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A-level Biology > 5A - Respiration > Flashcards

5A - Respiration Flashcards

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1
Q

How many types of respiration are there?

A

2

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2
Q

What are the two types of respiration?

A

Aerobic and anaerobic

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3
Q

What do both types of respiration produce?

A

ATP

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4
Q

What stage do both types of respiration start with?

A

Glycolysis

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5
Q

What is the main purpose of glycolysis?

A

To make pyruvate from glucose

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6
Q

What does glycolysis involve?

A

Splitting one molecule of glucose (with 6 carbons - 6C) into two smaller molecules of pyruvate (3C).

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7
Q

Where does glycolysis happen?

A

Cytoplasm.

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8
Q

What is glycolysis?

A

The first stage of respiration (aerobic and anaerobic).

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9
Q

Is glycolysis aerobic or anaerobic?

A

Anaerobic - so doesn’t need oxygen to take place.

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10
Q

How many stages are there in glycolysis?

A

2

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11
Q

What are the 4 main stages of respiration?

A

Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation

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12
Q

How many main stages of aerobic respiration are there?

A

4

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13
Q

What are the 2 stages of glycolysis?

A

Phosphorylation and oxidation.

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14
Q

What happens in the first stage of glycolysis?

A
  • Glucose is phosphorylated using a phosphate from a molecule of ATP. This creates one molecule of glucose phosphate and one molecule of ADP.
  • ATP is then used to add another phosphate, forming hexose bisphosphate.
  • Hexose bisphosphate is then split into 2 molecules of triose phosphate.
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15
Q

What happens in the second stage of glycolysis?

A
  • Triose phosphate is oxidised (loses hydrogen), forming 2 molecules of pyruvate.
  • NAD collects the hydrogen ions, forming 2 reduced NAD.
  • 4ATP are produced, but two were used up in stage one, so there’s a net gain of 2ATP.
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16
Q

What is the second stage of glycolysis called?

A

Oxidation

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17
Q

What is the first stage of aerobic respiration called?

A

Glycolysis

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18
Q

What is the second stage of aerobic respiration called?

A

Link reaction

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19
Q

What is the third stage of aerobic respiration called?

A

Krebs cycle

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20
Q

What is the fourth stage of aerobic respiration called?

A

Oxidative phosphorylation

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21
Q

What is the net gain of ATP in glycolysis?

A

2ATP

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22
Q

What do NAD and FAD do?

A

Transport hydrogen between molecules (so they can reduce various substances).

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23
Q

What does coenzyme A do?

A

Transfers acetate between molecules.

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24
Q

What is pyruvate converted to in anaerobic respiration after glycolysis?

A

Ethanol or lactate.

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25
Q

What happens to the two molecules of reduced NAD produced in glycolysis in aerobic respiration?

A

They go to oxidative phosphorylation.

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26
Q

What happens to the two pyruvate molecules produced in glycolysis in aerobic respiration?

A

They are actively transported into the matrix of the mitochondria for the link reaction.

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27
Q

In what is pyruvate converted into ethanol in anaerobic respiration?

A

In plants and yeast (alcoholic fermentation).

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28
Q

In what is pyruvate converted into lactate in anaerobic respiration?

A

Animal cells and some bacteria (lactate fermentation).

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29
Q

What converts the pyruvate produced in glycolysis into ethanol/lactate in anaerobic respiration?

A

Reduced NAD.

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30
Q

What does the production of ethanol/lactate do?

A

Regenerates oxidised NAD.

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31
Q

What does the production of ethanol/lactate mean can happen?

A

Means glycolysis can continue even when there isn’t much oxygen around, so a small amount of ATP can still be produced to keep some biological processes going.

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32
Q

What is the second part of aerobic respiration?

A

The link reaction.

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33
Q

What is the main thing that happens in the link reaction?

A

Pyruvate is converted to acetyl coenzyme A.

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34
Q

What are the steps to the link reaction?

A

1) Pyruvate is decarboxylated (one carbon is removed from pyruvate in the form of CO2).
2) Pyruvate is oxidised to form acetate and NAD is reduced to form reduced NAD.
3) Acetate is combined with coenzyme A (CoA) to form acetyl coenzyme A (acetyl CoA).
4) No ATP is produced in this reaction.

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35
Q

How much ATP is produced in the link reaction?

A

None.

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36
Q

How often does the link reaction occur?

A

Occurs twice for every glucose molecule.

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37
Q

Why does the link reaction happen twice for every glucose molecule?

A

Because two pyruvate molecules are made for every glucose molecule that enters glycolysis meaning that the link reaction and the third stage ( the Krebs cycle) happen twice for every glucose molecule.

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38
Q

How many molecules of acetyl coenzyme A go into the Krebs cycle for each molecule of glucose?

A

2

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39
Q

How many molecules of CO2 are released as a waste product of respiration for each molecule of glucose?

A

2

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40
Q

How many molecules of reduced NAD are formed and go to the last stage (oxidative phosphorylation) for each molecule of glucose?

A

2

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41
Q

What does the Krebs cycle produce?

A

Reduced coenzymes and ATP.

42
Q

What does the Krebs cycle involve happening?

A

A series of oxidation-reduction reactions, which take place in the matrix of the mitochondria.

43
Q

Where does the link reaction take place?

A

In the matrix of the mitochondria.

44
Q

Where does the Krebs cycle take place?

A

In the matrix of the mitochondria.

45
Q

How often does the Krebs cycle occur?

A

Happens once for every pyruvate molecule, so it goes round twice for every glucose molecule.

46
Q

What happens in the Krebs cycle?

A

1) - Acetyl CoA from the link reaction combines with a four-carbon molecule (oxaloacetate) to form a six-carbon molecule (citrate).
- Coenzyme A goes back to the link reaction to be used again.

2) - The 6C citrate molecule is converted to a 5C molecule.
- Decarboxylation occurs, where CO2 is removed.
- Dehydrogenation also occurs, where hydrogen is removed.
- The hydrogen is used to produce reduced NAD from NAD.

3) - The 5C molecule is then converted to a 4C molecule.
- Decarboxylation and dehydrogenation occur producing one molecule of reduced FAD and two of reduced NAD.
- ATP is produced by the direct transfer of a phosphate group from an intermediate compound to ADP. When a phosphate group is directly transferred from one molecule to another it’s called substrate-level phosphorylation. Citrate has now been converted into oxaloacetate.

47
Q

What happens to the coenzyme A that is produced in the Krebs cycle one the acetyl CoA has been used?

A

It goes back to the link reaction to be used again.

48
Q

What is the hydrogen formed in dehydrogenation in the Krebs cycle used for?

A

Used to produce reduced NAD from NAD.

49
Q

What is it called when a phosphate group is directly transferred from one molecule to another?

A

Substrate-level phosphorylation.

50
Q

Where does the 1 molecule of coenzyme A from the Krebs cycle go?

A

Reused in the next link reaction.

51
Q

Where does the oxaloacetate from the Krebs cycle go?

A

Regenerated for use in the next Krebs cycle.

52
Q

Where does the 2 molecules of CO2 from the Krebs cycle go?

A

Released as a waste product.

53
Q

Where does the 1 molecule of ATP from the Krebs cycle go?

A

Used for energy.

54
Q

Where does the 3 molecules of reduced NAD from the Krebs cycle go?

A

To oxidative phosphorylation.

55
Q

Where does the 1 molecule of reduced FAD from the Krebs cycle go?

A

To oxidative phosphorylation.

56
Q

What does oxidative phosphorylation produce a lot of?

A

ATP

57
Q

What is oxidative phosphorylation?

A

The process where the energy carried by electrons, from reduced coenzymes (reduced NAD and reduced FAD), is used to make ATP.

58
Q

What does oxidative phosphorylation involve?

A

The electron transport chain and chemiosmosis.

59
Q

How does oxidative phosphorylation work?

A

1) Hydrogen atoms are released from reduced NAD and reduced FAD as they’re oxidised to NAD and FAD. The H atoms split into protons (H+) and electrons (e-).
2) The electrons move down the electron transport chain (made up of electron carriers), losing energy at each carrier.
3) This energy is used by the electron carriers to pump protons from the mitochondrial matrix into the intermembrane space.
4) The concentration of protons is now higher in the intermembrane space than in the mitochondrial matrix - this forms an electrochemical gradient (a concentration gradient of ions).
5) Protons then move down the electrochemical gradient, back across the inner mitochondrial membrane and into the mitochondrial matrix, via ATP synthase (which is embedded in the inner mitochondrial membrane). This movement drive the synthesis of ATP from ADP and inorganic phosphate (Pi).
6) This process of ATP production driven by the movement of H+ ions across a membrane (due to electrons moving down an electron transport chain) is called chemiosmosis (which is described by the chemiosmotic theory).
7) In the mitochondrial matrix, at the end of the transport chain, the protons, electrons and O2 (from the blood) combine to form water. Oxygen is said to be the final electron acceptor.

60
Q

What is formed when hydrogen atoms are released from reduced NAD and reduced FAD?

A

NAD and FAD.

61
Q

In oxidative phosphorylation, what does the hydrogen split up into?

A

Protons (H+) and electrons (e-).

62
Q

What is the electron transport chain made up of?

A

Electron carriers.

63
Q

How do electron carriers in the electron transport chain use energy?

A

To pump protons from the mitochondrial matrix into the intermembrane space.

64
Q

What is the intermembrane space?

A

The space between the inner and outer mitochondrial membranes.

65
Q

What is an electrochemical gradient?

A

A concentration gradient of ions.

66
Q

Where is ATP synthase found in the mitochondria?

A

Embedded in the inner mitochondrial membrane.

67
Q

What is the process of ATP production in oxidative phosphorylation driven by the movement of H+ ions across a membrane (due to electrons moving down an electron transport chain) called?

A

Chemiosmosis.

68
Q

What is chemiosmosis described by?

A

The chemiosmotic theory.

69
Q

What is chemiosmosis?

A

The process of ATP production in oxidative phosphorylation driven by the movement of H+ ions across a membrane (due to electrons moving down an electron transport chain).

70
Q

What is said to be the final electron acceptor in oxidative phosphorylation and therefore the whole of aerobic respiration?

A

Oxygen.

71
Q

What combines to form water at the end of oxidative phosphorylation?

A

Protons, electrons and oxygen (from the blood).

72
Q

Where does the oxygen come from in oxidative phosphorylation?

A

The blood.

73
Q

Where do the regenerated coenzymes produced in oxidative phosphorylation go?

A

To the Krebs cycle to be reused.

74
Q

How much energy/ATP can be made from one glucose molecule in aerobic respiration?

A

32 ATP

75
Q

How much ATP is produced per reduced NAD?

A

2.5 ATP

76
Q

How much ATP is produced per reduced FAD?

A

1.5 ATP

77
Q

Show how 32 ATP can be made from one glucose molecule in aerobic respiration

A 
Glycolysis = 2 ATP
Glycolysis = 2 reduced NAD = 2x2.5 = 5 ATP

Link reaction x2 = 2 reduced NAD = 2x2.5 = 5 ATP

Krebs cycle x2 = 2 ATP
Krebs cycle x2 = 6 reduced NAD = 6x2.5 = 15 ATP
Krebs cycle x2 = 2 reduced FAD = 2x1.5 = 3 ATP

Therefore total ATP produced = 2+5+5+2+15+3 = 32 ATP

78
Q

What can ATP production be affected by?

A

Mitochondrial diseases.

79
Q

What do mitochondrial diseases affect?

A

The functioning of the mitochondria.

They can affect how proteins involved in oxidative phosphorylation or the Krebs cycle function, reducing ATP production.

80
Q

What can the fact that mitochondrial diseases can affect how proteins involved in oxidative phosphorylation or the Krebs cycle function, reducing ATP production, cause?

A

May cause anaerobic respiration to increase, to try and make up some of the ATP shortage.

This results in lots of lactate being produced, which can cause muscle fatigue and weakness.

Some lactate will also diffuse into the bloodstream, leading to high lactate concentrations in the blood.

81
Q

Mitochondrial disease may cause anaerobic respiration to increase, to try and make up some of the ATP shortage. What does this result in and why is this bad?

A

This results in lots of lactate being produced, which can cause muscle fatigue and weakness.

Some lactate will also diffuse into the bloodstream, leading to high lactate concentrations in the blood.

82
Q

What can also be used in aerobic respiration other than glucose?

A

Other respiratory substrates - Some products resulting from the breakdown of other molecules, such as fatty acids from lipids and amino acids from proteins, can be converted into molecules that are able to enter the Krebs cycle (usually acetyl coenzyme A).

83
Q

What are other respiratory substrates apart from glucose converted into to be used in the Krebs cycle?

A

Usually acetyl coenzyme A.

84
Q

What are some examples of other respiratory substrates that can be used in aerobic respiration apart from glucose?

A

Some products resulting from the breakdown of other molecules, such as fatty acids from lipids and amino acids from proteins, can be converted into molecules that are able to enter the Krebs cycle (usually acetyl coenzyme A).

85
Q

What is produced in anaerobic respiration in plants?

A

Ethanol.

86
Q

What is the equation for anaerobic respiration in plants?

A

Pyruvate + Reduced NAD –> Ethanol + CO2 + Oxidised NAD.

87
Q

What happens in anaerobic respiration in plants?

A

Pyruvate from the end of glycolysis loses a molecule of CO2 and accepts hydrogen from reduced NAD to produce ethanol.

88
Q

What can the products of anaerobic respiration in plants be used for by humans?

A

Can be used in the brewing industry.

89
Q

What is produced in anaerobic respiration in animals?

A

Lactate.

90
Q

What happens in anaerobic respiration in animals?

A

NAD from glycolysis accumulates and needs to be removed when oxygen is in short supply. Therefore, each pyruvate molecule takes up 2 hydrogen atoms to form the reduced NAD in glycolysis to then form lactate.

91
Q

What is the equation for anaerobic respiration in animals?

A

Pyruvate + Reduced NAD –> Lactate + Oxidised NAD.

92
Q

What can happen to the lactate produced by anaerobic respiration in animals?

A

It can be oxidised back to pyruvate and can then be further oxidised to release energy or can be converted into glycogen once oxygen is available again.

93
Q

What does lactate cause in animals?

A

Cramp and muscle fatigue when it accumulates in the muscle tissue.

It is an acid and so causes pH changes which affects enzymes and their activity.

94
Q

Where in animals does anaerobic respiration mostly occur and why does it occur?

A

In the muscles as a result of strenuous exercise as oxygen debt occurs.

95
Q

What do coenzymes NAD and FAD do?

A
  • Work with enzymes that remove hydrogen atoms from substrates.
  • They carry hydrogen atoms and their electrons.
  • When FAD and NAD gain hydrogen atoms they are reduced.
96
Q

What is special about each electron carrier in oxidative phosphorylation?

A

Each electron carrier is at a lower energy level.

97
Q

What does oxygen serve as in oxidative phosphorylation?

A

The terminal electron acceptor.

98
Q

What does it mean that oxygen serves as the terminal electron acceptor in oxidative phosphorylation?

A

It accepts the electrons/hydrogen ions in oxidative phosphorylation.

99
Q

What happens to oxygen in oxidative phosphorylation?

A

It combines with the electrons from the electron transport chain. It is reduced to form water.

1/2O2 + 2H+ + 2e- –> H2O

100
Q

What happens as protons diffuse through ATP synthase in oxidative phosphorylation?

A

They undergo conformational change and that allows it to couple ADP + Pi to make ATP.

101
Q

What does the conformational change of protons allow in oxidative phosphorylation?

A

Allows the protons to couple ADP + Pi to make ATP.

A-level Biology (42 decks)

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