Principles of Biology - Biology 102 Lake Tahoe Community College
Spring Quarter Instructor: Sue Kloss
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Ch. 39 Control Systems in Plants
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I Signal transduction pathways.
A. signals elicit a response
B. General model of cell
C. Reception
D. Transduction
1. receptors
2. weak signals amplified
E. Response
1. signal transduction pathways lead to regulation
2. two main mechanisms
3. transcriptional
4. posttranslational modification
F. De-etiolation proteins
II. Plant Hormones
A. Phototropism
1. cells on darker side elongate faster
2. if light is uniform
3. hormones regulate plant growth;
B. 6 major types of plant hormones and classes
1. produced in very small amts
2. Auxins
3. Cytokinins
4. Giberellins.
5. Brassinosteroids
6. Abcisic acid
6. Ethylene triggers fruit ripening.
C. Growth Responses and Biological Rhythms
1. tropisms
D. Internal clocks -
1. gene that controls clock
2. adapt for temperature
E. Plants mark season
1. flowering
2. Plants use photoperiod
3. flowering and other responses
F. How do plants measure photoperiod?
1. phytochromes
G. Plant defense
1. herbivory -
2. pathogens-
Study Questions:
Ch. 39
1. Compare the growth of a plant in darkness (etiolation) to the characteristics of greening (de-etiolation).
2. Describe the signal pathways associated with de-etiolation.
3. Describe the role of second messengers in the process of de-etiolation.
4. Describe the two main mechanisms by which a signaling pathway can activate an enzyme.
5. Explain, using several examples, what researchers have learned about the activity of plant hormones by study of mutant plants
6. For the following scientists, describe their hypothesis, experiments, and conclusions about the mechanism of phototropism:
a. Charles and Francis Darwin
b. Peter Boysen-Jensen
c. Frits Went
7. List 8 classes of plant hormones, and describe one or two major functions of each.
8. Describe how abscisic acid (ABA) helps prepare a plant for winter.
9. Describe the effects of ABA on seed dormancy and drought stress.