Topic 6 Flashcards

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1
Q

characteristics of chemolithotrophy?

A

only occurs in prokaryotes
evolved when organic molecules weren’t abundant

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2
Q

which primary electron donors does chemolithotrophy use?

A

H2S, Fe, H2, NH3

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3
Q

what does chemolithotrophy not require?

A

glycolysis
fermentation
bridge reaction
Krebs cycle

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4
Q

what does chemolithotrophy require?

A

ETC
oxidative phosphorylation

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5
Q

why aren’t all metabolic pathways equal?

A

using different primary electron donors or final electron acceptors generate a proton gradient in which can differ in strength
-organic electron acceptors hold more potential energy and generate greater PMF than inorganic
-oxygen is the strongest final electron acceptor and will generate a greater PMF

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6
Q

strength of PMF for aerobic respiration?

A

greatest PMF—> most ATP

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7
Q

strength of PMF for aerobic respiration?

A

less PMF—> less ATP

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8
Q

strength of PMF for chemolithotrophy?

A

least PMF—> least ATP

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9
Q

how do reduction reactions work?

A

-polar covalent bonds in the reactant are broken
-nonpolar covalent bonds in the products are formed
-bonding electrons between carbon and oxygen in CO2 have moved closer to the C atoms in glucose so CO2 is reduced
-bonding electrons between the oxygen and hydrogen in H2O have moved farther away from the O atoms in O2 so water is oxidized

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10
Q

what are membranes in the chloroplast?

A

outer
inner
thylakoid

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11
Q

what are the two spaces in the chloroplast?

A

stroma
lumen

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12
Q

what is the electromagnetic spectrum?

A

waves of different solar energy exist as photons and can be visible

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13
Q

which part of the electromagnetic spectrum is important in photosynthesis?

A

400-700

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14
Q

what happens when a photon hits an object?

A

it can be:
reflected (bounces back)
transmitted (pass through)
absorbed (electrons gain energy of the photon)

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15
Q

what is pigment?

A

molecules efficient at absorbing photons

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16
Q

how do pigments work?

A

their chemical structure allows their electrons to absorb solar energy and move to a higher level
-they absorb specific wave lengths which must match exactly the energy needed to raise an electron to a higher level

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17
Q

what do blue pigments do to electrons?

A

raise them 2 levels

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18
Q

what do green pigments do to electrons?

A

wont raise an electron

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19
Q

what do red pigments do to electrons?

A

raise them 1 level

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20
Q

where are photosynthetic pigments?

A

embedded in the thylakoid membrane

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21
Q

what are the main pigments for phototrophs?

A

chlorophylls

22
Q

what do chlorophylls do?

A

captures energy for photosynthesis

23
Q

what are carotenoids?

A

accessory pigments that extend the wavelength for energy absorption

24
Q

how are pigment molecules organized?

A

into photosystems which are light harvesting systems

25
Q

what is a reaction center?

A

a collection of proteins that interact with pigments

26
Q

what is clustered around reaction centers?

A

antenna pigments

27
Q

what do antenna pigments do?

A

channel energy to the reaction centre when excited

28
Q

how do reaction centres reduce a primary electron acceptor?

A

light is absorbed by an antenna pigment
-energy is transferred by inductive resonance to the reaction centre
-the reaction centre’s special chlorophyll donates an excited e- to the primary e- acceptor

29
Q

characteristics of a light dependent reaction?

A

solar energy is used to make ATP and NADH
linear electron transport

30
Q

what pigment does photosystem 2 use?

A

P680

31
Q

what pigment does photosystem 1 use?

A

P700

32
Q

how does photosystem 2 generate PMF

A

P680 reduces the primary e- acceptor which passes the e- to plastoquinone
-Pq reduces the cytochrome complex and release the H+ to the lumen
-cytochrome reduces Plastocyanin

33
Q

what is plastoquinone?

A

a hydrophobic electron taxi that grabs an electron from the stroma when reduced

34
Q

what is plastocyanin?

A

a hydrophilic electron taxi

35
Q

how does P680 replace its electron?

A

by oxidation of H2O

36
Q

How does photosystem 1 produce NADPH?

A

P700 reduces the primary electron acceptor which passes the electron to ferredoxin
-NADP+ reductase reduces NADP+ to NADPH in the stroma

37
Q

what is ferredoxin?

A

a hydrophilic electron taxi that reduces NADP+ reductase

38
Q

how does P700 replace its electron

A

by accepting electrons from plastocyanin

39
Q

what does electron flow through both photosystems produce?

A

a strong proton electrochemical gradient across the thylakoid membrane

40
Q

how is the strong proton electrochemical gradient formed?

A

H+ released in the lumen by oxidation of H2O
H+ pumped from stroma to lumen
H+ are used in the stroma to reduce NADP+

41
Q

what is photophosphorylation?

A

using solar energy to generate PMF to power ATP synthase for chemiosmosis

42
Q

where is ATP generated during photophosphorylation?

A

the stroma side of the thylakoid membrane

43
Q

what are the three steps of the Calvin cycle?

A

carboxylation/fixation
reduction
regeneration

44
Q

why do we need cyclic electron transport?

A

because the Calvin cycle needs more ATP than linear electron transfer makes

45
Q

what happens in cyclic electron transport?

A

ferredoxin reduces Pq instead of NADP+ reductase
electrons flow normally to P700 to generate PMF

46
Q

what is the product of photosynthesis?

A

G3P

47
Q

where is G3P formed?

A

calvin cycle

48
Q

what is G3P converted to?

A

glucose

49
Q

uses for G3P glucose?

A

used in glycolysis and aerobic respiration
linked into polymers of starch or cell walls
used in synthesis of macromolecules (amino acids, fatty acids, nucleic acids)

50
Q

characteristics of cyanobacteria?

A

responsible for oxygenation of earth
photosynthetic mechanicm similar to chloroplasts (ps1, ps2, calvin cycle)

51
Q

characteristics of anoxygenic photosynthesis?

A

only prokaryotes
before oxygen and organic molecules were abundant
first metabolism to use ETC
only uses cyclic electron flow
does not split H2O
does not produce oxygen