Lecture 12 - Plant Signals and Behavior Flashcards
(83 cards)
1
Q
how do plants respong to signals from the environment
A
altering growth and development
2
Q
respond to sunlight
A
phototaxis
3
Q
negatively respond to gravity
A
negative gravitaxis
4
Q
positively respond to gravity
A
positive gravitaxis
5
Q
example of chemotaxis
A
bending of dodler as response to chemicals released by host
6
Q
morphological adaptations for growing in darkness
A
etiolation
7
Q
shoots and roots grow normally after exposure to light
A
de-etiolation
8
Q
stages of cell signal processing
A
- reception
- transduction
- response
9
Q
detected by receptors
A
internal and external signals
10
Q
proteins that change in response to specific stimuli
A
receptors
11
Q
transfer and amplify signals from receptors to proteins that cause responses
A
second messengers
12
Q
relay proteins and second messengers
A
transduction
13
Q
activation of cellular responses
A
Response
14
Q
signal transduction pathway leads to what
A
regulation of one or more cellular activities
15
Q
signal transduction pathway can occur by what
A
- transcriptional regulation or
- post-translational modification
16
Q
what is the receptor in de-etilation
A
phytochrome capable of detecting light
17
Q
two types of messenger that play an important role in de-etiolation
A
- Ca 2+ ions
- cyclic GMP (cGMP)
18
Q
what does the cGMP activate
A
protein kinase 1
19
Q
what does Ca 2+ influx activate
A
protein kinase 2
20
Q
where protein kinase 1 acts
A
transcription factor 1
21
Q
where protein kinase 2 act
A
transcription factor 2
22
Q
after translation of genes activated by transcription factor 1 and 2
A
de-etiolation (greening) response proteins
23
Q
involves modification of existing proteins int he signal response
A
post-translational modification
24
Q
what does modification often involve
A
phosphorylation of specific amino acids
25
what do the second messengers cGMP and Ca2+ do in post-translational modification of preexisting proteins
activate protein kinases directly
26
how do protein phosphatases "switch off" the signal transduction pathways
by dephosphorylating proteins
27
how does transcriptional regulation happen
specific transcription factors bind directly to specific regions of DNA and control transcription of genes
28
transcription factors are either..
1. activators
2. repressors
29
de-etiolation activates enzymes that:
1. function in photosynthesis directly
2. supply the chemical precursors for chlorophyll production
3. affect the levels of plant hormones that regulate growth
30
help coordinate growth, development, and responses to stimuli
plant hormones
31
amount of plant hormones produced
very low concentrations
32
where do plant responses depend
1. amount of concentration of specific hormones
2. combination of hormones present
33
each hormone has __ effects
multiple
34
multiple hormones can influence a __ __
single process
35
major plant hormones
1. auxin
2. cytokinins
3. gibberellins
4. abscisic acid
5. brassinosteroids
6. ethylene
7. jasmonates
8. strigolactones
36
hormones responsible for ripening
ethylene
37
any response resulting in curvature of organs toward or away from a stimulus
tropism
38
plant's response to light
phototropism
39
conducted experiments on phototropism
1. Charles Darwin
2. Francis Darwin
(late 1800s)
40
what did Charles and Francis Darwin observe
grass seedling could bend toward light only if the tip of the coleoptile was present
41
demonstrated that the signal that respond to light was a mobile chemical substance
Peter Boysen-Jensen (1913)
42
set up of Charles and Francis Darwin
1. tip removed
2. opaque cap
3. transparent cap
4. opaque shield over curvature
43
set up of Boysen-Jensen
1. gelatin (permeable)
2. mica (impermeable)
44
- any chemical that promotes elongation of coleoptiles
- produced in shoot tips and is transported down the stem
auxin
45
common auxin in plants
indoleacetic acid (IAA)
46
move the hormone from the basal end of one cell into the apical end of the neighboring cell
auxin transporter proteins
47
role of auxin in cell elongation
acid growth hypothesis
48
acid growth hypothesis
auxin stimulates proton pumps in the plasma membrane
49
what do proton pumps do in the cell wal
lower the pH in cell wall
50
enzymes that loosen the wall's fabric
expansins
51
mechanism of cell elongation in response to auxin
1. proton pump activity increases
2. acidity increases
3. low pH activates expansins
4. cell wall-loosening enzymes cleave cross-linking polysaccharides
52
cell elongation in response to auxin
5. sliding cellulosw microfibrils allow cell to elongate
53
Auxin's role in plant development
1. Polar transport of auxin plays a role in pattern formation of the developing plant
2. Reduced auxin flow from the shoot of a branch stimulates growth in lower branches
3. Auxin transport plays a role in phyllotaxy (the arrangement of leaves on the stem)
4. Polar transport of auxin from leaf margins directs leaf venation pattern
5. The activity of the vascular cambium auxin transport
54
practical uses for auxins
1. stimulates adventitous roots
2. ued in vegetative propagation of plants by cuttings
3. overdose of synthetic auxins can kill plants
55
named because they stimulate cytokinesis
cytokinins
56
where are cytokinins produced
actively growing tissues such as roots, embryos, and fruits
57
interact in the control of apical dominance
- cytokinins
- auxin
- strigolactone
58
terminal bud's ability to suppress development of axillary buds
apical dominance
59
how do cytokinins slow aging of some plant organs
- inhibiting protein breakdown
- stimulating RNA and protein synthesis
- mobilizing nutrients from surrounding tissues
60
affects stem elongation, fruit growth, and seed germination
gibberellins
61
gibberellins is important in:
1. stem elongation
2. fruit growth
3. seed germination
62
where is gibberellins produced
young roots and leaves
63
what does gibberellins stimulate in stems
elongation and cell division
64
in many plants, what hormones must be present for fruit development
auxin and gibberellins
65
after water is imbibed, release of gibberellins signal seeds to what
germinate
66
hormone that slows growth
abscisic acid (ABA)
67
two of the many effects of ABA
1. seed dormancy
2. drought tolerance
68
ensure that the seed will germinate only in optimal conditions
seed dormancy
69
how is ABA removed and dormany is broken
1. heavy rain
2. light
3. prolonged cold
70
can be caused by inactive or low levels of ABA
precocious (early) germination
71
tip of plant
coleoptile
72
primary internal signal that enables plants to withstand drought
abscisic acid (ABA)
73
causes stomata to close rapidly
ABA accumulation
74
- chemically similar to sex hormones of animals
- induce cell elongation and division in stem segments
- slow leaf abscission and promote xylem differentiation
brassinosteroids
75
what does brassinosteroids do
1. induce cell elongation and division in stem segments
2. slow leaf abscission and promote xylem differentiation
76
- stimulates cell elongation
- regulates branching and organ bending
auxin
77
- stimulate plant cell division
- promote later bud growth
- slow organ death
cytokinins
78
- promote stem elongation
- helps seeds break dormancy and use stored reserves
gibberellins
79
- promotes stomatal closure in response to drought
- promotes seed dormancy
abscisic acid
80
mediates fruit ripening and the triple response
ethylene
81
- chemically similar to the sex hormones of animals
- induce cell elongation and division
brassinosteroids
82
- mediate plant defenses against insect herbivores
- regulate a wide range of physiological processes
jasmonates
83
regulate apical dominance, seed germination, and mycorrhizal associations
strigolactones
