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Plant Phys AA😩 > Final thoughts- > Flashcards

Final thoughts- Flashcards

1
Q

flux rate can be defined as-

A

driving force/resistence

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2
Q

I’d review Fick’s law (section 2.2)

A

nice

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3
Q

Osmosis is diffusion of

A

free water down its concentration gradient

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4
Q

solutes make water less

A

free

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5
Q

Pr- what form, absorbs what light

A

inactive form, absorbs red light, so found in adsence of red light (dark or shade)

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6
Q

Pfr-
what form, absorbs which light

A

active form, absorbs far red light (present in full light) relatively unstable

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7
Q

Absorption of red light by pigment causes

A

conformational change in protein
Chromophore (pigment where attaches to protein)
Cis isomer becomes the trans isomer

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8
Q

Light-seeking behavior mediated by who?

A

phytochrome

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9
Q

How is phytochrome activated?

A

Phytochrome auto-phosphorylates-

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10
Q

What conditions favor etiolation?

A

R:FR ratio tells all

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11
Q

Which form of phytochrome leads to etiolation?

A

Pr form

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12
Q

Light status (in terms of phytochrome) at top of canopy

A

lots of Pfr

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13
Q

Light status (in terms of phytochrome) at bottom of canopy

A

lots of Pr

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14
Q

Pfr

A

The biologically active form of phytochromes that absorbs far-red light

(with a peak around 730 nanometers)

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15
Q

Pr

A

The biologically inactive form of phytochrome that absorbs red light

(with a peak around 660 nanometers)

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16
Q

With low quality light:

A

-R:FR is low
-phytochrome pool mostly Pr (inactivated)
-seeds wont germinate
-seedlings etiolate

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17
Q

In full sun-

A

R:FR ratio high
-seeds germinate
-seedlings allocate to photosynthesis

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18
Q

What is PIF?

A

PIF- phytochrome interacting factors, transcription factors

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19
Q

Phytochrome binds to PIF removing it from upstream promotor regions- what effect will this have?

A

Effect depends on what PIF was doing originally-

If it was activating a gene the gene will be turned off by Pfr.

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20
Q

If Phytochrome (Pfr) was activated and PIF was suppressing a gene, what change will occur?

A

The gene will be turned on by Phytochome (Pfr)

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21
Q

Are PIFs on genes in the dark?

A

Yes, so depending on if them being there is repressing or activating will change what happens when Pfr shows up

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22
Q

What is the relationship between Pfr and PIFs?

A

Antagonistic, Pfr will remove PIFs from genes

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23
Q

If you observe etiolation growth, do you expect PIFs to induce or repress?

A

Activate

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24
Q

If you observe seeds breaking dormancy, do you expect PIFs to induce or repress?

A

repress

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25
Q

If you observe conversion of etioplasts to chloroplasts, do you expect PIFs to induce or repress?

A

repress

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26
Q

If you observe seedling hypocotyl elongation, do you expect PIFs to induce or repress?

A

promote
(branching repressed?)

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27
Q

What type of molecule is a PIF?

A

transcription factor

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28
Q

Blue light responses mediated by three different types of photoreceptor molecules:

A

1) Phytochromes
2) Cryptochromes
3) Phototropins

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28
Q

Phytochromes-

A

respond to red light (some responses mediated by blue light)

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29
Q

Cryptochromes-

A

Blue light (got flavin, involved with circadian rhythms) inhibition of hypocotyl elongation, flowering, cotyledon expansion

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30
Q

Phototropins-

A

phototropism, chloroplast movement

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31
Q

What type of molecule is phytochrome?

A

protein kinase

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32
Q

What light activates cryptochromes?

A

Blue light

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33
Q

inhibition of hypocotyl elongation controlled by who?

A

Cryptochromes

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34
Q

Who is phototropism primarily mediated by?

A

Phototropins

35
Q

Phototropins have also

A

flavin chromophores that sense light, cause conformational change in protein, auto phosphorylation

36
Q

Activated phototropins cause the hormone ______ to

A

auxin to accumulate on shady side of stem, resulting in positive phototropism

37
Q

Auxin causes cell elongation which bends

A

the plant (towards light source)

38
Q

Phototropins also mediate chloroplast movement in response to

A

light

39
Q

in the absence of drought, stomata respond primarily to

A

ambient light

40
Q

For stomatal opening, who drives K+ into the cell?

A

H+ATPase pumps protons out creating charge gradient, so potassium ions are drawn into guard cells

41
Q

How does auxin accumulate on the shady side of a stem?

A

by phosphorylating/ deactivating auxin transporters (ABC proteins) on the sunny side of the stem

42
Q

What are the five traditional classes of plant hormones:

A

-auxins
-cytokinins
-ethylene
-abscisic acid
-gibberellins

43
Q

Where are auxins produced and how do they move?

A

produced in shoot apex and leaves, moves down but not up the plant (basipetal movement)

44
Q

-auxin accumulates at bottom side of lateral shoot or root.

A
45
Q

Do plant hormones react locally or over long distances in the plant?

A

Both

46
Q

What is the general auxin structure?

A

indole ring and acetic acid side chain

47
Q

Effect of auxin on cell frowth exactly opposite in shoots bc roots.

A

In roots, auxin inhibits elongation of cells (drift due to starch?)

48
Q

PIN proteins transport to allow auxins to

A

flow from one cell to another, down and through

49
Q

Positive root geotropism,

A

moves toward gravity, auxins inhibit cell growth

50
Q

Auxin also involved with apical domaince

A

branching and shoots at shoot apex (if cut off tip)

51
Q

auxin helps form vascular strands

A

to new leaf primordia or in damaged stems (also stimulates differentiation into vascular cambium)

52
Q

If seeds removed, fruit wont develop.

Addition of what hormone to fruit allows for seedless varieties?

A

auxin

53
Q

Cytokinins general structure

A

adenine base (very nitrogenous)

54
Q

the auxin:cytokinin ratio regulates morphogenesis

A

high auxin: roots
Intermediate: callus
Mid: shoots

55
Q

Plant cells stem cells can go back?

A

Yes

56
Q

Cytokinins also inhibit leaf

A

senescence

could be bad if not use bc prep for winter or something

57
Q

ethylene plays a major role in

A

fruit ripening, leaf abscission (leaf fall off), and inhibition of cell expansion

(not class of hormones, one molecule)

58
Q

Main roles of abscisic acid

A

1) suppression of seed germination
2) stomatal closure

59
Q

main roles of gibberellins

A

longitudinal growth and breaking seed dormancy

60
Q

ethylene fruit ripening what happen

A

breakdown of chlorophyll, becomes starch

61
Q

ethylene and auxin are what qith respect to leaf abscission?

A

antagonistic (ethylene promotes it)

62
Q

Maize mutant insensitive to ABA (absicisc acid) what happens

A

seeds grow while still on plant and not ripened or dispersed

63
Q

Some seeds (red mangrove plant) seeds germinate while still in the fruit, why?

A

they do this bc frequently flooded, so they can drop right into mud

64
Q

ABA upregulated in leaf under drought conditions- signal to close stomata

How work? (hint calcium involved)

Think of calcium as more of a messenger than a charge gradient changer

A

1) ABA causes Ca2+ channels to open causing influx
2) Ca+ causes anion channel to open, causing efflux
3) membrane depolarization causes K+ channels to open
4) water leaves and cell loses turgor

65
Q

Dwarf plant phenotypes can be rescuded by addition of what hormone?

A

gibberellins

66
Q

Gibberellins are what to ABA?

A

Antagonistic

67
Q

What are “secondary compounds” basically defined as?

A

Not involved in growth and development, often used for defense

68
Q

Terpenes structure what, and hydrophobicity/hydrophilicity

A

molecules built from isopentyl diphosphate IPP

generally hydrophobic from all the C-H bonds

69
Q

Terpenes use what two synthesis pathways in plants?

A

mevalonic acid pathway and MEP pathway

70
Q

For Mevalonic acid pathway-

A

-The 5 carbon backbone of IPP is build up from acetyl CoA (come straight from cellular respiration)

71
Q

For the MEP pathway for biosynthesis, uses who for carbon from what cycle

A

G3P from the C3 cycle which is joined to pyruvate form glycolysis precursors of IPP

72
Q

Do terpenes have rings?

A

hell yeah brother

73
Q

Describe terpenes vs terpenoids

A

terpenes only hydrocarbons
terpenoids have oxygens in them

74
Q

Terpenes include

A

hormones carotenoids pigments and essential oils

-serve anti-herbivory functions
-often aromatic hence smell
-usually volatile

75
Q

Glycosides consist of

A

sugar bound to something else, many feature glucose linked to terpenoid (have saponins, amphipathic)

76
Q

What are phytoecdysones?

A

insect compounds that induce herbivore molting

77
Q

Some terpenes can be polymers

A

such as rubber

78
Q

Keep in mind there are many types of glycosides

A

Many discourage herbivory or happen to be toxic to us

79
Q

Phenolics structure-

A

aromatic rings with hydroxyl groups

80
Q

Shikimic acid pathway

A

starts with PEP, pathway not in animals (so why we cant synthesize these amino acids) so target for weed killers

81
Q

Coumarins are potent

A

Toxic and shit

82
Q

Flavonoids:

A

plants use to protect from UV radiation (included anthocyanins and other pigments)

83
Q

Alkaloids are chemically heterogenous but all have

A

-are water soluble
-have at least one N
-exhibit strong bio activity

84
Q

Lignin

A

-highly cross-linked polymer of thee phenolic building blocks- random structure
-strong and difficult to degrade

85
Q

Alkaloids

A

-many mimic neurotransmitters have psychotropic effects
-many highly toxic
-most derived form amino acids
-classified according to their ring structures

86
Q

Some examples of alkaloids

A

caffeine, opioids, cocaine, nicotine

Plant Phys AA😩 (2 decks)

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