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Biology II > ch. 39 pt. 1 > Flashcards

ch. 39 pt. 1 Flashcards

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1
Q

how do plants respond to signals from the environment?

A

altering growth and development

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2
Q

what do signal transduction pathways link?

A

signal to response

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3
Q

steps of signal transduction pathway

A

reception of signal, transduction, response

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4
Q

what happens to a potato left growing in darkness

A

process pale stems, unexpanded leaves, and short roots
- etiolation

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5
Q

etiolation

A

morphological adaptations for growing in darkness

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6
Q

etio

A

cause

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7
Q

what happens after etiolated potato is exposed to light

A

undergoes de-etiolation, shoots/roots grow normally

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8
Q

how do proteins function?

A

by changing shape

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9
Q

what do receptor proteins do in response to the stimulus

A

change shape

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10
Q

receptor in de-etiolation

A

phytochrome capable of detecting light

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11
Q

second messengers

A

transfer/amplify signals from receptors to other proteins that cause responses

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12
Q

2 types of second messengers

A

calcium ions (Ca2+) and cyclic GMP (cGMP)

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13
Q

how does the phytochrome receptor respond to light?

A
  • opening Ca2+ channels, increase Ca2+ levels in cytosol
  • activating enzyme that produces cGMP
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14
Q

phytochrome

A

plant color

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15
Q

how is GMP different from cGMP

A

GMP undergoes dehydration synthesis to from cGMP

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16
Q

ase

A

enzyme

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17
Q

kin

A

movement

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18
Q

what does a kinase do

A

catalyze transfer of a phosphate group from ATP to specified molecule
- substrate +ATP -> ADP + substrate

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19
Q

de-etiolation signal pathway process

A
  1. phytochrome activated by light
  2. cGMP produced and Ca2+ channel opened, activate protein kinases
  3. protein kinases activate transcription factors in nucleus
  4. trasncription
  5. translation
  6. de-etiolation
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20
Q

what does a signal transduction pathway lead to

A

regulation of one or more cellular activities

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21
Q

what do most responses to stimulation involve

A

change in activity of enzymes

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22
Q

how can a change in activity of enzymes (response) occur

A
  1. transcriptional regulation
  2. post-translational modification
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23
Q

post-translational modification

A

modification of existing proteins in signal response
- often involves phosphorylation of specific amino acids
- cGMP and Ca2+ directly activate protein kinases

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24
Q

phosphorylation

A

activation

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25
Q

dephosphorylation

A

inactivation

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26
Q

how do protein kinases often work?

A

in a cascade linking initial stimuli to gene expression through phosphorylation of transcription factors

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27
Q

transcriptional regulation

A
  • transcription factors bind directly to specific regions of DNA and control transcription of specific genes
  • some transcriptional factors activators that increase transcription
  • others are repressors that decrease transcription
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28
Q

what does de-etiolation activate:

A

enzymes that
1. function in photosynthesis directly
2. supply chemical precursors for chlorophyll production
3. affect levels of plant hormones that regulate growth

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29
Q

what do plant hormones do

A

help coordinate growth, development, and responses to stimuli

30
Q

what are plant hormones

A

chemical signals that modify or control specific physiological processes within a plant

31
Q

what are plant hormones also called

A

plant growth regulators

32
Q

growth promoters

A

auxins, cytokinins, gibberellins

33
Q

growth inhibitors

A

ethylene, abscissic acid

34
Q

are plant hormones produced in high or low concentrations

A

low

35
Q

effects of hormones

A

each hormone has multiple effects, but multiple hormones can influence single process

36
Q

what do plant responses to hormones depend on

A

concentration and combination of specific hormones

37
Q

major plant hormones

A
  1. auxin
  2. cytokinins
  3. gibberellins
  4. abscisic acid
  5. ethylene
  6. brassinosteroids
  7. jasmonates
  8. strigolactones
38
Q

overview of auxin

A

stem elongation, formation of lateral adventitious roots, phototropism/gravitorpism

39
Q

cytokinins overview

A

cell division in shoots/roots, modifies apical dominance to promote lateral bud growth, movement of nutrients into sink tissues

40
Q

gibberellins overview

A

stem elongation, pollen development, seed development/germination, sex determination

41
Q

abscisic acid overview

A

inhibits growth, stomatal closure during drought stress, seed dormancy, senescence

42
Q

ethylene overview

A

ripening of fruit, leaf abscission, senescence

43
Q

brassinosteroids overview

A

cell expansion/division in shots, xylem/phloem differentiation

44
Q

jasmonates overview

A

fruit ripening, floral development, nectar secretion, response to herbivory/pathogen invasions

45
Q

strigolactones overview

A

seed germination, attraction of mycorrhizal fungi to root

46
Q

tropsim

A

any response resulting in curvature of organs toward or away from stimulus
- phototropism
- thigmotropsim
- gravitropism

47
Q

Darwin and Darwin

A

phototropism only occurs when tip is illuminated

48
Q

Boysen-Jensen

A

phototropism occurs when tip is separated by permeable (not impermeable) barrier

49
Q

auxin

A

any chemical that promotes elongation of coleoptiles

50
Q

indolacetic acid

A

common auxin in plants

51
Q

what is the transport of auxin referred to as?

A

polar
- produced in shoot tips, transported down the stem

52
Q

what do auxin transporter proteins do

A

move hormone from basal end of one cell into apical end of neighboring cell

53
Q

does the direction of auxin change in response to gravity?

A

no

54
Q

acid growth hypohtesis

A
  • auxin stimulates proton pumps in plasma membrane
  • H+ moves into cell, lowers pH in cell wall and increases membrane potential
  • reduced pH activates expansins
  • osmotic uptake of water into cell increases turgor pressure
  • increased cell wall plasticity combined with increased turgor pressure enables cell to elongate
55
Q

expansins

A

enzymes that loosen the fabric of the cell wall

56
Q

what does auxin also do?

A

alter gene expression and stimulates sustained growth response

57
Q

reduced auxin flow from the shoot stimulates what?

A

growth in lower branches

58
Q

what does auxin transport play a role in?

A
  • phyllotaxy
59
Q

what does polar transport of auxin from leaf margins direct?

A

leaf venation pattern

60
Q

what is the activity of the vascular cambium under control of?

A

auxin

61
Q

what is the organization of female angiosperm gametophytes likely regulated by?

A

auxin gradient

62
Q

auxin functions

A
  • vascular cambium
  • organization of female angiosperm gametophytes
  • plant development
  • acid growth/cell elongation
63
Q

indolebutyric acid

A

auxin that stimulates adventitious roots, used in vegetative propagation of plants by cuttings

64
Q

synthetic auxins

A

used in herbicides (2,4-D) that kill edicots by causing hormonal overdose
- monocots able to inactivate these hormones

65
Q

what do developing seeds produce?

A

auxin - promotes fruit development

66
Q

cytokinins

A

stimulate cytokinesis

67
Q

where are cytokinins produced

A

actively growing tissues (roots, embryos, fruits)

68
Q

how does cytokinins work together with auxin?

A

to control cell division and differentiation

69
Q

apical dominance

A

terminal bud’s ability to suppress development of axillary buds

70
Q

what is apical dominance under the control of?

A

sugar, cytokinins, auxin, and strigolactone

71
Q

what happens when the apical bud is removed:

A
  • increases sugar availability
  • decreases auxin/strigolactone levels
  • initiates axillary bud growth
72
Q

cytokinins and anti-aging of plant organs

A
  • inhibiting protein breakdown
  • stimulating RNA and protein synthesis
  • mobilizing nutrients from surrounding tissues

Biology II (43 decks)

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