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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
If you observe conversion of etioplasts to chloroplasts, do you expect PIFs to induce or repress?
repress
26
If you observe seedling hypocotyl elongation, do you expect PIFs to induce or repress?
promote (branching repressed?)
27
What type of molecule is a PIF?
transcription factor
28
Blue light responses mediated by three different types of photoreceptor molecules:
1) Phytochromes 2) Cryptochromes 3) Phototropins
28
Phytochromes-
respond to red light (some responses mediated by blue light)
29
Cryptochromes-
Blue light (got flavin, involved with circadian rhythms) inhibition of hypocotyl elongation, flowering, cotyledon expansion
30
Phototropins-
phototropism, chloroplast movement
31
What type of molecule is phytochrome?
protein kinase
32
What light activates cryptochromes?
Blue light
33
inhibition of hypocotyl elongation controlled by who?
Cryptochromes
34
Who is phototropism primarily mediated by?
Phototropins
35
Phototropins have also
flavin chromophores that sense light, cause conformational change in protein, auto phosphorylation
36
Activated phototropins cause the hormone ______ to
auxin to accumulate on shady side of stem, resulting in positive phototropism
37
Auxin causes cell elongation which bends
the plant (towards light source)
38
Phototropins also mediate chloroplast movement in response to
light
39
in the absence of drought, stomata respond primarily to
ambient light
40
For stomatal opening, who drives K+ into the cell?
H+ATPase pumps protons out creating charge gradient, so potassium ions are drawn into guard cells
41
How does auxin accumulate on the shady side of a stem?
by phosphorylating/ deactivating auxin transporters (ABC proteins) on the sunny side of the stem
42
What are the five traditional classes of plant hormones:
-auxins -cytokinins -ethylene -abscisic acid -gibberellins
43
Where are auxins produced and how do they move?
produced in shoot apex and leaves, moves down but not up the plant (basipetal movement)
44
-auxin accumulates at bottom side of lateral shoot or root.
45
Do plant hormones react locally or over long distances in the plant?
Both
46
What is the general auxin structure?
indole ring and acetic acid side chain
47
Effect of auxin on cell frowth exactly opposite in shoots bc roots.
In roots, auxin inhibits elongation of cells (drift due to starch?)
48
PIN proteins transport to allow auxins to
flow from one cell to another, down and through
49
Positive root geotropism,
moves toward gravity, auxins inhibit cell growth
50
Auxin also involved with apical domaince
branching and shoots at shoot apex (if cut off tip)
51
auxin helps form vascular strands
to new leaf primordia or in damaged stems (also stimulates differentiation into vascular cambium)
52
If seeds removed, fruit wont develop. Addition of what hormone to fruit allows for seedless varieties?
auxin
53
Cytokinins general structure
adenine base (very nitrogenous)
54
the auxin:cytokinin ratio regulates morphogenesis
high auxin: roots Intermediate: callus Mid: shoots
55
Plant cells stem cells can go back?
Yes
56
Cytokinins also inhibit leaf
senescence could be bad if not use bc prep for winter or something
57
ethylene plays a major role in
fruit ripening, leaf abscission (leaf fall off), and inhibition of cell expansion (not class of hormones, one molecule)
58
Main roles of abscisic acid
1) suppression of seed germination 2) stomatal closure
59
main roles of gibberellins
longitudinal growth and breaking seed dormancy
60
ethylene fruit ripening what happen
breakdown of chlorophyll, becomes starch
61
ethylene and auxin are what qith respect to leaf abscission?
antagonistic (ethylene promotes it)
62
Maize mutant insensitive to ABA (absicisc acid) what happens
seeds grow while still on plant and not ripened or dispersed
63
Some seeds (red mangrove plant) seeds germinate while still in the fruit, why?
they do this bc frequently flooded, so they can drop right into mud
64
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
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
Dwarf plant phenotypes can be rescuded by addition of what hormone?
gibberellins
66
Gibberellins are what to ABA?
Antagonistic
67
What are "secondary compounds" basically defined as?
Not involved in growth and development, often used for defense
68
Terpenes structure what, and hydrophobicity/hydrophilicity
molecules built from isopentyl diphosphate IPP generally hydrophobic from all the C-H bonds
69
Terpenes use what two synthesis pathways in plants?
mevalonic acid pathway and MEP pathway
70
For Mevalonic acid pathway-
-The 5 carbon backbone of IPP is build up from acetyl CoA (come straight from cellular respiration)
71
For the MEP pathway for biosynthesis, uses who for carbon from what cycle
G3P from the C3 cycle which is joined to pyruvate form glycolysis precursors of IPP
72
Do terpenes have rings?
hell yeah brother
73
Describe terpenes vs terpenoids
terpenes only hydrocarbons terpenoids have oxygens in them
74
Terpenes include
hormones carotenoids pigments and essential oils -serve anti-herbivory functions -often aromatic hence smell -usually volatile
75
Glycosides consist of
sugar bound to something else, many feature glucose linked to terpenoid (have saponins, amphipathic)
76
What are phytoecdysones?
insect compounds that induce herbivore molting
77
Some terpenes can be polymers
such as rubber
78
Keep in mind there are many types of glycosides
Many discourage herbivory or happen to be toxic to us
79
Phenolics structure-
aromatic rings with hydroxyl groups
80
Shikimic acid pathway
starts with PEP, pathway not in animals (so why we cant synthesize these amino acids) so target for weed killers
81
Coumarins are potent
Toxic and shit
82
Flavonoids:
plants use to protect from UV radiation (included anthocyanins and other pigments)
83
Alkaloids are chemically heterogenous but all have
-are water soluble -have at least one N -exhibit strong bio activity
84
Lignin
-highly cross-linked polymer of thee phenolic building blocks- random structure -strong and difficult to degrade
85
Alkaloids
-many mimic neurotransmitters have psychotropic effects -many highly toxic -most derived form amino acids -classified according to their ring structures
86
Some examples of alkaloids
caffeine, opioids, cocaine, nicotine

Plant Phys AA😩 (2 decks)

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