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Higher Biology Unit 1: Human Cells > 1.7 Cellular Respiration > Flashcards

1.7 Cellular Respiration Flashcards

1
Q

What is cellular respiration?

A

A series of metabolic pathways that brings about the release of energy from a foodstuff and the regeneration of the high-energy compound adenosine triphosphate (ATP)

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2
Q

What ATP composed of ?

A

Adenosine and 3 inorganic phosphate (Pi) groups

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3
Q

What is stored within a ATP molecule ?

A

Energy

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4
Q

When is the energy released from an ATP molecule?

A

When the bond attaching the terminal phosphate is broken

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5
Q

What is the result when the bond attaching the terminal phosphate is broken?

A

Adenosine diphosphate and inorganic phosphate

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6
Q

What is the energy released for give 5 examples ?

A

Cellular processes e.g. Muscle contraction
Active transport mitosis/ meiosis (to separate chromosomes)
DNA replication
Protein synthesis

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7
Q

Why is ATP important?

A

it provides a means by which chemical energy is transferred from one type of reaction to another in a living cell.

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8
Q

Why is there a rapid turnover of ATP molecules?

A

as cells require a constant supply of ATP molecule

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9
Q

What is happening at the same time as ATP molecules are being broken down?

A

many are being regenerated from ADP and Pi

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10
Q

What is phosphorylation?

A

an enzyme-controlled process where a phosphate group is added to a molecule.

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11
Q

Give an example of phosphorylation?

A

when an inorganic phosphate combines with ADP to form ATP

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12
Q

What are the 3 main stages respiration is divided into?

A

glycolysis
citric acid cycle
electron transport chain

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13
Q

Where does glycolysis take place ?

A

cytoplasm of a cell

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14
Q

What is not needed for glycolysis to occur?

A

oxygen

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15
Q

Describe overall what happens in glycolysis?

A

a series of enzyme-controlled steps where glucose is broken down into pyruvate

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16
Q

What is glycolysis split into and what are they called?

A

2 enzyme-controlled phases
energy investment phase
energy pay-off phase

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17
Q

What is USED UP in the energy investment phase?

A

2 ATP molecules are used up per molecule of glucose

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18
Q

Why are 2 ATP molecules used up?

A

2 intermediate compounds are phosphorylated (i.e. a phosphate from the breakdown of ATP is added to these compounds)

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19
Q

What does the first of these phosphorylations lead to?

A

a product that can continue to a number of pathways

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20
Q

What is the second phosphorylation catalysed by?

A

an enzyme called phosphofructokinase

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21
Q

What kind of reaction is the second phosphorylation and what does the resulting compound only leads to ?

A

the final stage of the glycolytic pathway

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22
Q

What is produced in the energy pay-off phase?

A

4 ATP

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23
Q

Apart from 4 ATP being produced during the energy payoff phase what else happens?

A

dehydrogenase enzymes release hydrogen ions from some of the compounds in this part of the pathway. These hydrogen ions are picked up by a co-enzyme called NAD which in turn becomes NADH

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24
Q

When will the citric acid cycle take place?

A

if oxygen is present

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25
Q

What happens to the pyruvate in the citric acid cycle?

A

pyruvate is broken down into carbon dioxide and an acetyl gorup.

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26
Q

What happens to the actetyl group?

A

acetyl group binds with coenzyme A to enter the citric acid cycle as acetyl CoA

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27
Q

How is citrate formed?

A

when the acetyl group of acetyl coenzyme A combines with oxaloacetate.

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28
Q

Where does the citric acid cycle take place?

A

the matrix of the mitochondria

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29
Q

What does the highly folded inner membrane give it?

A

larger surface area

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30
Q

During citric acid cycle, what do dehydrogenase enzymes do?

A

remove hydrogen ions and electrons from the respiratory substrate. These are passed to the coenzyme NAD to form NADH or FAD to form FADH2.

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31
Q

What is produced and what is released during citric acid cycle?

A

ATP is produced

carbon dioxide is released

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32
Q

What does an electron transport chain consist of?

A

a group of protein molecules

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33
Q

Where are many of the electron transport chains found?

A

in a cell

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34
Q

Where are electron transport chains found attached to?

A

the inner membrane of mitochondria called cristae

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35
Q

What do NADH and FADH2 from the glycolytic and citric acid pathways do?

A

release high-energy electrons and pass them to the electron transport chains

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36
Q

What do electrons begin in?

A

a high-energy state

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37
Q

What happens to electrons as they flow along a chain of electron acceptors?

A

they release energy

38
Q

What is the energy from the electrons used to do?

A

pump hydrogen ions across the membrane from the inner cavity (matrix) side to the intermembrane space,where a higher concentration of hydrogen ions is maintained

39
Q

After the hydrogen ions are pumped across to the intermembrane space, what happens to the hydrogen ions?

A

they move by diffusion and this returns the flow of hydrogen ions to the matrix drives ATP synthase to synthesise ATP from ADP + Pi

40
Q

When the electrons come to the end of the electron transport chain, what do they combine with?

A

oxygen, the final electron acceptor, to form water

41
Q

What does the electron transport chain provide?

A

Most of the energy (ATP) in cellular respiration

42
Q

How much ATP is generated in aerobic respiration?

A

38

43
Q

How much ATP is generated in glycolysis?

A

2

44
Q

How much ATP is generated in the cirtric acid cycle?

A

2

45
Q

How much ATP is generated in the electron transport chain?

A

34

46
Q

What is the main substrate used in the respiratory pathway?

A

glucose

47
Q

What other substrates can be used in the respiratory pathway?

A 
starch
glycogen 
other sugar molecules e..g. lactose
amino acids
fats
48
Q

What are starch and glycogen examples of?

A

complex carbohydrates

49
Q

What is starch ?

A

a complex carbohydrate stored by plants

50
Q

What is glycogen?

A

a complex carbohydrate stored by animals

51
Q

What are both starch and glycogen composed of?

A

chains of glucose molecules

52
Q

What can starch and glycogen be used in?

A

respiration as they breakdown into glucose molecules

53
Q

What are fats broken down into and when?

A

glycerol and fatty acids when it is required to take part in respiration

54
Q

What is glycerol and fatty acids converted into?

A

Glycerol is converted into a glycolytic intermediate and fatty acids are metabolised into smaller fragments that enter the pathway as acetyl coA for use in the citric acid cycle

55
Q

What are proteins broken down into ?

A

amino acids by digestive enzymes

56
Q

What happens to extra amino acids that are not required for protein synthesis ?

A

they undergo deamination, forming urea and respiratory pathway intermediates

57
Q

During glycolysis, how can the enzyme phosphofructokinase be inhibited?

A

by the accumulation of ATP and/or citrate

58
Q

What is the inhibition of phosphofructokinase by the accumulation of ATP and/or citrate an example of?

A

feedback inhibition

59
Q

What does the feedback inhibition of phosphofructokinase help to do?

A

synchronise and regulate the RATE of glycolysis and the citric acid cycle.

60
Q

Why is the feedback inhibition of phosphofructokinase important to a cell?

A

it prevents the needless buildup of intermediate compounds
ATP is only produced when it is required
It conserves resources

61
Q

What happens to muscle cells during intense exercise?

A

they start to respire anaerobically because they do not achieve an ADEQUATE supply of oxygen from the bloodstream to support an increased level aerobic respiration.

62
Q

If there is an inadequate supply of oxygen what can neither the citric acid cycle nor the electron transport chain not do?

A

generate additional ATP; only glycolysis is able to provide more ATP.

63
Q

What does glycolysis able to generate?

A

2NADH and 2ATP from each molecule of glucose as it is broken down to pyruvate

64
Q

What happens to the pyruvate if there is an inadequate supply of oxygen?

A

it is converted to lactate and this is accompainied by the transfer of hydrogen from NADH and the regeneration of NAD.

65
Q

Why must NAD present?

A

to enable glycolysis to continue and produce more ATP

66
Q

What does a build up of lactate in muscle cells cause?

A

fatique and an oxygen debt builds up

67
Q

What happens when exercise stops?

A

energy generated by aerobic respiration is now used to convert lactate back to pyruvate

68
Q

During intense muscular activity, what do muscle cells do?

A

breakdown ATP to release energy

69
Q

What do muscle cells contain?

A

a small store of ATP, which can supply energy for only a few muscle contractions

70
Q

What is the chemical which provides much of the energy needed for intense muscular activity?

A

creatine phosphate

71
Q

What does creatine phosphate do?

A

breaks down to release energy and phosphate that is used to convert ADP to ATP at a fast rate.

72
Q

What the creatine phosphate system only support?

A

strenuous muscle activity for around 10 seconds, when the creatine phosphate supply runs out.

73
Q

When is the supply of creatine phosphate restored ?

A

when energy demands are low

74
Q

Why are skeletal muscle fibres required by the body?

A

to bring about all kinds of movemenr

75
Q

What are the 2 types of skeletal muscle fibres?

A

slow-twitch muscle fibres

fast-twitch muscle fibres

76
Q

When are slow-twitch muscle fibres most effective and why?

A

during endurance activities such as long-distance running as they can work for a long time without getting tired

77
Q

What speed do slow-twitch muscle fibres contract?

A

slowly

78
Q

What do slow-twitch muscle fibres depend on?

A

aerobic respiration to generate most of their ATP

79
Q

What number of mitochondria do slow-twitch muscle fibres have?

A

large

80
Q

When are fast-twitch muscle fibres most effective?

A

during power events such as weight-lifting

81
Q

What speed do fast-twitch muscle fibres contract?

A

quickly

82
Q

What is the length of time contraction is sustained in a fast-twitch muscle fibre?

A

short periods of time, but get tired fast, as they consume lots of energy.

83
Q

What do fast-twitch muscle fibres depend on?

A

glycolysis to generate ATP

84
Q

What number of mitochondria do fast-twitch muscle fibres have?

A

small

85
Q

What blood capillary density do fast-twitch muscle fibres have?

A

low

86
Q

What blood capillary density do slow-twitch muscle have?

A

high

87
Q

What concentration of myoglobin do fast-twitch muscle fibres have?

A

low

88
Q

What concentration of myoglobin do slow-twitch muscle fibres have?

A

high

89
Q

What is myoglobin?

A

an oxygen-storing protein present in muscle cells

90
Q

What major storage fuels are used in slow-twitch muscle fibres?

A

fats

91
Q

What major storage fuels are used in fast-twitch muscle fibres?

A

glycogen and creatine phosphate

Higher Biology Unit 1: Human Cells (8 decks)

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