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Plant Hormones and Tropisms
- Auxins are produced in the apical meristem of plants and stimulate stem elongation and phototropism as well as fruit development. Indoleacetic acid (IAA), an auxin, occurs naturally in plants.
- Cytokinins are produced in the roots of plants and stimulate cell division and differentiation and play a role in apical dominance.
- Gibberellins promote the elongation of plant stems and are responsible for the rapid growth of a floral stalk, which is known as bolting.
- Ethylene is a hormone that is a gas. It stimulates fruit ripening, leaf abscission and promotes apoptosis of plant cells.
- Abscisic Acid (ABA) promotes seed dormancy, preventing seeds from germinating until conditions are favorable. ABA also stimulates the closure of stomata in leaves when conditions are dry.
- A tropism is a response in which a plant turns toward or away from a stimulus. Types of tropism include phototropism, gravitropism and thigmotropism.
Plant Hormones and Tropisms
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
- Plant Cell Signaling
- Plant Cell Signaling Overview
- Step 1: Reception
- Step 2: Transduction
- Step 3: Response
- Second Messengers
- Protein Kinases
- Auxins
- Cytokinins and Gibberellins
- Ethylene
- Abscisic Acid
- Tropisms
- Phytochromes and Photoperiodism
- Phytochromes: PR and PFR
- Circadian Rhythms
- Photoperiod
- Photoperiodism
- Gerner & Allard
- Short-Day Plant
- Long-Day Plant
- Example 1: Plant Hormones
- Example 2: Cytokinins & Gibberellins
- Example 3: Match the Following Terms to their Description
- Example 4: Hormones & Cell Response
































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