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Biology A2 content > 3.5.2 Respiration > Flashcards

3.5.2 Respiration Flashcards

1
Q

what are the products of glycolysis?

A

2x pyruvate molecules per glucose molecule

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2
Q

what is glycolysis?

A

first part of cellular respiration in which glucose is broken down anaerobically in the cytoplasm

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3
Q

what is the krebs cycle?

A

series of aerobic biochemical reactions in the matrix of the mitochondria of most eukaryotic cells by which energy is obtained through the oxidation of acetylcoenzyme A produced from the breakdown of glucose

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4
Q

what is the link reaction?

A

the process linking glycolysis with the Krebs cycle in which hydrogen and carbon dioxide are removed from pyruvate to form acetylcoenzyme A in the matrix of the mitochondria

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5
Q

what is oxidation?

A

chemical reaction involving the loss of electrons

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6
Q

what is oxidative phosphorylation?

A

formation of ATP in the electron transport system of aerobic respiration

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7
Q

where does the Krebs cycle take place?

A

mitochondria matrix

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8
Q

what four stages could we split aerobic respiration into?

A

glycolysis
link reaction
Krebs cycle
electron transport chain

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9
Q

which of the 4 stages of aerobic respiration does NOT contain oxygen?

A

glycolysis

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10
Q

where does glycolysis occur?

A

in the cytoplasm of ALL living things

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11
Q

what does glycolysis involve?

A

splitting of a hexose sugar (usually glucose) into two molecules of the 3 carbon pruvate / pyruvic acid

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12
Q

what are the products of glycolysis?

A

2 ATP molecules
2 reduced NAD (NADH)
2 molecules of pyruvate

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13
Q

what are the three coenzymes?

A

NAD, FAD, CoA

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14
Q

what occurs in the first stage of glycolysis?

A

activation of glucose by phosphorylation
2 molecules of ATP hydrolyse
2 phosphate molecules (from ATP) added to the glucose molecule and makes it more reactive
Lowers activation energy

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15
Q

what happens in the second stage of glycolysis?

A

Splitting of the phosphate glucose
each glucose is split into two 3 carbon molecules of triosphosphate

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16
Q

what occurs in stage 3 of glycolysis?

A

oxidation of triose phosphate
produces 2 reduced NADs overall

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17
Q

what happens in the 4th stage of glycolysis?

A

the production of ATP
enzyme controlled reaction convert each triose phosphate into another 3 carbon molecule (pyruvate)
2 molecules of ATP are produced from ADP (4 in total)

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18
Q

what is the net gain of ATP for glycolysis?

A

2

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19
Q

in anaerobic respiration in plants, what is produced?

A

ethanol and carbon dioxide

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20
Q

in anaerobic respiration in animals, what is produced?

A

lactate

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21
Q

what happens during anaerobic respiration in plants?

A

glycolysis
decarboxylation of pyruvates - 2C compound
reduced by NADH
produces ethanol as waste product

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22
Q

what is the first stage of respiration?

A

glycolysis

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23
Q

what happens during phosphorylation in glycolysis?

A

glucose is phosphorylated with phosphates from ATP

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24
Q

what happens during oxidation in glycolysis?

A

2 triosphosphates oxidised producing 2 reduced NAD

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25
Q

what is the only stage common to both aerobic and anaerobic respiration?

A

glycolysis

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26
Q

why is the production of reduced NAD important?

A

it donates H ions during anaerobic respiration in order to produce ethanol and CO2

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27
Q

where do the products of glycolysis go?

A

to the mitochondria (if oxygen present)

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28
Q

why is the ATP from glycolysis only 2?

A

2 are used

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29
Q

what happens to the pyruvates in the link reaction?

A

decarboxylation and oxidation to form acetic acid/acetate and CO2 (+ coenzymeA)

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30
Q

where does the link reaction take place?

A

mitochondria matrix

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31
Q

what is the second stage of respiration?

A

the link reaction

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32
Q

what is the role of acetyl coenzyme A in the link reaction?

A

‘collect’ the acetate/acetic acid and transport it to the Krebs cycle

33
Q

describe how acetyl coenzyme A is formed in the link reaction.

A

pyruvate is carboxylated and oxidised to form acetate and CO2, coenzyme A added to acetate

34
Q

what is the first step of the Krebs cycle

A

oxaloacetate (4C) and acetyl coenzymeA (2C) combine and lose CoA - which goes back to the link reaction - producing citrate (6C)

35
Q

what happens in the second step in the Krebs cycle?

A

citrate is decarboxylated and oxidised (oxidative carboxylation) to form a 5C compound

36
Q

what is the third step in the Krebs cycle?

A

regeneration of oxaloacetate
5C compound is decarboxylated
5C compound is oxidised 3 times with 2 producing reduced NAD and 1 producing reduced FAD
substrate level phosphorylation
producing oxaloacetate

37
Q

what does each Krebs cycle produce?

A

3 molecules of NADH
1 ATP
2 carbon dioxide
1 FADH2

38
Q

for each glucose how many turns of the Krebs cycle are there?

A

2

39
Q

where does the Krebs cycle take place?

A

mitochondria matrix

40
Q

how is citrate formed?

A

oxaloacetate + acetyl coA

41
Q

how many molecules of reduced NAD are produced in the Krebs cycle per molecule of glucose?

A

6

42
Q

how many carbons are in acetyl coA?

A

2

43
Q

how many carbons are in pyruvic acid?

A

3

44
Q

how many carbons are in triose phosphate?

A

3

45
Q

how many carbons are in citric acid?

A

6

46
Q

how many carbons are in oxaloacetate?

A

4

47
Q

what does the link reaction convert pyruvate into?

A

acetic acid

48
Q

what happens in oxidative phosphorylation?

A

hydrogen and electrons carried by coenzymes is used to synthesise ATP

49
Q

what does oxidative phosphorylation involve?

A

ETC and chemiosmosis

50
Q

where are the enzymes and proteins involved in the ETC located?

A

cristae of mitochondria

51
Q

what is in the process of oxidative phosphorylation?

A

electrons from oxidation of NADH and FADH are transported in the ETC where they lose energy
H ions from oxidation of NAD and FAD are actively transported through the cristae into the intermembrane space using energy lost by electrons in the ETC.
H ions move back into matrix through ATP synthase which synthesises ATP.

52
Q

what is the final electron acceptor in oxidative phosphorylation?

A

formation of water

53
Q

what is decarboxylation?

A

loss of CO2

54
Q

name the 4 main stages in aerobic respiration and where they occur.

A

Glycolysis: cytoplasm
Link reaction: mitochondrial matrix
Krebs cycle: mitochondrial matrix
Oxidative phosphorylation via electron transfer chain: membrane of cristae

55
Q

How does pyruvate from glycolysis enter the mitochondria?

A

active transport

56
Q

give a summary equation for the link reaction.

A

pyruvate + NAD + CoA —> acetyl CoA + reduced NAD + CO2

57
Q

what happens in the Krebs cycle?

A

series of redox reactions produces:
- ATP by substrate-level phosphorylation
- Reduced coenzymes
- CO2 from decarboxylation

58
Q

what is the electron transfer chain (ETC)?

A

Series of carrier proteins embedded in membrane of the cristae of mitochondria
Produces ATP through oxidative phosphorylation via chemiosmosis during aerobic respiration.

59
Q

What happens in the ETC?

A

Electrons released from reduced NAD & FAD undergo successive redox reactions.
The energy released is coupled to maintaining proton gradient or released as heat.
Oxygen acts as final electron acceptor

60
Q

How is a H+ concentration gradient established during chemiosmosis in aerobic respiration?

A

Some energy released from the ETC is coupled to the active transport of H+ ions (protons) from the mitochondrial matrix into the intermembrane space

61
Q

How does chemiosmosis produce ATP during aerobic respiration?

A

H+ ions (protons) move down their concentration gradient from the intermembrane space into the mitochondrial matrix via the channel protein ATP synthase
ATP synthase catalyses ADP + Pi –> ATP

62
Q

state the role of oxygen in aerobic respiration.

A

final electron acceptor in electron transfer chain.
(produces water as a byproduct)

63
Q

what is the benefit of an electron transfer chain rather than a single reaction?

A
  • energy is released gradually
  • less energy is released as heat
64
Q

name two types of molecule that can be used as alternative respiratory substrates.

A
  • (amino acids from) proteins
  • (glycerol and fatty acids from) lipids
65
Q

How can lipids act as an alternative respiratory substrate?

A

lipid –> glycerol + fatty acids
1. Phosphorylation of glycerol –> TP for glycolysis
2. Fatty acids –> acetate
a) acetate enters link reaction
b) H atoms produced for oxidative phosphorylation

66
Q

How can amino acids act as an alternative respiratory substrate?

A

Deamination produces:
1. 3C compounds –> pyruvate for link reaction
2. 4C/ 5C compounds –> intermediates in Krebs cycle

67
Q

Name the stages in respiration that produce ATP by substrate-level phosphorylation

A
  • glycolysis (anaerobic)
  • Krebs cycle (aerobic)
68
Q

what happens during anaerobic respiration in animals?

A

Only glycolysis continues reduced NAD + pyruvate –> oxidised NAD (for further glycolysis) + lactate

69
Q

what happens to the lactate produced in anaerobic respiration?

A

Transported to liver via bloodstream, where it is oxidised to pyruvate
Can enter link reaction in liver cells or be converted to glycogen

70
Q

What happens during anaerobic respiration in some microorganisms e.g. yeast and some plant cells?

A

only glycolysis continues
Pyruvate is decarboxylated to form ethanal
Ethanal is reduced to ethanol using reduced NAD to produce oxidised NAD for further glycolysis.

71
Q

What is the advantage of producing ethanol/ lactate during anaerobic respiration?

A

converts reduced NAD back into NAD so glycolysis can continue

72
Q

What is the disadvantage of producing ethanol during anaerobic respiration?

A
  • Cells die when ethanol concentration is above 12%
  • Ethanol dissolves cell membranes
73
Q

What is the disadvantage of producing lactate during anaerobic respiration?

A

Acidic, so decreases pH
Results in muscle fatigue

74
Q

What are the similarities between aerobic and anaerobic respiration?

A
  • Both involve glycolysis
  • Both require NAD
  • Both produce ATP
75
Q

What are the differences between aerobic and anaerobic respiration?

A
  • Aerobic produces ATP by substrate-level phosphorylation AND oxidative phosphorylation whereas anaerobic produces ATP by substrate-level phosphorylation only.
  • Aerobic produces much more ATP than anaerobic
  • aerobic does not produce ethanol or lactate whereas anaerobic does.
76
Q

Suggest how a student could investigate the effect of a named variable on the rate of respiration of a single-celled organism.

A
  1. Use respirometer (pressure changes in boiling tube cause a drop of coloured liquid to move).
  2. Use a dye as the terminal electron acceptor for the ETC.
77
Q

What is the purpose of sodium hydroxide solution in a respirometer set up to measure the rate of aerobic respiration?

A

Absorbs CO2 so that there is a net decrease in pressure as O2 is consumed.

78
Q

How could a student calculate the rate of respiration using a respirometer?

A

Volume of O2 produced or CO2 consumed / time x mass of sample
volume = distance moved by coloured drop x (0.5 x capillary tube diameter) squared x pi

Biology A2 content (19 decks)

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