Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

BIO1332 - Biochemistry > Photosynthesis > Flashcards

Photosynthesis Flashcards

1
Q

What is photosynthesis?

A

All free energy utilized by biological systems arises from solar energy that is trapped by the process of photosynthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

BASIC EQUATION for photosynthesis?

A

CO2 + H2O → (CH2O) + O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where does photosynthis take place?

A

In the chloroplast

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where does oxidative phosphorylation?

A

In mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the thylakoid membrane consisted to be analogous to?

A

The mitochondrial cristae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Give an overview of photosynthesis:

A
  • Light photon is absorbed
  • Energy used to drive an electron from water to generate NADPH
  • Also drives protons across a membrane
  • These protons drive ATP synthesis.
  • The ATP and NADPH are used in the light independent reactions (Calvin cycle) to fix CO2.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How is light energy trapped?

A
  • Photoreceptor molecule – chlorophyll a

- Four nitrogen atoms co-ordinate a magnesium ion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is light absorbed by in photosynthesis?

A

chlorophyll

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens when light is absorbed?

A
  • Chlorophylls have strong absorption bands in the visible region of the spectrum
  • Energy from light excites an electron from ground state to an excited energy level
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens after light is absorbed?

A

Electron is transferred to an acceptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is photosynthetic unit?

A
  • Large number of chlorophyll

- 2 types of chlorophyll

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the two types of chlorophyll?

A
  • 300 antenna chlorophylls (harvest light and transfer excitation energy to)
  • Reaction centre chlorophyll (undergo photochemistry)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Under normal conditions the reaction centre turns over how many times per second?

A

100

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does antenna chlorophyll do to the reaction centre?

A

Increase capacity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens once light is funnelled to the reaction centre chlorophyll?

A
  • Excitation electron can move to the acceptor molecule

- Positive charge on donor molecule and negative charge on acceptor molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is photo induced charge separation?

A

Formation of a +ve charge on the donor molecule and a -ve charge on the acceptor molecule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the sites where separation occur in photosynthesis?

A

Special pair of chlorophylls in the reaction centre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How is the photosynthetic apparatus arranged?

A

To make photo induced charge separation extremely efficient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the two types of membrane bound light-sensitive complexes in photosynthesis in green plants?

A 
Photosystem I (PS I) P700
Photosystem II (PS II) P680
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What wavelength of light does PS I respond to?

21
Q

What wavelength of light does PS II respond to?

22
Q

What do photosystems generate?

A

A proton gradient

23
Q

What is a proton gradient?

A
  • Electron flow
  • Electron are derived from H20 and reduces NADP+
  • Electrons first flow through PS II, then cytochrome bf then to PSI
24
Q

What is cytochrome bf?

A

a complex homologous to mitochondrial complex III

25
What is the overall result from photosynthetic electron transport?
2H2O + 2NADP+ + 8 hv  2H+ + O2 + 2NADPH
26
How many photons need to be absorbed to make 2 NADPH molecules?
8
27
What is the proton gradient across the thyklakoid membrane linked to?
ATP synthesis
28
What experiment idd Jagendorf do in 1966?
- Thylakoid membranes were soaked in pH 4 buffer for several hours. - Then rapidly submerged in pH 8 buffer containing ADP and Pi. - The pH inside the thylakoids initially remained at pH 4. - A burst of ATP production was noted that accompanied by the loss of the pH gradient.
29
What does ATP synthase resemble?
Those in mitochondria
30
What is ATP synthase?
- ATP synthase – CF1-CF0 complex - Orientation is reversed - Protons flow out of the thylakoid lumen - Protons flow into the mitochondrial matrix - Both ATP and NADPH are released into the stromal space ready for dark reactions (CO2 → carbohydrate)
31
What drives ATP synthesis?
The proton gradient across the Thylakoid membrane
32
Where does the Calvin cycle occur?
Chloroplast stroma
33
What does the Calvin cycle uses from the light reactions to fix CO2?
Products: | ATP and NADPH
34
How many NADPH and ATP does theCalvin cycle need per CO2 fixed?
2 NADPH | 3 ATP
35
What does the net product of 1 G3P require?
9 ATP | 6 NADPH
36
What are the three components of CO2?
- Fixation - Reduction - Regeneration
37
What is CO2 fixed by?
Enzyme rubisco
38
What happens when CO2, ribulose bisphosphate and enzyme rubisco react?
Produces two molecules of | 3-phosphoglycerat
39
What is 3-phosphoglycerate phosphorylated to by ATP?
1,3 bisphosphoglycerate
40
What is 1,3 bisphosphoglycerate reduced by to make glyceraldehyde-3-phosphate (G-3-P)?
By NADPH
41
What is glyceraldehyde-3-phosphate (G-3-P) used to regenerate?
Ribulose bisphosphate
42
What is Ribulose Bisphosphate Carboxylase Oxygenase?
- One of the most abundant proteins in the world | - Produces 2 molecules of phosphoglycerate from ribulose bisphosphate and CO2
43
what is regulation of CO2 fixation?
- Calvin cycle does not occur in dark - Key enzymes regulated - Enzymes found in chloroplast stroma
44
Why does the Calvin cyclin not occur in the dark?
Necessary ATP and NADPH would come from metabolising stored carbohydrates. This would be futile cycling.
45
What are the key enzymes which are regulated in the Calvin cycle?
- Rubisco - Fructose 1,6 bisphosphatase (FBPase) - Sedoheptulose 1,7 bisphosphatase (SBPase)
46
How are Rubisco, SBPase and FBPase controlled?
- Active in light - Inactive in dark - pH optima = 8 - Mg2+ activated enzymes
47
How does the increase in light activated the following enzymes Rubisco, SBPase and FBPase activity?
- Light - H+ are pumped from the storm to the thylakoids causing stroll pH to rise to 8 - Mg2+ increases concentration in stromal - Activating enzymes
48
How else are SBPase and FBPaseother than light regulated in the Calvin cycle?
Disulphide bridge to thiol transitions | -E- for reducing thioreedoxin are supplied by PSI via feerdoxin
49
What is CO2 captured by?
Rubisco

BIO1332 - Biochemistry (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions