for the glucose 6-phosphate is the - I will just call it PPP - the pentose phosphate pathway.0070

OK, this is the formation of pentose phosphates - 5 carbons sugars - that are ultimately used by the cell to form things like RNAs and DNA and ATP, NADH, FADH2 - things like that, I will also put - and coenzyme A.0082

That is another fate for the glucose 6-phosphate; instead of glycolysis, it can actually take another pathway.0129

Now, in this pathway - in PPP - NADP+ is the electron acceptor.0135

We saw in glycolysis that it was the NAD+ that ended up oxidizing and accepting the electrons.0145

Here, it is NADP+; it is still doing the same thing.0152

It is just oxidizing; it is taking a couple of electrons away, taking a couple of hydrogens away - that is it - and then, ultimately giving them over to the electron transport chain.0156

It is the electron acceptor, the oxidizer, and the NADPH that is formed upon oxidization of these biomolecules is needed, used in anabolic pathways - in other words, biosynthesis - and anti-oxygen radical chemistry.0166

It basically acts as...it participates in anti-oxidant chemistry.0216

OK, now, the pentose phosphate pathway has an oxidative phase and a non-oxidative phase.0223

OK, let's go ahead and diagram this out, so that we will have a look at it; and then, we will go ahead and take a look at the individual reactions of the pathway.0247

It is a rather short pathway; it is not a problem.0256

There is only 1 part of it - the non-oxidative - that looks like it is a little involved, at least it will on the page, but again, it really only consists of 3 reactions.0258

Let me see; do I want to do it here?0268

No, you know what, I think I will start on the next page.0270

Let me go ahead and put that there, and I think I am going to go ahead and do this in...I think I will do this in blue, why not?0274

Just for a change of pace, OK, let's go ahead and write oxidative up here.0281

Yes, I will write oxidative phase up here, and then, I will write the non-oxidative over here; and hopefully, we can work this out.0288

We have got our glucose 6-phosphate.0300

I will go ahead and write everything out, and in a couple of steps, we are going to end up forming our 6-phosphoglucanate.0306

Again, it is going to be up to your teacher whether he or she wants you to actually memorize this or just know that it exists.0324

Whether you actually have to know what is formed, be able to reproduce it or be able to, at least, passively identify it, label it, know the enzymes, it is going to be up to them, but we will have discussed it.0330

6-phosphoglucanate to ribulose, I will go ahead and write everything out, and then, I will go back and fill in all of the enzymes and all of the cofactors, ribulose 5-phosphate, and finally, we have ribose 5-phosphate.0340

OK, in this phase right here, we have NADP.0367

I always forget the P; I am so used to NAD all the time.0376

So, if it happens like that, please forgive me, and again, I am hoping that you will confirm all of this with the illustrations that are in your book to make sure that I have not forgotten anything.0380

There is so much information in just a simple pathway like this that it is very, very easy to forget things.0388

NADP+ comes in; we have NADPH comes out, and then, I will go ahead and do that.0393

I will go ahead and do this; I will explain what the GSH and the GSSG is in just a second and we will be talking about later, and let me see.0403

6-phosphoglucanate to ribulose 5-phosphate, CO2 actually ends up coming out there.0414

And then, again, another oxidation takes place because it is the oxidative phase.0420

NADP+ and NADPH comes out, and here, we will go ahead and do this; and we will just call this reductive biosynthesis anabolic pathways- that is it.0425

You know what, let me rewrite this oxidative just a little...in fact, I am going to go ahead and do this in red.0451

This is the oxidative phase, and the non-oxidative - here, we will just diagram it out - phase.0468

Now, let me go back to blue.0475

OK, we are going to have the ribulose come here like that.0479

This is going to recycle our glucose 6-phosphate, the non-oxidative phase.0485

It is not going to go on to from the ribose 5-phosphate, which gets siphoned off and goes on for use in RNA, DNA and things like that; but it recycles this, so that it can keep producing this NADPH, so that it can keep doing whatever it is supposed to be doing - reducing the glutathione - so that it can be involved in antioxidant chemistry or keep producing NADPH, so that biosynthesis can actually keep taking place.0490

OK, that is a general scheme; glucose 6-phosphate is converted to 6-phosphoglucanate in 2 steps, and then, 6-phosphoglucanate, it loses its CO2 molecule, becomes ribulose 5-phosphate, and ribulose 5- phosphate is isomerized to ribose 5-phosphate.0512

In the non-oxidative phase, if the cell does not happen to need any ribose 5-phosphate, it will come to here, and the ribulose and the ribose 5-phosphate will recycle to glucose 6-phosphate and keep going like that.0529

OK, now, let me go ahead and go to red here.0543

In the oxidative phase, the products are ribose 5-phosphate, NADPH and CO2.0549

We have our NADPH; we have our NADPH.0574

We have our CO2, and we have our ribose 5-phosphate.0577

Those are our major products of this pathway.0580

And again, the NADPH is used to reduce glutathione, which protects the cells against damage by hydrogen peroxide and the hydroxyl radical- very powerfully reactive species, very damaging.0585

A radical, if you remember, is a species with an odd number of electron.0634

There is one electron there that is very, very reactive.0638

It also is used - in other words, the NADPH - to support reductive biosynthesis.0643

OK, the ribose 5-phosphate is used...well, we know that already.0665

We have mentioned that; the ribose 5-phosphate is used as a precursor for use in the formation of other molecules, the coenzyme A, RNA, DNA- things like that.0676

OK, now, for cells that do not require the ribose 5-phosphate - the non-oxidative phase, the non-ox phase - recycles the pentose back to the glucose 6-phosphate.0688

That is this pathway right here, and it does it for the continued production of the NADPH - back and forth, back and forth, back and forth, that is it.0725

This is the pentose phosphate pathway; it will either go and form the ribose 5-phosphate, and then, the process goes and produces some NADPH to be used, and if the cell does not need it, it just continues the cycle like this, so that it produces NADPH for whatever it is that the cell needs.0752

OK, now, let's go ahead and take a look at the individual reactions of the oxidative phase.0767

I think I am going to go back to black for this one.0776

Let's look at glucose 6-phosphate here, 1, 2, here, here, here, here.0780

Let's go ahead and do this, bottom, top, bottom, C, O, and I have got PO32-.0787

The first step, I will go ahead and do that.0798

Let me get a little bit bigger; what the heck.0803

I have got that; I said we have got NADP+ coming in.0808

We have got NADPH coming out.0815

The enzyme for this is glucose 6-phosphate dehydrogenase, and it also requires magnesium 2+, most dehydrogenases do.0821

OK, now, this particular reaction, what it does is the following.0837

Yes, it is fine; OK, it actually ends up forming...that is that.0844

That is that; yes, I remembered it there.0854

OK, C, O, PO32-, we end up forming this thing called...actually, I will put the names in a minute.0857

And then, from here, let's go ahead and come down here.0869

OK, from here, an enzyme called - well, I will put the enzymes...lay out...let me put it here - lactonase.0874

This is a lactone; It is an ester, which is involved in a ring.0883

OK, 6-phosphoglucono-delta-lactone, I will write the names in just a minute.0888

It is just an ester, C, double bond O, C; it just happens to be in a ring.0892

That is what a lactone means; OK, now, this lactonase, actually, opens up the ring, and what you end up with is the following.0897

You end up with the...yes, let me put it...yes, it is fine, 1, 2, 3, 4, 5.0905

Let me make sure I have enough room here; I will go ahead and put the carbonyl up here.0913

It is that, and then, we have OH; and we have H.0920

We have H over here; we have OH over here, and then, we have our OH, our OH, and then, of course, we have our PO32-.0925

So, we actually open this up; now, the other reaction is going to be this one.0937

We are going to have NADP+ come in, NADPH come out, and this is also where CO2 comes out.0944

You know what, I am actually going to...sorry about that; I am going to put the CO2 on top, so that I can write the enzyme name underneath.0959

CO2 also leaves, and the enzyme here is 6-phosphoglucanate dehydrogenase.0965

OK, and what we end up forming is the following; the CO2, that is this CO2 right here that goes away.0984

The dehydrogenase part, what it, actually, ends up doing, it, actually, takes this hydrogen away, and it takes this hydrogen away to form a double bond at this carbon.0991

What you end up with is the following 5-carbon fragment.1002

I will go ahead and stay here, 1, 2, 3, 4, 5.1007

What you end up with is OH, H; what you end up with is a carbonyl.1012

You end up with OH; you end up with OH, and you end up with our PO32-.1018

This is the ribulose 5-phosphate; now, what happens here is this enzyme, pentose phosphate isomerase or isomerase, and what it does is it flips this and this.1023

The carbonyl, it turns this from a ketose into an aldose.1044

We have C, C, C, C, C, and now, the carbonyl ends up up here with an H; and the alcohol ends up here.1049

This is the ribose 5-phosphate, and I will go ahead and put a circle around the P for PO32-.1064

Now, let me go ahead and write the names in; I will go ahead and write this in blue.1070

This is our glucose 6-phosphate.1074

OK, this is 6-phosphogluco-delta-lactone.1078

Well, delta gluco, glucono, I do not know.1089

Glucono-delta-lactone, it does not really matter- gluco, glucono.1096

OK, this right here, this is 6-phosphoglucanate.1101

This is 6-phosphoglucanate.1108

That is that molecule right there; OK, this is ribulose 5-phosphate, and this is the ribose 5-phosphate.1116

You remember the names; the ketose has the U-L: ribulose-ribose, xylulose-xylose- things like that.1128

This is the ketose, ketone; this is the aldehyde version.1138

This is the oxidative phase; from here to the lactone to the phosphogluconate, it opens it up, and then, it decarboxylates.1142

This takes the CO2 off; it oxidizes, right?1151

It takes away couple of hydrogens, converts it to a carbonyl, and then, it flips the carbonyl and the alcohol, so it looks like that.1156

This is the oxidative phase; alright, let me see.1164

Is there anything else that I need to write here?1168

I have got the enzyme names; I have got the NADP, the NADPH.1172

I have the CO2, so again, CO2 is lost; that is this CO2.1175

OK, actually I should probably put this as +H+ because this is the H1180

This is the H; that is those 2 Hs right there.1184

In any oxidation with the NAD or NADP, you end up with NADH + H+, NADPH + H+.1188

OK, OK, now, let's go ahead and take a look...this is the oxidative phase.1196

Now, we will go ahead and take a look at the non-oxidative phase.1203

OK, it is going to look like there is a lot on this page, but it is not a problem.1207

We will just draw it all out, and we will see what we have got.1212

I think I am going to go back to black for this one; I hope you do not mind.1217

Hopefully, there is enough room; I think I have got enough room to actually do this.1221

I am going to start up here, so ribose 5-phosphate, and it is going to go there, sedohep 7-phosphate; and then, we have fructose 6-phosphate.1225

OK, we have xylulose 5-phosphate, and we have glyceraldehyde-3-phosphate; and that will form our erythrose 4-phosophate.1251

Let me see; that goes that way, and this goes this way.1270

And again, I hope to God that I have enough room here.1277

Fructose 6-phosphate and I have glyceraldehyde-3-phosphate.1282

I have xylulose 5-phosphate.1291

Now, let's go ahead and see if we cannot...we are going to have a mirror image of this.1295

I think I am going to have to make this a little bit smaller.1300

I have got xylulose 5-phosphate, and a glyceraldehyde-3-phosphate.1304

Geez, I hope I have enough room to do this, fructose 6-phosphate.1315

I have erythrose 4-phosphate that comes from this.1320

Yes, I should have enough room; it should not be a problem.1330

I have glyceraldahyde-3-phosphate, and I have got sedohep 7-phosphate; then I have something coming this way and this way, and I have got, again, a xylulose 5-phophate, and I have got ribose 5-phosphate.1334

There is a mirror right here - OK - right down the middle, and, oh, let me...a little bit more here.1355

Let's go to fructose 6-phosphate, sedohep, sedohep, and here is another fructose 6-phosphate, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 6.1364

OK, we are good; now, the enzymes that take care of this... actually, let me do the enzymes in blue.1380

I will tell you what is going on; let me just go ahead and write everything in.1388

Transketolase, transaldolase- these enzymes are absolutely extraordinary.1395

They do the extraordinary.1400

It is just really...when you see what they do, it is just...it is amazing, and another transketolase reaction right here.1404

OK, now, let's go ahead and write in red glucose 6-phosphate.1414

That ends up going there; this ends up going here.1423

This ends up going here; this ends up going here.1426

This ends up going here; OK, here is what is happening.1429

Let me go ahead and do this in black.1432

The transketolase enzyme, it transfers a 2-carbon fragment; it is what it does, and we will talk about the reaction in just a minute, but I wanted you to see what actually happens with this whole non-oxidative phase.1438

This is the non-oxidative phase that we are going to be discussing here; let me just write that.1452

Sorry about that; I did not write it on top, so this is the non-oxidative phase.1456

This is where the pentose phosphates that is formed - the ribose 5-phosphate and the ribulose 5-phosphate - are actually recycled back to glucose 6-phosphate to keep going in that non-oxidative cycle in order to keep producing the NADPH.1461

OK, here is what happens; in the first transketolase reaction - let me do this in...that is fine, I will do it in red - ribose 5-phosphate and xylulose 5-phospahte react and 2 things get produced.1479

The 2 things that come out of this reaction are glyceraldehyde-3-phosphate and sedoheptulose 5-phosphate.1495

This is a 5 carbon; this is a 5 carbon.1500

There is 10 carbons altogether; what they produce is a 3-carbon and a 7-carbon sugar.1503

That is what is amazing; it is the carbons that again, they switched around.1509

It is 3 and 7; it is still 10.1511

Those come together, they form erythrose 4-phosphate, which is a 4 carbon and fructose 6-phosphate, which is a 6 carbon.1514

So, we went 5-5 which is 10, 7-3, which is 10 to 6-4, which is 10.1522

Now, this fructose 6-phosphate is converted to glucose 6-phosphate by the enzymes in the glycolytic pathway, remember?1527

And then, we are trying to get to glucose 6-phosphate because we are recycling it back to the oxidative phase.1533

OK, now, this erythrose 4-phosphate and the xylulose 5-phosphate - this is a 4 carbon - another xylulose 5-phosphate, they react - this is 9 - to produce a fructose 6-phospahte, which is a 6-carbon and glyceraldehyde-3-phosphate, which is a 3-carbon.1541

Again, the carbons are conserved, 9 carbons.1560

That is 1/2 of the mirror image; well, the same thing happens on the other end.1564

Ribose 5-phosphate and xylulose 5-phosphate - a 5 and 5 carbon - produce sedoheptulose 7-phosphate, glyceraldehyde 3-phosphate, which is a 7-3 carbon- 7-carbon sugar, 3-carbon sugar.1570

They react in the transaldolase reaction to form a 6-carbon sugar and a 4-carbon sugar, fructose 6-phosphate and erythrose 4-phosphate.1580

The erythrose 4-phosphate - just like this other side, this is happening in tandem - reacts with xylulose 5-phosphate.1590

So, we have 4-carbon and a 5-carbon, which is 9 carbons.1597

They produce a 6-carbon fructose 6-phosphate, a 3-carbon glyceraldehyde-3-phosphate.1600

Now, the glyceraldehyde-3-phosphates that are produced - this is 3-carbon, this is 3-carbon - they form a 6-carbon, a fructose 6-phosphate, which is converted to glucose 6-phosphate, and now, we can start the oxidative phase again.1605

What happens is this; I will do this in red, 1, 2, 3, 4, 5 and 6.1618

6 pentose phosphates, which is 30 carbons, are converted through this pathway to 1, 2, 3, 4, 5, 6-carbon sugars.1633

Once again, 1, 2, 3, 4, 5, 6, 5-carbon sugars, which is 30 carbons, are converted to 5 6-carbon sugars, which is again 30 carbons.1657

The carbons are conserved, but we changed them to fructose 6-phospahate, so that fructose 6-phosphate can be converted to glucose 6-phosphate and start this oxidative phase of the cycle again, in order to produce the NADPH - this is absolutely amazing - in application of the transketolase reaction once, the transaldolase reaction once and the transketolase reaction a second time to actually do this.1667

This is the non-oxidative phase of the pentose phosphate pathway.1691

It is absolutely beautiful; you will see something like this in your book.1695

Either use this one or the illustration in your book to make sure you understand.1699

What is happening is this and this are coming together to form this and this; this and this are coming together to form this and this.1703

This and this coming together to form this and this, and so on.1708

5 and 5 is 10; 3 and 7 is 10.1712

4 and 6 is 10; 5 and 4 is 9.1715

3 and 6 is 9; OK, the carbons are conserved.1718

They are just being shifted back and forth, transferred from one substrate to another.1722

Now, let's take a look at the individual reactions, the transketolase and the transaldolase.1726

Let's see.1732

OK, there we go; let's go back, and now, let's go back to black.1738

This is going to be the general transketolase reaction.1743

What you have is 1, 2, 3, and, of course, I will just put R1 here.1756

We have an OH; we have an H.1765

We have that, and we have another OH and an H2.1769

This is going to be added to some...let's see.1774

We have got...that is fine; we will just go ahead and do C.1783

We will do R2, aldehyde and that.1787

Notice, we have this ketose and TPP.1791

Yes, I do not think I am going to do the mechanism here.1800

OK, TPP, this is the transketolase, and what we end up with is COO, R1, H+, C, C, C, R2, OH, H.1803

This is there, and we get another OH and an H2.1828

This is the ketose donor.1832

This is the aldose acceptor; I will tell you what that means in just a minute.1839

OK, P, notice, TPP is required coenzyme, thiamine pyrophosphate, we saw it a little bit earlier.1846

OK, the enzyme transketolase, what it does is it catalyzes the transfer of a 2-carbon fragment from a ketose to an aldose, in other words, from a ketone sugar to an aldehyde sugar.1854

Here is our 2-carbon fragment.1892

This is our ketose; this is our aldose.1896

We are moving this over to here; notice, this moves.1899

This molecule becomes that molecule, and this aldose accepts, that is why aldose acceptor.1905

It accepts the 2-carbon fragment; the ketose donates that 2-carbon fragment.1910

Nothing changes; here is that 2-carbon fragment.1914

This molecule has turned into this molecule; this has given this 2-carbon fragment over to that.1917

That is what the transketolase enzyme does.1925

OK, now, let's go ahead and take a look at the first transketolase reaction.1929

Let me see; should I...yes, that is fine.1936

I guess I can do it on here; yes, I will go ahead and do it here.1940

Let's go ahead and go to blue, so 1, 2, 3, 4, 5; I have got 1, 2, 3, 4, 5.1945

OK, I have got OH; I have got O.1953

I am going to skip all of the hydrogens, OH, and I have got O; and I have got - excuse me - the phosphate.1958

This is our ketose; this is the general reaction.1967

Now, we are going to look at our specific reaction; this is our ketose.1971

Now, we have our aldose, which is going to be 1, 2, 3, 4, 5.1976

We have the xylulose 5-phosphate reacting with the ribose 5- phosphate.1981

That was the first reaction in the thing that we just drew in the top right or the top left.1986

This is an aldose; this is an aldehyde sugar.1991

We have OH, OH, OH, O and phosphate - those 2 - and it is going to go to...that is what is going to transfer over.1995

Let me go back to blue here, make sure I am blue.2012

OK, I have got C, C, C, form glyceraldehyde-3-phosphate, O phosphate plus our sedoheptulose 7-phosphate.2017

Let's go 1, 2, 3, 4, 5, 6, 7.2035

This is the fragment that moved over; that is the OH.2041

That is the carbonyl; this one, actually, is over here, and then, we have OH.2046

We have OH; we have OH, and we have our phosphate.2053

Here is what was moved; this went from here.2059

It was transferred over to this one; 5 carbons + 2 carbons gives us a 7-carbon.2064

Where do I write this?2073

This is our xylulose 5-phosphate; this is our ribose 5-phosphate.2077

This is our glyceraldehyde-3-phosphate, and this is our sedoheptulose 7-phosphate.2083

That is the first transketolase reaction; that is the first step of what we did when we saw it go like this.2091

These two switched; this gives it over to this to become this.2097

OK, now, let's go ahead and take a look at the transaldolase reaction.2102

Let me go back to blue here; OK, now, we have then, for the transaldolase reaction.2109

Alright, we have got our 7-carbon fragment, 1, 2, 3, 4, 5, 6, 7.2122

Let me go ahead and put everything...you know what, I need to make more room here, 1, 2, 3, 4, 5, 6, 72134

This is going to be OH; this is going to be a carbonyl.2153

This is going to be OH, and then, we have 1, 2, 3.2158

Yes, and then, we have our O phosphate.2162

This is our sedohep 7-phosphate; this is going to react, now, with the glyceraldehyde-3-phospahte, which is a 3-carbon, C, C, C, OH and O, P, phosphate.2170

What it is going to form is the following.2188

1, 2, 3 and then, we are going to be 3 and 6.2193

Yes, what is going to move...well, let me just draw it out first, and then, I will tell you what moves.2197

We have got 1, 2, 3, 4.2200

That is that, OH, OH, O, P, and then, plus our fructose 6-phosphate, which is going to be 6-carbon, 1, 2, 3, 4, 5 and 6.2206

I hope I have enough room here, OH, carbonyl, OH, OH, OH and O and P.2224

Here is what ended up moving over.2235

These 3 were moved over onto this to make this.2239

That is this right here; this is what the transaldolase reaction does.2248

It takes a 3-carbon fragment, pushes it onto the glycerldehyde-3-phosphate to create a 6-carbon fragment.2253

I have started off with a 7-carbon sugar, now, I am left with a 4-carbon sugar.2259

This became that; this became that upon transfer of this to that.2264

OK, now, let me go ahead and write the transaldolase reaction.2272

The transaldolase reaction condenses - right, when we are putting 2 molecules together, it is a condensation reaction - a 3-carbon fragment with the glyceraldehyde-3-phosphate to from our fructose 6-phospahte.2280

Here, we have fructose 6-phosphate; here, we have our erythrose 4-phosphate.2312

Here, we have glyceraldehyde-3-phosphate, and here, we have our sedoheptulose 7-phosphate- there we go.2320

Fructose 6-phospahte and a tetrose is a 4 carbon sugar- that is it.2332

7-3, 10, 4-6, 10, we wanted to produce a 6-carbon sugar, so that it can become glucose 6-phosphate.2343

OK, that is the transaldolase reaction; now, let's go ahead and look at the final transketolase reaction.2350

I think I will go ahead and do this one in black.2359

Now, we are going to react a xylulose 5-phosphate with the erythrose to actually form our next fructose.2363

Let's go ahead and do 1, 2, 3, 4, 5...we have got 1, 2, 3, 4, 5, and this is our ketose.2376

Remember, we are transferring a 2-carbon fragment.2385

This is OH, and this is O; and this is phosphate, and we are going to react this with our 4-carbon, 1, 2, 3, 4.2390

This is an aldose, OH, OH and our O, P.2398

OK, you know what, let me write these out.2407

This is xylulose 5-phosphate, and this is our erythrose 4-phospahte.2411

Let me go back to black, and what we are going to end up transferring, of course, is this onto this because that is what transketolase does.2419

It transfers a 2-carbon fragment from a ketose to an aldose- transketolase.2427

It transfers a 2-carbon fragment from a ketose to an aldose.2432

Here is our ketose; here is our aldose.2438

So, what we are going to end up forming, we are going to be left with 3-carbon fragment, which is going to be our glycerldehyde-3-phosphate.2442

OK, we produce an aldose, and we produce a ketose, OH.2449

This is O, and this is our phosphate.2455

This is glyceraldehyde-3-phosphate - now, let me go back - + fructose 6- phosphate, 1, 2, 3, 4, 5 and 6.2459

What we have is OH; we have that.2471

We have that; we have this, and we have this, and we have this.2475

Here we go; we are down to fructose 6-phosphate again.2483

Those 3 sequential reactions produce the fructose 6-phosphate.2488

The 3 sequential reactions on the mirror image produce that again.2494

Here, we had another 2-carbon fragment.2498

That ended up over here.2507

Another 2-carbon fragment is transferred from a ketose to an aldose.2512

If you know nothing else, recognize that.2531

A transketolase reaction takes a 2-carbon fragment from a ketose to an aldose.2534

It just moves it over- that is it.2538

And the final word on the pentose phosphate pathway, the enzymes, all these enzymes of the pentose phosphate pathway, they are cytosolic.2542

There you go; this closes out our discussion of glycolysis and gluconeogenesis and the pentose phosphate pathway.2559

Thank you so much for joining us here at Educator.com; we will see you next time for a discussion of the citric acid cycle, bye-bye.2568

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