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Foundations of Medicine > TBL6 Metabolic Pathway > Flashcards

TBL6 Metabolic Pathway Flashcards

1
Q

Glycolysis occurs in the _____ of the cell.

A

cytosol

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2
Q

Glycolysis is an (aerobic/anaerobic) process.

A

anaerobic (does not require oxygen)

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3
Q

______ involves the formation then splitting of a high energy compound in 10 steps.

A

Glycolysis

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4
Q

The first step of glycolysis:

(Enzyme) will catalyse the transfer of a phosphate group from ATP to glucose, forming _______.

A

Hexokinase; forming glucose-6-phosphate

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5
Q

Second step of glycolysis:

Glucose-6-phosphate will be isomerised to form ________, by (enzyme).

A

Forms fructose-6-phosphate; catalysed by phosphoglucose isomerase

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6
Q

Third step of glycolysis:

(Enzyme) will then transfer a phosphate group from ATP to fructose-6-phosphate, forming ___________.

A

Phosphofructokinase; forming fructose-1,6-bisphosphate

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7
Q

4th step of glycolysis:

Fructose-1,6-bisphosphate will then be cleaved by (enzyme) to form ______________ and __________.

A

Cleaved by aldolase; forming

1) glyceraldehyde-3-phosphate
2) dihydroxyacetone phosphate (DHAP)

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8
Q

5th step of glycolysis:

Dihydroxyacetone phosphate (DHAP) will be converted into _________ by (enzyme).

A

converted into glyceraldehyde-3-phosphate; catalysed by triose phosphate isomerase (TPI)

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9
Q

____ deficiency can cause lower concentration of GALP in cells, making cellular respiration inefficient.

A

Triose phosphate isomerase (TPI)

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10
Q

6th step of glycolysis:

Glyceraldehyde-3-phosphate (GALP) will undergo oxidation by (enzyme) to form __________.

During this process, ______ is produced by reduction.

A

catalysed by GALP-dehydrogenase; forming 1,3-bisphophoglycerate

NADH is produced (from NAD+).

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11
Q

7th step of glycolysis:

1,3-bisphophoglycerate then undergoes _______ phosphorylation to form 3-phosphoglycerate, catalysed by (enzyme).

Formation of ATP also occurs.

A

substrate-level phosphorylation;

catalysed by phosphoglycerate kinase

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12
Q

8th step of glycolysis:

3-phosphoglycerate is then converted to __________ by (enzyme).

A

2-phosphoglycerate; catalysed by phosphoglycerate mutase

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13
Q

9th step of glycolysis:

2-phosphoglycerate then undergoes _______ by (enzyme) to form phosphoenolpyruvate.

A

dehydration by enolase

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14
Q

10th step of glycolysis:

Phosphoenolpyruvate then undergoes ________ phosphorylation to form ______. This reaction is catalysed by _________.

A

substrate-level phosphorylation; forming pyruvate;

enzyme: pyruvate kinase

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15
Q

The net products of glycolysis from one molecule of glucose are:

A

2 NADH, 2 ATP

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16
Q

Does substrate-level phosphorylation require oxygen?

A

No

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17
Q

After glycolysis, pyruvate can undergo three different pathways under varying conditions:

A

1) Alcoholic fermentation
2) Lactate fermentation
3) Link reaction to acetyl-CoA

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18
Q

In alcoholic fermentation,
pyruvate is first converted to _______ by the enzyme ________.

After which, the intermediate is converted to ethanol by the enzyme _________.

___ is regenerated in the process.

A

Pyruvate is first converted to ethanal by pyruvate decarboxylase via a decarboxylation reaction.

Ethanal is then reduced to form ethanol, catalysed by alcohol dehydrogenase.

NAD+

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19
Q

In lactic acid fermentation,

pyruvate is reduced to lactate by (enzyme). ___ is regenerated in the process.

A

enzyme: lactate dehydrogenase

NAD+ regenerated

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20
Q

Alcoholic fermentation is (reversible/irreversible).

A

irreversible

–> Ethanol CANNOTbe converted back to pyruvate once oxygen is available.

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21
Q

Lactate fermentation is (reversible/irreversible).

A

reversible

–> Lactate can be converted back to pyruvate in the liver to continue aerobic respiration.

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22
Q

________ is an important source of ATP in muscles which buffers the demand for ATP during intense exercise.

A

Creatine phosphate

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23
Q

(Enzyme) will convert creatine phosphate to creatine. It transfers the phosphate group on creatine phosphate to ADP, forming ATP.

A

Creatine kinase

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24
Q

The link reaction occurs in the _______.

A

mitochondrial matrix

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25
Q

The pyruvate dehydrogenase complex consists of 3 enzymes: ?

A

1) Pyruvate decarboxylase
2) Lipoamide-reductase transacetylase
3) Dihydrolipoyl dehydrogenase

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26
Q

The prosthetic group of Pyruvate Decarboxylase enzyme (part of the pyruvate dehydrogenase complex) is:

A

Thiamine pyrophosphate (TPP)

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27
Q

The prosthetic group of Lipoamide-reductase transacetylase is:

A

Lipoamide

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28
Q

The prosthetic group of Dihydrolipoyl dehydrogenase is:

A

FAD

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29
Q

______ is a Vitamin B1 deficiency resulting in damaged PNS, muscle weakness and decreased cardiac output.
This is due to the inability to form ____.

A

Beri-beri; TPP

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30
Q

The first step of the link reaction:

TPP of the pyruvate carboxylase will attack pyruvate and form __________.

A

Hydroxyethyl-TPP

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31
Q

2nd step of the link reaction:

Oxidation and transfer of _______ to lipoamide to form __________.

Lipoamide is reduced in the process.

A

Transfer acetyl group to lipoamide to form acetylipoamide

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32
Q

3rd step of link reaction:

Transfer of _____ group to CoA to produce _______.

A

Transfer of acetyl group to CoA to form acetyl CoA.

33
Q

4th step of link reaction:

Regeneration of oxidised lipoamide by transferring protons to _____ to form _____.

A

Reduced lipoamide transfers protons to FAD to form FADH2.

34
Q

5th step of link reaction:

Regeneration of oxidised FAD by transferring protons to ____ to form NADH.

A

NAD+

35
Q

The products of the link reaction are:

A

2 acetyl-CoA
2 NADH2
2 CO2

36
Q

Acetyl-CoA has a ______ bond which is a high energy linkage that is readily hydrolysed, allowing acetyl-CoA to donate the acetyl group to other molecules.

A

thioester bond

37
Q

The Krebs’ cycle occurs in the _________.

A

mitochondrial matrix

38
Q

Can Krebs’ cycle operate under anaerobic conditions?

A

No

39
Q

The final products of the Krebs’ cycle per glucose molecule are:

A

2 FADH2
6 NADH
4 CO2
2 ATP

40
Q

All enzymes involved in the Krebs’ cycle are soluble proteins in the mitochondrial matrix, except for ________ which lies on the inner mitochondrial membrane.

A

succinate dehydrogenase

41
Q

1st step of TCA cycle:

Acetyl-CoA transfers the acetyl group to _______, forming _________. This is catalysed by __________.

A

Acetyl-CoA transfers the acetyl group to oxaloacetate (4C), forming citrate (6C).
Enzyme: Citrate synthase

42
Q

2nd step of TCA cycle:

Citrate (6C) then undergoes isomerisation to form ________. This is catalysed by _______.

A

Isocitrate;

catalysed by aconitase

43
Q

3rd step of TCA:

Isocitrate (6C) then undergoes oxidative decarboxylation by (enzyme) to form _______.

___ and ___ are produced in the process.

A

Isocitrate undergoes OD to form a-ketogluterate (5C), catalysed by isocitrate dehydrogenase.

NADH and CO2 are produced.

44
Q

4th step of TCA:

a-ketogluterate then undergoes oxidative decarboxylation to form ______.
This is catalysed by ______.

NADH and CO2 are produced.

A

forms succinyl-CoA (4C)

enzyme: a-ketogluterate dehydrogenase

45
Q

5th step of TCA:

Succinyl-CoA then undergoes ________ phophorylation to form ______.

This is catalysed by ________.

___ is formed in the process.

A

Succinyl-CoA then undergoes substrate-level phophorylation to form succinate.

This is catalysed by succinyl-CoA synthetase.

GTP is formed in the process.

46
Q

6th step of TCA:

Succinate (4C) can then undergo oxidation to form _____.

This is catalysed by __________.

A

Fumerate (4C)

This is catalysed by succinate dehydrogenase.

47
Q

7th step of TCA:

Fumerate can then undergo _____ to form malate, catalysed by ______.

A

Reaction: Hydration;

Product: Malate (4C)

Enzyme: Fumerase

48
Q

8th step of TCA:

Malate (4C) can then undergo ________ to form ______, completing the cycle.

Enzyme involved:?

A

Reaction: Oxidation

Product: Oxaloacetate

Enzyme: Malate dehydrogenase

49
Q

Amino acids are first degraded by removing the ______, which is excreted as urea.

A

amino group

50
Q

________ occurs when the amine group is transferred from one amino acid to a keto acid to form a new pair of amino acids and keto acids.

A

Transamination reaction

51
Q

Transamination reactions occur in the _______.

A

liver

52
Q

Alanine (AA) can undergo a transamination reaction with ______ to form pyruvate and ______.

This is catalysed by ________.

A

Alanine + a-ketogluterate –> Pyruvate + Glutamate

Enzyme: Alanine aminotransferase

53
Q

_______ are needed to transport NADH produced in the cytosol during glycolysis to the mitochondria, where it will be used for oxidative phosphorylation.

A

Mitochondrial shuttles

54
Q

The glycerol phosphate shuttle produces ____ ATP per NADH.

A

1.5

55
Q

The glycerol phosphate shuttle involves (enzyme) in the cytosol and the mitochondria.

A

glycerol-3-phosphate dehydrogenase

56
Q

In the glycerol phosphate shuttle,
Cytosolic glycerol-3-phosphate transfers electrons from NADH to _________.

Mitochondrial glycerol-3-phosphate dehydrogenase then transfers the electrons from glycerol-3-phosphate to _____.

A

NADH –> glycerol-3-phosphate –> FAD –> Coenzyme Q (ETC)

57
Q

The malate-aspartate shuttle produces ___ ATP per NADH.

A

2.5

58
Q

Metabolism includes ______ and ______.

A

Catabolism and anabolism

59
Q

Catabolism involves the use of _____ as the electron carrier.

A

NADH

60
Q

Anabolism involves the use of _____ as the electron carrier.

A

NADPH

61
Q

NADPH and NADH binds to different enzymes due to the _______ present on the NADPH, changing its conformation.

A

phosphate group

62
Q

_______ is the process of re-oxidising NADH and FADH2 generated in the earlier parts of metabolism to produce ATP.

A

Oxidative Phosphorylation

63
Q

NADH and FADH2 donates their ____ to the solvent surrounding the enzyme complex, while their ____ join the electron transport chain.

A

donates protons to surrounding; electrons join ETC

64
Q

There are three membrane complexes and 2 mobile carriers on the electron transport chain.
They are:

A

1) NADH dehydrogenase complex
2) Ubiquinone/coenzyme Q
3) Cytochrome b-c1 complex
4) cytochrome-c
5) Cytochrome oxidase

65
Q

Each unit on the ETC has a (higher/lower) affinity for electrons than the previous unit, allowing for sequential electron flow.

A

higher affinity

66
Q

Cytochrome oxidase receives __ electrons from cytochrome c in the final electron transfer step and passes them to _____ to produce water.

A

4 electrons; oxygen

67
Q

Why is molecular oxygen an ideal terminal electron acceptor?

A

It has a high affinity for electrons and provides a driving force for oxidative phosphorylation.

68
Q

NADH donates electrons to _____ (complex) whereas FADH2 donates electrons to ______ (complex).

A

NADH –> NADH dehydrogenase complex

FADH2 –> Succinate dehydrogenase

69
Q

Positive E value –> more easily (reduced/oxidised)

A

reduced

70
Q

Protons are pumped from the _________ to the _______, generating a steep H+ concentration gradient across the membrane.

A

Actively transported from the matrix into the intermembrane space

71
Q

________ (metabolic poison) inhibits the transfer of electrons from iron-sulfur centres in NADH dehydrogenase complex to ubiquinone.

A

Rotenone

72
Q

_______ (poison) is a competitive inhibitor for succinate dehydrogenase, as it is structurally similar to succinate.

A

Malonate

73
Q

_______ and ____ binds to the Fe3+ of the haem group in the cytochrome oxidase complex with high affinity. Haem group therefore cannot receive any electrons from cyt-c.

A

Cyanide and azides

74
Q

______ is an antibiotic which inhibits oxidative phosphorylation by binding to the stalk of ATP synthase and blocking proton flow through the enzyme.

A

Ogliomycin

75
Q

________ transports protons across the inner mitochondrial membrane, uncoupling oxidative phosphorylation from ATP production.

This markedly increases the metabolic rate and body temperature.

A

Dinitrophenol

76
Q

________ is responsible for the regulated uncoupling of oxidative phosphorylation in newborns and hibernating animals, to generate heat from the dissipation of the proton gradient.

A

Thermogenin (UCP-1)

77
Q

ATP is the inhibitor of _______ (enzyme) in glycolysis. It is therefore the rate-limiting step of glycolysis.

A

Phosphofructokinase

78
Q

Arsenite and mercury have high affinity for sulfhydryl groups in reduced lipoamide, thus inhibiting the _________.

A

pyruvate dehydrogenase complex (PDC)

Foundations of Medicine (21 decks)

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