Cellular Respiration/Photosynthesis Flashcards
1
Q
How is food converted to ATP?
A
A series of catabolic and anabolic reactions
2
Q
What is cellular respiration?
A
Collection of metabolic reactions within cells that breaks down food molecules and uses the liberated free energy to synthesize ATP
3
Q
What are the types of cellular respiration? Differences?
A
Aerobic respiration- oxygen is final electron acceptor
Anaerobic respiration- molecule other than oxygen is final electron acceptor
Fermentation- no ETC
4
Q
What are redox reactions?
A
Involve a transfer of electrons between molecules
5
Q
What is oxidation vs reduction?
A
Oxidation loses electron
Reduction is gainjng
6
Q
What is the oxidizing agent vs reducing agent?
A
Oxidizing agent accepts the electron (reduced)
Reducing agent donates the electron (oxidized)
7
Q
What do electrons travel with? This means?
A
Protons
Adding or removing hydrogen is associated with redox reactions
8
Q
What are electron carriers? Examples in cellular respiration?
A
Molecules that accept molecules from the breakdown of glucose
NAD+—>NADH
FAD—>FADH2
9
Q
Where does cellular respiration occur?
A
The mitochondria
10
Q
What are the steps of cellular respiration?
A
- Glycolysis
- Pyruvate oxidation
- Kreb’s/Citric acid cycle
- Electron transport chain
- Chemiosmosis
11
Q
What are the ways ATP is made in cellular respiration? What is the difference?
A
Substrate level phosphorylation
- enzyme catalyzes transfer of phosphate from high energy substrate to ADP
Oxidative phosphorylation
- ATP is created with ADP and inorganic phosphate by enzyme ATP synthase
- links oxidation of NADH +FADH2 with the phosphorylation of ATP
12
Q
Why is cellular respiration stepwise?
A
Allows more energy to be useful and stored by electron carriers instead of being released as heat
13
Q
What is the overall vs net production of ATP in glycolysis?
A
Overall 4
Net 2
14
Q
What is the point of glycolysis?
A
Split glide into two 3 carbon molecules called pyruvate
15
Q
What is the first step of glycolysis? What is the purpose?
A
Glucose is phosphorylated
makes it more reactive
16
Q
What do kinases do?
A
Play role in removing phosphate from ATP
turning ATP to ADP
17
Q
What happens after glucose is phosphorylated in glycolysis?
A
Glucose 6-phosphate is rearranged into fructose 6-phosphate
18
Q
What do isomerases do?
A
Rearrange molecules without removing anything
19
Q
What happens after glucose is rearranged into fructose? What is purpose?
A
It is phosphorylated again to make fructose 1,6-biphosphate
Makes it so reactive it has to continue to the next step
20
Q
What is the rate limiting step in glycolysis? Why?
A
Phosphorylating fructose 6-phosphate into fructose 1,6-biphosphate because the reaction can’t proceed without it and you can’t undo this step
21
Q
What is phosphofructokinase?
A
Catalyzes removal of phosphate from atp and making fructose 1,6-biphosphate
22
Q
What happens after fructose 1,6-biphosphate is created in glycolysis?
A
It splits and turns into 1 G3P and 1 DHAP which is then converted to G3P with isomerase
23
Q
How many G3P are produced by one glucose molecule?
A
2 G3P
24
Q
When is DHAP converted to G3P?
A
When we need more energy
25
What is the difference in function between mutase and isomerase?
Nothing
Same function
26
What happens after 2 G3P are produced in glycolysis?
Rearranged to make one 2-phosphoglycerate per G3P
27
What happens after 2-phosphoglycerate is produced in glycolysis?
One water is removed per molecule and it is turned into a PEP molecule
28
What happens after PEP molecule is produced?
One ATP is produced per PEP molecule and it produced pyruvate
29
How is ATP produced during glycolysis?
Substrate level phosphorylation
30
Is carbon lost is glycolysis?
No
31
What is the net production of glycolysis?
2 pyruvate
2 NADH and 2 H+
2 ATP
32
Where does glycolysis take place?
Cytoplasm
33
What happens after glycolysis is in aerobic conditions?
Pyruvate oxidation
34
Why is pyruvate oxidation important?
Transitions between glycolysis and the citric acid cycle
35
What is the production of pyruvate oxidation per pyruvate? What about total?
1 acetyl-CoA, 1 NADH, 1 CO2 per pyruvate
2 acetyl CoA, 2 NADH, 2CO2
36
Where does pyruvate oxidation take place?
Mitochondrial matrix
37
What is produced per acetyl-CoA? (Per turn)
1 ATP
3 NADH
1 FADH2
2 CO2
38
What is the first step of the kreb’s cycle?
The two carbon acetyl CoA is added to the four carbon oxaloacetate to create the 6 carbon citrate
39
Why is CoA released only to be added back later?
Allows oxaloacetate to join and form citrate by releasing energy
40
What happens after citrate is produced in the citric acid cycle? What is the enzyme used?
Citrate is rearranged into isocitrate (no carbon lost)
Isomerase
41
What happens after isocitrate is produced in the Kreb’s cycle
Dehydrogenase enzyme removes hydrogens and adds them to NAD+ to create NADH
One carbon is released as CO2
Forms alpha-ketoglutarate
42
What happens after alpha ketoglutarate is produced in the kreb’s cycle?
Another dehydrogenase reduces NAD+ to NADH
another carbon is lost as co2
CoA-SH removed from acetyl CoA is added
43
What happens after succinyl CoA is produced in the Kreb’s cycle
CoA is released
Phosphate is added which turns GDP to GTP and then phosphate is given from GTP to ADP to make 1 ATP
Produces succinate
44
What happens after succinate is produced in the Kreb’s cycle?
Succinate dehydrogenase removes 2 e- and 2 H+ which are used to reduce FAD to FADH2
Produces fumarate
45
What happens after funerals is produced in the Kreb’s cycle?
Water is added and bonds are rearranged
Produces malate
46
What happens after malate is produced in the Kreb’s cycle?
2e- and 2H+ and used to reduce NAD+ to NADH
Oxaloacetate is recreated
47
Why is it necessary that we produce oxaloacetate as the last step of the citric acid cycle?
Because it’s a reactant in the first step
Cycle
48
Why is CO2 produced in the Kreb's cycle?
because in order to continue the cycle we need to remake oxaloacetate which has 4 carbons
49
Where is the energy released by cellular respiration stored?
NADH FADH2 ATP
50
What is the purpose of the electron transport chain? Does it produce ATP?
create a proton gradient
no
51
What is the electron transport chain?
a series of integral membrane proteins that are located in the inner membrane of a mitochondria
involved in transferring protons from the matrix to the intermembrane space
52
What is the intermembrane space>
space between the inner and outer membrane of the mitochondria
53
What is the role of ubiquinone and cytochrome c is the ETC?
transport electrons between the complexes
54
What is the final electron acceptor in the ETC? What happens if missing?
oxygen
process stops
55
What complexes does ubiquinone transport between? What about cytochrome c?
takes electrons from complex 1 and 2 and transports them to complex 3
takes electrons from complex 3 and brings them to complex 4
56
What is the proton gradient created by the ETC used for?
chemiosmosis (ATP production)
57
What is proton motive force?
potential energy due to the concentration gradient (pH) of protons and the charge gradient (voltage) across the membrane
58
What is chemiosmosis?
harnessing the energy
present in the proton gradient to drive
chemical reactions (ATP production)
59
How is ATP made during chemiosmosis?
oxidative phosphorylation
60
What are the parts of ATP synthase?
Stator, rotor, catalytic knob
61
How does ATP synthase work?
H+ protons enter the stator and attach to the binding site of the rotor, this causes a conformational change
this shape change causes the rotor to spin
this spinning activates the catalytic sites in the knob which catalyzes the production of ATP
62
What factors affect proton motive force?
1. gradient being used for other work (Transport NADH and pyruvate)
2. H+ flows back into the matrix
3. ETC inhibitors
63
Is glucose the only molecule that can feed into the processes of cellular respiration?
no
proteins and fats can also
be broken down and brought
in at different parts of the
cellular respiration process
64
What is ATP an allosteric inhibitor and a substrate for?
phosphofructokinase
65
What inhibits phosphofructokinase? Why is it important?
ATP and citrate
excess energy is not produced
66
What is fermentation? What are the types?
anaerobic pathway, happens after glycolysis when pyruvate oxidation cannot occur
Ethanol and lactic acid
67
What is alcohol (ethanol) fermentation? Where does this occur?
after glycolysis, pyruvate is converted to ethanol, creates 2 ATP per glucose molecule
occurs in bacteria and yeast
68
What is photosynthesis?
conversion of light energy into chemical energy
69
What is oxidized and what is reduced in photosynthesis?
water is oxidized and co2 is reduced
70
Where will you find pyruvate, ETC, Kreb's cycle, proton gradient, and ATP synthase?
matrix
inner membrane
matrix
intermembrane space
inner membrane
71
What are the two stages of photosynthesis?
light-dependent reaction, light-independent reactions
72
Where does the light-dependent reaction and light-independent reactions occur?
chloroplast thylakoids
stroma
73
Is the colour we see the light we absorbed?
no, it is the light reflected
74
Does every pigment absorb every pigment at the same efficiency?
Different pigments absorb different wavelengths optimally
75
What are the photosynthetic pigments? What colours do they not absorb?
Chlorophyll a: does not absorb green
Chlorophyll b: does not absorb green
Carotenoid: does not absorb yellow-orange
76
What is the difference between the action vs absorption spectrum?
action shows rate of photosynthesis at different wavelengths of light including all pigments
absorption shows the absorption rate of a pigment at different wavelengths
77
Why the wavelength absorption vary between pigments?
structure of pigments
78
What is ground state?
lowest (normal) energy state of an atom (electron)
79
What happens when a photon is absorbed?
electron gets excited and jumps from ground state to a higher energy orbital but they eventually return to ground state
80
What three pathways can occur after an electron is excited?
1. They return to ground state without energy transfer. The energy
is released as a low-energy photon or heat
2. The energy is transferred to another pigment before returning to
ground state
3. A high energy electron is transferred to an electron acceptor
81
What is the difference between photosystems I and II?
photosystem I: chlorophyll a in reaction centre is called P700, absorption maximum is 700nm
photosystem II: chlorophyll a in reaction centre is called P680, absorption maximum is 680nm
82
What does a photosystem consist of?
large antenna complex of pigments that surrounds a central reaction centre
83
What happens when a photon hits a photosystem?
photon is absorbed by pigment in the antenna complex
energy is transferred to a pair of chlorophyll a, and then to the primary electron acceptor called pheophytin in the reaction centre
electron is then transferred to the ETC
84
Which pigments are found in the antenna complex?
chlorophyll b and carotenoids
85
How are the electrons released from chlorophyll a replaced?
splitting two water molecules, what releases O2
86
Where does the splitting of water occur in photosynthesis?
photosystem II
87
What is the electron carrier in photosynthesis?
NADP+ which is reduced to NADPH
88
Where is the ETC located in chloroplasts?
thylakoid membrane
89
What would happen if NADPH was low?
ETC would slow down or stop
90
What does plastoquinone do?
helps move electrons along the thylakoid membrane
91
What happens in photosynthesis as electrons are passed along? What prevents this?
they lose energy
photons are absorped which excites the electrons
92
What is the final electron acceptor in the light dependent reactions?
NADP+
93
Is ATP stored? Why or why not?
no
unstable
94
How can lipids and proteins be used in cellular respiration?
Lipids: fatty acids are converted into acetyl CoA and glycerol can enter glycolysis
Protein: amino groups are removed and the remaining carbon compound is converted to pyruvate, acetyl CoA, etc
95
Approximately how many ATP is produced per NADH and FADH2?
NADH makes 3 and FADH2 makes 2
96
What are the yields of aerobic, anaerobic, and fermentation ordered from higher to lowest?
aerobic>anaerobic>fermentation
97
What are the similarities and differences of fermentation and anaerobic respiration?
similarities:
both don't require oxygen and both produce ATP
differences:
nearly every organism can perform fermentation but only certain prokaryotes perform anaerobic, in anaerobic glucose is turned into CO2 and in fermentation glucose is turned into an organic molecule, anaerobic also makes more ATP
98
What is photophosphorylation?
use of light energy in order to generate ATP
99
Why are electrons not directly transported to NADP+?
2 photons are required to overcome the energy difference between NADPH and H2O
100
What is linear electron transport?
electrons are transferred from water to NADP via the electron transport chain to produce one NADPH and one ATp
101
What is cyclic electron transport?
moves protons across the thylakoid membrane without the involvement of photosystem II
energy absorbed from light is converted into ATP without reducing NADP+
102
What are the light independent reactions?
Calvin cycle, doesn't require light
103
What is needed to make one glucose?
2 G3P, 6 Co2, 18 ATP, 12 NADPH
104
How many CO2 enter the calvin cycle at a time?
1
105
What are the 3 stages of the calvin cycle? What happens?
carbon fixation: RuBP joins w/CO2 with help from Rubisco to form 3PGA
reduction: uses 6 ATP and 6 NADPH to make G3P
regeneration: one g3p leaves the cell and the others are used to regenerate RuBP (requires ATP)
106
How many turns of the calvin cycle does it take to make 1 G3P? Glucose?
3
6
107
What is the difference between oxygenic and a anoxygenic photosynthesis?
Oxygenic produces oxygen as a waste product because water is split to give electrons to photosystem and released as waste
108
What does ferrodoxin do?
Reduced by electrons from PSI and can transfer electrons to enzyme that catalyzes formation of NADPH
109
Where do the electrons from photosystem II and I do?
PSII: make proton gradient
PSI: make NADPH
110
What does plastocyanin do?
Takes electrons from cytochrome complex and donates them to reaction center in photosystem I
