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CELLS > Cell Metabolism > Flashcards

Cell Metabolism Flashcards

1
Q

What does glycolysis produce?

A

2 x Pyruvate
2 x NADH
2 x Net ATP

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2
Q

What reaction is irreversible and commits the cell to glycolysis?

A

The conversion of glucose to glucose - 6 - phosphate

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3
Q

What is the complete reaction steps of glycolysis?

A

Glucose
Glucose - 6 - Phosphate
Fructose - 6 - Phosphate
Fructose - 1,6 - Bisphosphate –> dihydroxyacetone phosphate and
Glyceraldehyde - 3 - Phosphate
1,3 - Bisphosphoglycerate
3 - Phosphoglycerate
2 - Phosphoglycerate
Phosphenolpyruvate
Pyruvate

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4
Q

Which step of glycolysis does phosphofructokinase control?

A

The conversion of fructose - 6 - phosphate into fructose - 1,6 - bisphosphate

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5
Q

What does TPI stand for?

A

Triose phosphate isomerase

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6
Q

What does hexokinase catalyse?

A

The conversion of glucose into glucose - 6 - phosphate

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7
Q

What is the only glycolytic enzymopathy which is fatal?

A

Deficiency in TPI

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8
Q

Which reactions produce ATP?

A

The conversion of 1,3-Bisphosphoglycerate into 3-phosphglycerate and phosphenolpyruvate into pyruvate

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9
Q

What do kinases do?

A

Transfer phosphate groups to molecules

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10
Q

Which step in glycolysis needs NAD+?

A

Glyceraldehyde - 3 - phosphate into 1,3 - bisphosphoglycerate

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11
Q

Which steps of glycolysis require ATP?

A

Glucose -> glucose - 6 - phosphate
Fructose - 6 - phosphate -> Fructose - 1,6 - bisphosphate

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12
Q

Does glycolysis need oxygen to occur?

A

No - it is anaerobic

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13
Q

Where does glycolysis occur?

A

In the cytoplasm

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14
Q

Why are high energy phosphate groups added to some of the substrates involved in glycolysis?

A

Adding the phosphate groups makes them easier to split as they are more reactive

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15
Q

What are the three fates of pyruvate?

A
  1. Lactate generation
  2. Acetyl CoA Production
  3. Alcohol fermentation
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16
Q

What enzyme is needed to generate Acetyl CoA from pyruvate?

A

Pyruvate dehydrogenase complex

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17
Q

What does pyruvate dehydrogenase needed as a cofactor?

A

Thiamine

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18
Q

What does a deficiency in thiamine result in?

A

Beri - Beri
This is a condition which leads to muscle weakness

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19
Q

How is pyruvate converted into lactate?

A

Using lactate dehydrogenase complex

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20
Q

What does the fermentation of alcohol and lactate production both regenerate?

A

NAD+ - this is needed for glycolysis to continue occurring

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21
Q

What happens to the Acetyl CoA that is produced?

A

It enters into the Krebs Cycle

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22
Q

What are the stages of the Krebs Cycle?

A

Acetyl CoA combines with oxaloacetate to make Citrate
Then Alpha - keto glutarate
Succinyl CoA
Succinate
Fumerate
Malate

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23
Q

What does the Krebs cycle produce?

A

2 x CO2
1 x GTP
3 x NADH
1 x FADH

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24
Q

What reaction in the Krebs cycle produces FADH?

A

The conversion of succinate to fumerate

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25
Q

Where does the krebs cycle occur?

A

The mitochondrial matrix

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26
Q

What is a transamination reaction?

A

the process of removing an amine group from one amino acid and transferring it to a ketoacid, producing another ketoacid and amino acid

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27
Q

What are the seven things which can be produced from transamination reactions?

A

Pyruvate
Succinyl CoA
Acetoacetyl CoA
Acetyl CoA
Oxaloacetate
Alpha Keto Glutarate
Fumerate

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28
Q

Explain Alcoholic Fermentation of Pyruvate

A

Pyruvate is converted into Acetaldehyde using pyruvate decarboxylase. Then using alcohol dehydrogenase is used to convert the acetaldehyde into ethanol

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29
Q

Why is it essential that NAD+ is regenerated?

A

Needed for dehydrogenation of glyceraldehyde-3-phosphate to produce ATP

Allows glycolysis to occur anaerobically

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30
Q

What is the Warburg effect?

A

Mutations in genes of Fumerase, Succinate, Isocitrate Dehydrogenase, decreases Kreb’s Cycle activity which enhances anaerobic glycolysis

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31
Q

What are glucogenic amino acids?

A

Ones whose carbon skeletons are used to make glucose

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32
Q

What are ketogenic amino acids?

A

Amino acids which when they are broken down, form ketone body precursors like Acetyl CoA

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33
Q

During fasting, which type of metabolism dominates?

A

fat metabolism, resulting in the production of ketone bodies

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34
Q

What happens when the levels of Acetyl CoA is not equal to Oxaloacetate?

A

The excess Acetyl CoA is used to make ketone bodies

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35
Q

What are the names of the three ketone bodies?

A

Acetone, Acetoacetate and 3 - Beta - Hydroxy Butyrate

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36
Q

Why can ketone bodies be utilised by the brain but fatty acids cannot?

A

Fatty acids can’t cross the blood brain barrier

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37
Q

What is the purpose of the Glycerol Phosphate Shuttle

A

To carry electrons from NADH across the matrix - this is because the mitochondrial matrix is impermeable to NADH

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38
Q

Where in the body is the Glycerol-Phosphate Shuttle used?

A

brain and skeletal muscle

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39
Q

Explain how the Glycerol-Phosphate Shuttle works

A

Cytosolic glycerol-3-phosphate dehydrogenase transfers electrons from NADH to DHAP → Glycerol-3-Phosphate

The G-3-P is then converted back into DHAP, and FAD is reduced to form FADH2

The FADH2 electrons are then passed onto molecule Q which is in the electron transport chain

40
Q

Where in the body is the Malate-Aspartate Shuttle used?

A

Liver, kidney and the heart

41
Q

Outline the processes in the Malate-Aspartate Shuttle

A

Malate enters into the matrix NADH is generated from NAD+ which then regenerates oxaloacetate

42
Q

What is a ligation requiring ATP cleavage reaction?

A

Formation of covalent bonds eg carbon-carbon bonds

43
Q

What is an isomerisation reaction?

A

The rearrangement of atoms to form isomers

44
Q

What is a group transfer reaction?

A

The transfer of a function group from one molecule to another

45
Q

What is a hydrolytic reaction?

A

The cleavage of bonds by the addition of water

46
Q

What are the two main concepts of glycolysis?

A

The formation of a high energy compound, and the splitting of this compound

47
Q

Why is the generation of NADH useful?

A

NADH is generated here which can be later used to generate yet more ATP within the mitochondria in a process known as oxidative phosphorylation

48
Q

Why is creatine phosphate used as a buffer?

A

In muscle, the amount of ATP needed during exercise is only enough to sustain contraction for around one second.

49
Q

Describe how creatine phosphate is used to generate ATP?

A

Creatine phosphate -> creatine + ATP

50
Q

How is creatine used by athletes?

A

As a dietary supplement

51
Q

How is Acetyl CoA able to donate the acetate group (2C) to other molecules?

A

The thioester linkage which it contains is a high energy linkage so is readily hydrolysed

52
Q

What are the symptoms of Beri Beri?

A

damage to the peripheral nervous system, weakness of the musculature and decreased cardiac output.

53
Q

What enzyme is used in the transamination reaction of alanine?

A

Alanine (C3) undergoes transamination by the action of the enzyme alanine aminotransferase.

54
Q

What does the transamination of alanine produce?

A

Pyruvate and glutamate

55
Q

What type of reaction is occuring in the Malate-Aspartate Shuttle?

A

Transamination reaction

56
Q

Mutations in which TCA genes have been shown to decrease TCA activity and enhance aerobic glycolysis?

A

Isocitrate dehydrogenase
Succinate dehydrogenase
Fumerase

57
Q

How many ATP does the oxidation of one Acetyl CoA produce?

A

12

58
Q

How many ATP molecules are formed by the reoxidation of each NADH?

A

3

59
Q

How many ATP molecules are formed by the reoxidation of each FADH?

A

2

60
Q

What is the name of the process of fatty acid metabolism?

A

Beta oxidation

61
Q

where does beta oxidation occur?

A

In the mitochondria

62
Q

How are fatty acids converted into an Acyl CoA Species?

A

Using Acyl CoA synthetase

63
Q

Where does the generation of Acyl CoA occur?

A

In the outer mitochondrial membrane

64
Q

What is the name of the shuttle used to transport Acyl CoA species into the miatrix?

A

Carnitine shuttle

65
Q

Describe how the carnitine shuttle works?

A

Acyl CoA is coupled to the molecule carnitine to form acyl carnitine - this is done using an enzyme carnitine acyltransferase 1

The acyl carnitine is then shuttle across the membrane via translocase

The acyl Carnitine is then converted back into carnitine and Acyl CoA

66
Q

What is used as a supplement when you have primary carnitine deficiency?

A

Carnitor / levocarnitine

67
Q

What type of deficiency is primary carnitine deficiency?

A

Autosomal recessive disorder

68
Q

What are some symptoms of primary carnitine deficiency?

A

encephalopathies, cardiomyopathies, muscle weakness; and hypoglycaemia

69
Q

Describe the mutations involved in primary carnitine deficiency?

A

Mutations in a gene known as SLC22A5 which encodes a carnitine transporter result in reduced ability of cells to take up carnitine, needed for the β-oxidation of fatty acids.

70
Q

What are the four reactions in Beta-oxidation?

A

oxidation, hydration, oxidation and thiolysis

71
Q

What does one cycle of beta oxidation result in?

A

The produce of Acetyl CoA and an Acyl CoA species which is 2 carbons shorter than the original

72
Q

Write the overall equation for the Beta-Oxidation of palmitoyl CoA?

A

palmitoyl CoA + 7 FAD + 7 NAD+ + 7 H2O + 7 CoA —-> 8 acetyl CoA + 7 FADH2 + 7 NADH

73
Q

What happens to the acetyl CoA generated through beta-oxidation?

A

Enters the TCA cycle only if Beta oxidation and carbohydrate metabolism are balanced, as oxaloacetate is needed for entry

74
Q

What does Acetyl CoA form during fasting?

A

D-3-hydroxybutyrate, Acetone and Acetoacetate

75
Q

What is fatty acid biosynthesis known as?

A

Lipogenesis

76
Q

What are the two enzymes involved in fatty acid biosynthesis?

A

Acetyl CoA Carboxylase and fatty acid synthesis

77
Q

What are the three enzymes which are involved in lipogenesis?

A

Ketoreductase, dehydratase and enol reductase

78
Q

During lipogenesis, what is the growing fatty acid group linked to?

A

An Acyl carrier protein

79
Q

What are the differences in carriers between synthesis and degradation of fatty acids?

A

Carriers - synthesis uses Acyl Carrier Protein while degradation uses CoA

80
Q

What are the differences in reducing powers between synthesis and degradation of fatty acids?

A

Synthesis uses NADPH but degradation uses FAD/NAD+

81
Q

What are the differences in location between synthesis and degradation of fatty acids?

A

Synthesis occurs in the cytoplasm, but fatty acids degradation occurs in the mitochondrial matrix

82
Q

What is the overall reaction of lipogenesis, to form Palmitate?

A

Acetyl CoA (C2) + 7 Malonyl CoA (C3) + 14 NADPH +14 H+
—-> Palmitate (C16) + 7 CO2+ 6 H2O + 8 CoA-SH + 14 NADP+

83
Q

What does the desaturation of fatty acids required?

A

the action of fatty acyl-CoA desaturases

84
Q

What is the enzyme that creates oleic acid and palmitoleic acid from stearate and palmitate, respectively called?

A

∆-9 desaturase

85
Q

In adults where is de novo Faty acid biosynthesis restricted to?

A

The liver, adipose tissue and lactating breasts

86
Q

What is meant by Acyl-CoA-dehydrogenase specificity?

A

Each acyl-CoA-dehydrogenase can bind a fatty acid chain of varying lengths

87
Q

What is MCADD?

A

Medium chain Acyl CoA dehydrogenase deficiency

88
Q

What type of diet should patients with MCADD sick to?

A

A high carbohydrate diet

89
Q

What must patients with MCADD need it their illness manifests as apetite loss or severe vomiting?

A

i.v glucose to make sure their body is not dependant on fatty acids for energy

90
Q

How can MCADD be treated?

A

Lifestyle adaptations

91
Q

How are fats stored in the adipocytes?

A

As triglycerides

92
Q

What are triglycerides broken down into?

A

glycerol and fatty acids using lipase

93
Q

How many ATP does the generation of the Fatty Acyl CoA need?

A

2

94
Q

What is the net gain of ATP per molecules of palmitoyl?

A

129 ATP

95
Q

How many NADH and FADH2 does beta oxidation produce?

A

1 of each

96
Q

What is TPI needed for?

A

Converstion of DHAP into G-3-P

97
Q

What is the only fatal enzyme glycoltic enzymopathy?

A

TPI deficiency

CELLS (15 decks)

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