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Biochem > Lecture 23 Photosynthesis > Flashcards

Lecture 23 Photosynthesis Flashcards

(73 cards)

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1
Q

what does the term heterotrophic organisms mean

A

they require other things to make carbon and nitrogen compound for us

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2
Q

what do photosynthetic cells do?

A

use CO2 and H2O to make carbs and oxygen

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3
Q

what are the two types of reactions in photosynthesis

A

Light reactions and dark reactions

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4
Q

what do the light and dark reactions each do generally

A

Light dependant- absorb photons to power the synthesis of ATP and NADPH

dark rxns- Use ATP and NADH to run the pentose phosphate and glycolysis in reverse

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5
Q

what part of the plant is responsible for the green pigment

A

Chloroplasts

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6
Q

how many chloroplasts per cell

A

20-50

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7
Q

what are inside chloroplasts

A

thylakoids

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8
Q

where does photosynthesis take place

A

in the thylakoid membrane

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9
Q

stroma vs lumen

A

stroma is the space outside of the thylakoids but still in the chloroplast
lumen in the space inside the pancake (thylakoid)

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10
Q

Per eukaryotic cell how many mitochondria do you typically have?

A

10

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11
Q

what does UV light do

A

breaks CC bonds

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12
Q

what does infrared light do

A

bond rotation and vibration, producing heat

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13
Q

Practice calculations with energy of photon given a wavelength

A

practive

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14
Q

At what wavelengths of light are best for growth

A

400 (blue)
650 (red)

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15
Q

what is the action spectra

A

the chart showing at what visible light wavelengths plant grow best

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16
Q

what does the structure of chlorophyll look like

A
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17
Q

what part of the structure of chlorophyll does light come into contact with

A

the heme like propphin ring

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18
Q

what does the heme like prophin ring act like in chlorophyll?

A

like an effective antenna

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19
Q

why does chloroplast have a long nonpolar chain

A

so it can be embedded in the thylakoid membrane

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20
Q

what are carotenoids

A

accessory pigments that are more orange yellow and red (ie REFLECT all those colors)

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21
Q

what are two examples of carotenoids

A

Beta- Carotene and Lutein (xanthophyll)

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22
Q

what pigment degrades the fastest

A

green (chlorophyll)

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23
Q

Why are conjugated pi clouds important for light absorption in plants

A

Conjugated π clouds (alternating single and double bonds) delocalized electrons across multiple atoms.

This lowers the energy gap between molecular orbitals.

Smaller energy gaps allow pigments to absorb visible light (rather than just UV).

The wavelengths absorbed determine the color reflected.

Examples:

Chlorophyll (green) – absorbs red and blue

Carotenoids (orange/yellow) – absorb blue/violet

Key idea: Conjugation enables color by shifting light absorption into the visible range.

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24
Q

the more bigger the pi system the more the plant absorbs shorter or longer wavelengths of light

A

longer

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25
what are the roles the accessory pigments play in photosynthesis and where are they present
they are considered "antenna molecules" they are embedded into the thylakoid membrane, where they get an excited electron if they receive light and then exited the antenna next to it until they reach the reaction center.
26
what is the privileged chlorophyll also called
the reaction center
27
what are the three layers of the reaction venter
Top to bottom Electron acceptor Privileged chlorophyll Electron donor
28
what do each of the components of the reaction center do
Electron acceptor: Immediately receives the excited electron from the chlorophyll. Privileged chlorophyll : Absorb light energy and donate an excited electron Electron donor: Replaces the electron lost by the special chlorophyll to keep the cycle going.
29
what is the electron acceptor that accepts e- from photosystem 1
ferredoxin
30
what is ferredoxin
the electron acceptor in PS1 the light havestin reaction
31
where is the privileged chlorophyll located
in the middle of photosystem 1
32
what is the electron donor that gives e- back to photosystem 1
Plastocyanin
33
what is plastocyanin
the electron donor that gives e- back to photosystem 1
34
to what side of the membrane does the privileged chlorophyll direct its e- transfer towards
the stroma side
35
what is the N side
Stroma (bc that's where all of the electrons are going dear)
36
What is the P side
the lumen side
37
is plastocyanin on the P or N side
P side (its job is to give e- back to queen b)
38
is ferredoxin on the P or N side
on the N side bc ts the e- acceptor
39
how many protons can be pumped per photon of light
2
40
another name for PS1 and why is it called that
P700- bc that is the most efficient wavelength for photosystem 1
41
what is the best wavelength for photosystem 1
700nm
42
In PS1 after the electron is transferred to ferredoxin, where does it go next
Cytochrome b6 F (which them pumps 2 protons per photon)
43
what is the purpose of cytochrome b6 f
to pump protons into the lumen to generate a gradient for ATP synthase
44
where does cytochrome b6f dump give its electrons two in the PS1 rxn after its done pumping protons into the lumen, and what does this make it?
back to plastocyanin! which makes it cyclic flow!!
45
what does the cyclic flow of PS1 only purpose
to make ATP (IE by continuously making a proton gradient)
46
What are the inputs and outputs of cyclic flow
In: ight (photons) and existing electrons out: ATP cyclic flow can only pump protons to make ATP
47
what electron carrier does cytochrome b6f use
plastoquinone
48
what is cytochrome b6f homologous to in the mitochondria
ETC complex 2
49
pathway of cyclic flow
exited e at privileged chlorophyll ---> transferred to ferredoxin ---> electrons transferred to plastoquinone---> PQH2 goes to the cytochrome B6 f complex ----> complex pumps 2 protons into the lumen and then gives electron to plastocyanin ---> plastocyanin gives electron back to PS1 so it can be ready to be re exited
50
Pathway of noncyclic flow in PS1
exited e at privileged chlorophyll ---> transferred to ferredoxin ---> make NADPH
51
does cyclic or noncyclic flow happen when photosynthesis is up and running?
non cyclic
52
issue with non cyclic flow, how do we solve that?
you don't refill the privileged chlorophyll, PS2
53
What does PS2 produce
oxegen!!
54
what is the ideal wavelength for PS2
680
55
PS2 other names
water splitting complex or oxygen generating complex
56
How does ps2 make oxegen
manganese middle ions coordinate 2 water molecules so that it can tease 1 proton and 1 e- out per excitation (per photon). the 4 protons released on the P sise (lumen) to contribute to the concentration gradient
57
balance sheet for PS2 initial water splitting
2H2O + 4 photons ----> 4H+ + 4e- + O2
58
which side is ATP being generated on
stroma side (opposite to mito)
59
what happens in PS2 after water splitting step
e- from water splitting goes into P680 (privileged chlorophyll of PS2) ---->then move them into cytochrome B6f complex (like in PS1) which then goes into proton gradient and e- are moved into plastocyanin ---> plastocyanin regenerates P700 of PS1
60
in mitochondria what side is ATP pumped on
Matrix
61
how many protons are pumped into the lumen per formation of O2
12 (4 from splitting + 8 from cytochrome b6f ( 2 H + per e-, 1 e- per photon and you have 4 photons) )
62
how many protons per ATP
4
63
what is the Z scheme
the non cyclic flow of both PS1+PS2
64
idea of Z scheme
4 photons into PS2 ---> 4 Photons into PS1 ---> 12 H+ pumped
65
formula for z scheme
8 Photons + 2NADP+ + 3ADP +3HPO4^-2 +H+ ---> O2 + 3ATP + 2NADPH + H2O
66
what are the light reactions
PS1 and PS2
67
do the dark reactions only happen in the dark?
no they are just "independent of light"
68
What is another work for dark rxn
calvin cycle
69
what does the Calvin cycle do
uses the NADPH and ATP generated from light RXNs to take Co2 and generate Carbohydrates
70
where do the dark RXNs take place
chloroplast stroma compartment
71
what is rubisco? how many monomers does it have?
its an octamer! is the enzyme that fixes CO2 but its slow so theres a loooooot of it
72
iis Rubisco cooperative
yes! it's an octomer so its subject to a lot of regulation
73
FIGURE OUT RUBISCO MECHANISM

Biochem (7 decks)

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