1
Q
why is ATP hydrolysed?
A
to release energy needed for biological processes
2
Q
in which molecules is energy stored in
A
fats, carbs, lipids and proteins
3
Q
which biological processes require energy
A
- active transport
- cell division
- DNA replication
- endo/exocytosis
4
Q
define metabolism
A
all the chemical reactions happening within living cells
5
Q
what are anabolic reactions
A
synthesis of larger molecules from smaller ones which requires energy
6
Q
what are catabolic reactions
A
hydrolysis of large molecules into smaller ones which releases energy
7
Q
components in ATP
A
- ribose (5C sugar)
- adenine base
- 3 phosphate groups
8
Q
bond between ribose sugar and first phosphate group
A
phosphodiester
9
Q
what’s energy released during hydrolysis of ATP used for
A
- thermal energy/heat which helps maintain body temperature (enzymes can work at optimum temp)
- chemical potential energy in ATP which allows cells to do work
10
Q
where is the energy for the condensation reaction of ADP+Pi to ATP acquired from
A
energy released from respiration
11
Q
why is only a small amount of energy released when ATP is hydrolysed
A
- not wasteful
- prevents damage
12
Q
what are the 4 stages in respiration
A
- glycolysis (anaerobic process in cytoplasm)
- link reaction (in matrix)
- Krebs cycle (in matrix)
- oxidative phosphorylation
13
Q
what’s glycolysis
A
metabolic pathway that converts glucose to pyruvate
14
Q
outline glycolysis the steps in glycolysis
A
- phosphorylation of glucose (6C) to hexose bisphosphate (6C), 2ATP used for this
- splitting of of hexose bisphosphate (6C) into 2 triose phosphate molecules (3C)
- oxidation of the 2 triose phosphate molecules (3C) into 2 pyruvate molecules (3C), 2NAD reduced to 2 NADH and 4 ADP phosphorylated to 4ATP ( substrate level phosphorylation)
15
Q
products of glycolysis (for each glucose molecule)
A
- 2ATP (4 made, 2 used to start the process)
- 2 NADH
- 2 pyruvate molecules
16
Q
what occurs to the 2 pyruvate molecules made in glycolysis
A
they’re actively transported into the mitochondrial matrix for the link reaction
17
Q
role of NADH
A
carries H+ and e- to the cristae and delivers them to be used in oxidative phosphorylation for the generation of ATP
18
Q
what’s the link reaction
A
metabolic pathway that converts pyruvate (3C) into acetylcoA (2C)
19
Q
outline the steps in the Link reaction
A
- pyruvate (3C) is decarboxylated (releasing CO2) and dehydrogenated (producing NADH). This produces acetate (2C)
- coenzyme A (coA) is added to acetate (2C) producing acetylcoA (2C), which carries acetyl group to the Krebs cycle
20
Q
how many turns of link reaction per glucose molecule
A
2 as one pyruvate of the 2 produced in glycolysis is used
21
Q
which stages of respiration happen under aerobic conditions
A
- the link reaction
- the Krebs cycle
- oxidative phosphorylation
22
Q
what’s the cristae
A
inner highly folded mitochondrial matrix
23
Q
what’s the mitochondrial matrix
A
fluid filled inner part of the mitochondria
24
Q
shape of mitochondria
A
rod-shaped, thread like or spherical
25
what's the mitochondrial envelope made of
inner and outer phospholipid membrane
26
features of the inner membrane
- proteins that transport e- and **protein channels associated with ATP synthase** (allow H+ to diffuse through them) embedded in inner membrane
27
what's the space called between the inner and outer membrane
intermembrane space
28
what things does the mitochondrial matrix contain
- mitochondrial ribosomes where proteins are assembled
- looped mitochondrial DNA which may encode for enzymes and other proteins
- enzymes for link reaction and Krebs cycle
29
what's substrate- level phosphorylation
- direct transfer of a phosphate group from one molecule to another
- leads to the production of ATP from ADP+Pi during **glycolysis** and **the Krebs cycle**
30
what's the Krebs cycle ?
series of enzyme catalysed reactions that oxidise the acetate from the link reaction to 2 CO2, while conserving energy by reducing NAD and FAD
31
outline the steps in the Krebs cycle
1. acetyl group (2C) released from acetylCoA combines with oxaloactate (4C) to form citrate (6C)
2. citrate (6C) is decarboxylated and dehydrogenated making a 5C compound, 1 CO2 and 1 NADH
3. 5C compound is further decarboxylated and dehydrogenated making a 4C compound, 1 CO2 and 1 NADH
4. **4C compound combines temporarily with and the released from CoA. Substrate level phosphorylation produces 1 ATP**
5. 4C compound combines is dehydrogenated making 4C compound and 1FADH
6. 4C compound is rearranged by isomerase enzymes, then dehydrogenated producing 1 NADH. Oxaloacetate is regenerated
32
how many turns of the Krebs cycle for every glucose molecule
2
33
how many NADH are produced per glucose molecule in the link reaction and Krebs cycle
- 2 in link
- 6 in Krebs
34
how many FADH are produced per glucose molecule in the link reaction and Krebs cycle
- 0 in link
- 2 in Krebs
35
how many CO2 are produced per glucose molecule in the link reaction and Krebs cycle
- 2 in link
- 4 in Krebs
36
how many ATP are produced per glucose molecule in the link reaction and Krebs cycle
- 0 in link
- 2 in Krebs
37
what other substances can be respired
- fatty acids
- glycerol
- amino acids
38
what's chemiosmosis
flow of protons, down their conc gradient, across a membrane, through a channel associated with ATP synthase
39
what's oxidative phosphorylation
formation of ATP using energy released in ETC and in the presence of O2. Last stage in aerobic respiration
40
outline the stages in oxidative phosphorylation
1. NADH and FADH are reoxidised when they deliver their H atoms to the ETC
2. H atoms split into H+ and e-
3. H+ go into the solution in mitochondrial matrix
4. e- passed along chain of e- carrier proteins, each contains iron ion which is reduced to Fe2+ and reoxidised to Fe3+, releasing some energy used to pump H+ across the inner mitochondrial membrane, into intermembrane space
5. H+ accumulates in intermembrane space forming a proton gradient across membrane
6. H+ gradient generates chemiosmotic potential
7. H+ diffuses through protein channels associated with ATP synthase, causing a conformational change in the enzyme that makes ADP and Pi combine to make ATP
8. O2 is the final e- acceptor
41
equation showing O2 accepting e-
4H+ + 4e- + O2 ---> 2H2O
42
number of NADH made in glycolysis , link and Krebs per glucose molecule
- 2 in glycolysis
- 2 in link
- 6 in Krebs
43
number of FADH made in glycolysis , link and Krebs per glucose molecule
- 0 in glycolysis
- 0 in link
- 2 in Krebs
44
yield of ATP from oxidative phosphorylation and why
- 28
- H+ and e- from 10NADH can theoretically make 25ATP
- H+ and e- from 2 FADH can theoretically make 3 ATP
45
net gain of ATP per glucose molecule in glycolysis
2
46
net gain of ATP per glucose molecule in the Link reaction
0
47
net gain of ATP per glucose molecule in the Krebs cycle
2
48
net gain of ATP per glucose molecule in oxidative phosphorylation
28
49
total yield of ATP per glucose in respiration
32
50
why is the actual yield of ATP closer to 30
- ATP used to actively transport pyruvate into the mitochondria
- ATP used to transport NADH, made during glycolysis into mitochondria
- some H+ may leak out through outer m.membrane
51
what effect does the absence of O2 have on aerobic respiration
1. O2 can't be the final e- acceptor. H+ can't combine with O2 and e- to form H2O
2. conc of H+ in matrix increases, reducing H+ gradient across inner mitochondrial membrane
3. oxidative phosphorylation ceases
4. NADH and FADH can't unload their H atoms, so not oxidised
5. Krebs and link stop
52
where in the cell does anaerobic respiration occur
cytoplasm
53
which organisms use the lactate fermentation pathway
mammals
54
which organisms use the ethanol fermentation pathway
fungi (yeast) and plants
55
which stage in respiration can still occur without oxygen
- glycolysis but NADH had to be reoxidised for glycolysis to continue, can't do so at ETC so another metabolic pathway needed
56
outline the ethanol fermentation pathway
pyruvate decarboxylated releasing CO2, forms ethanal which is reduced by 2 NADH to form ethanol
57
outline the lactate fermentation pathway
pyruvate reduced by NADH which forms lactate (lactic acid)
58
where are the molecules of pyruvate and NADH used in anaerobic respiration from
glycolysis
59
why is excess lactate toxic
- pH lowered in cells inhibiting action of enzymes involved in glycolysis and muscle contraction
60
how does the body get rid of excess lactate
lactate carried away from muscles, in blood, to the liver where its converted to glucose (gluconeogenesis) and used in respiration or converted to pyruvate and enters Krebs via link
61
what's the net production of ATP from anaerobic respiration per glucose molecule
2 ATP
62
what's a respiratory substrate
an organic substance that can be oxidised by respiration, releasing energy to make ATP
63
examples of respiratory substrates
carbohydrates, lipids and proteins
64
why do lipids produce more ATP than an equivalent mass of carbohydrate
lipids have more H atoms (source of H+ for oxidative phosphorylation)
65
energy value of carbohydrates
15.8
66
energy value of proteins
17.0
67
energy value of lipids
39.4
68
equation for respiratory quotient (RQ)
CO2 produced/ O2 consumed
69
RQ for lipids
0.7
70
RQ for proteins/amino acids
0.8
71
RQ for carbohydrates/ glucose
1
72
what can you deduce from an RQ that's greater than 1
anaerobic respiration is occurring as more CO2 is being produced than O2 being consumed
73
look at respiration experiments...
B5
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