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Organisms 1 > Lecture 6 > Flashcards

Lecture 6 Flashcards

1
Q

Where are the light reactions happening in plants?

A

Chloroplast
Thylakoid membranes in particular

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2
Q

What is the granum?

A

Stacks of thylakoid

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3
Q

What does the granum do?

A

Split water
Formation of ATPA and NADPH

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4
Q

What is the lumen?

A

The inside of the thylokoid

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5
Q

What is the stroma?

A

What is outside of the thylakoid membrane

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6
Q

Where can we find more photosystem IIs

A

In the granum

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7
Q

Where can we find more ATP synthase?

A

In the stroma

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8
Q

Where is the energy lost during photosynthesis going?

A

Heat
Fluorescence
Light in another wavelength
Resonance energy transfer

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9
Q

What are photsystems?

A

Discrete units that carries 250-400 pigments which absorb light for photosynthesis

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10
Q

What is an antenna complex?

A

Where the light is captured

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11
Q

What is the reaction centre?

A

The centre where the reactions happen of a photosystem

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12
Q

Where are the pigment molecules?

A

Embedded in thylakoid and associated with protein

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13
Q

How does the reception of light in photosystems work?

A

There is loss of electron which the pigments get and pass to each other until they reach the special chlorophyll a pigment by resonance energy transfer.

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14
Q

What is a light-harvesting complex?

A

Photosystem/funnel without a reaction centre that surrounds each photosystems.

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15
Q

What is the photosystem complex?

A

Photosystems and light-harvesting complexes

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16
Q

How does the reaction centre work?

A

The chlorophyll a molecule absorbs energy
One electron is boosted to a higher level
The electron is transfered to an electron acceptor which initiates energy flow
(Oxidization of chlorophyll a and reduction of electron acceptor)

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17
Q

What are the two photosystems linked by?

A

Electron transport chain

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18
Q

What is the optimal wavelength for photosystem I?

A

700

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19
Q

What is the optimal wavelength for photosystem II?

A

680

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20
Q

Where is the photosystem I mostly located?

A

In the stroma and the periphery of the stacks of thylakoid

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21
Q

What is the first electron acceptor in photosystem 2?

A

Pheophytin

22
Q

What is PQa?

A

Plastoquinone tightly bound to the reaction centre that passes electron to the next unit

23
Q

What is PQb?

A

Plastoquinone which also picks up two protons from the stroma. It passes two electrons and two protons to Cyt b6/f cinplex

24
Q

What is PQb reduced to during the electron transport chain in photosystem 2?

A

Plastoquinol (PQbH2)

25
What is the order of the electron transport chain of photosystem 2?
P680 to phoephytin to PQa to PQb to Cyt b6/f complex
26
In the electron transport chain of photosystem 2, what part has the highest energy level?
P680 (it lessens as the electron goes down the chain)
27
What are the two parts of plastoquinone? Also, explain a bit.
Benzoquinone (which takes the electron) Isoprenyl (hydrophobic to be able to anchor to lipid bilayer)
28
What is pheophytin?
A modified chlorophyll a molecule where the magnesium is replaced by two protons.
29
How is the flow of the electrons through the system of photosystem 2?
Constant directional (non-cyclical)
30
What is water photolysis?
Water being split by photons
31
Where can we find the Mn4O5Ca cluster?
At the base of the photosystem facing the thylakoid lumen
32
How many photons are required to split two water molecules?
4
33
What is Mn4O5Ca?
Cluster (intricate network) of manganese, oxygen and calcium ions that strip electrons of of water and are embedded in the photosystem 2 protein complex
34
How does water oxidization in photosystem 2 work?
Water is split Two electrons are split and passed to the complex (will be used for NADPH) It replaces the electrons lost by P680
35
What is P 680
Reaction centre of photosystem 2. A chlorophyll a that absorbs light energy and excites electrons
36
What happens in the cytochrome b6/f complex?
2 electrons are donated (one at a time) 2 protons are funneled into the lumen 2nd way proton gradient is built The reduced cytochrome f donates electrons to plasticyanin
37
What is phylloquinone?
Similar to Plastoquinone (has O to take in electrons and big hydrophobic tail)
38
What is the primary electron acceptor in photosystem 1?
A0
39
How are electrons passed down in photosystem 1?
Downhill on the stromal, side of the membrane
40
What is NADP+ catalyzed by?
FNR
41
What happens in photosystem 1?
Reduction of NADP+ Oxidation of P700 Noncyclic photophosphorylation Sometimes cyclic photophosphorylation
42
How does cyclic photophosphorylation work and what does it give?
Electrons excited at photosystem 1 by P700 They pass through the cascade to the cytochrome complex to plastocyanin back to photosystem 1 Protons are pumped into the lumen It drives ATP synthesis It is necessary for carbon fixation and does a ration of 3 ATP to 2 NADPH
43
When does cyclic photophosphorylation happen?
When there is too much light
44
What is the order of the electron transport chain of photosystem 1?
P700 Modified chlorophyll a (A0) Phylloquinone Iron-sulfur protein Ferrodoxin
45
What is Ferrodoxin?
Mobile iron-sulfur protein
46
What happens when both photosystem 1 and 2 work simultaneously together?
Photosystem 2 supplies electrons continuously for photosystem 1 They need a balance of emergy at the reaction center It give 6 electrons per turn Produces 6 ATP and 6 NADPH Non-cyclic electron flow Noncyclic photophosphorylation
47
What is photophosphorylation?
Light dependent reactions that turn ADP to ATP
48
When are protons released into the thylakoid lumen by the ATP synthase complex?
During oxidation of water Via cytochrome b6/f complex
49
What does the fact that protons are released into the thylakoid lumen generate?
An electron proton gradient of the lumen and stroma
50
What happens in the ATP synthase complex?
Flow of protons through ATP synthase Potential energy gradient Chemiosmotic coupling
51
What is chemiosmotic coupling?
Osmosis coupled with chemical reactions

Organisms 1 (10 decks)

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