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MCD Year 1 > Metabolism > Flashcards

Metabolism Flashcards

1
Q

What is the simplest amino acid?

A

Glycine

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2
Q

What amino acid is formed if the R group is CH3?

A

Alanine

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3
Q

If an amino acid has non-polar side chains what does this make the amino acid?

A

Hydrophobic

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4
Q

If an amino acid has polar side chains what does this make the amino acid?

A

Hydrophillic

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5
Q

What ability gives amino acids buffering capability?

A

The ability to take up and release protons

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6
Q

What are enantiomers of amino acids?

A

Mirror images of an amino acid

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7
Q

in what form are amino acids in the body?

A

L-form

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8
Q

What reaction forms amino acid peptides?

A

Condensation reaction

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9
Q

What is steric hindrance?

A

Where side chains in a protein do not clash with the main chain

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10
Q

What bond is present in disulphide bridges?

A

Covalent bonds

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11
Q

What are Van der Waals forces?

A

Transient, weak electrostatic attraction between atoms. Requires closeness

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12
Q

Where does an alpha helix bond form?

A

The C=O of one amino acid bonds to the N-H four amino acids along bonds to stabilise the structure

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13
Q

What amino acid causes kinks in the alpha helix chain?

A

Proline

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14
Q

What is a primary protein structure?

A

The linear structure- the amino acid sequence

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15
Q

What is a secondary protein structure?

A

The alpha-helices and beta-pleated sheets

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16
Q

What is a tertiary protein structure?

A

Arrangement of secondary structures into compact globular structures called domains

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17
Q

What is quaternary protein structure?

A

The 3D structure of a multimeric protein that has multiple polypeptide chains eg haemiglobin

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18
Q

Where are γ-carboxyglutamate residues formed in proteins?

A

In clotting factors in the blood clotting cascade

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19
Q

What is the function of γ-carboxyglutamate residues?

A

They are critical for normal clotting function by increasing calcium binding capabilities

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20
Q

How does Warfarin work?

A

Warfarin inhibits the carboxylation reaction of γ-carboxyglutamate residues, reducing the coagulative properties of the clotting factors

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21
Q

What is free energy?

A

The amount of energy within a molecule that could perform useful work at a constant temperature

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22
Q

A reaction can only occur if △G is what?

A

Negative

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23
Q

What is the high energy bond in ATP?

A

Phosphoanhydride bonds

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24
Q

What do enzymes do to the rate of reaction and the activation energy?

A

The increase the rate of reaction and lower the activation energy

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25
Q

What do enzymes do to △G?

A

Nothing

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26
Q

What does lysozyme do?

A

Catalyses the hydrolysis of sugar molecules N-acetyl glucosamine (NAG) and N-acetyl muramic acid (NAM within bacterial cell walls that are necessary for their structure.

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27
Q

What are the three stages of metabolism?

A

1) Digestion: Enzymes mediated, liberates small molecules, takes place in the GI tract
2) Cellular metabolism I: Oxidation of small molecules within the cytosol of individual cells generating ATP and NADH
3) Cellular metabolism II: oxidation of small molecules generated by the first stage of cellular metabolism within the mitochondria, generating ATP and waste

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28
Q

What does a deficiency in thiamine (vitamin B1) cause?

A

Beri-Beri

Symptoms include: damage to the peripheral nervous system, weakness of muscles and decreased cardiac output

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29
Q

Where is pyruvate converted into Acetyl-CoA

A

In mitochondria

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30
Q

Where does glycolysis take place?

A

In the cytoplasm of cells

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31
Q

Is glycolysis aerobic or anaerobic?

A

Anaerobic

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32
Q

What is the net ATP gain from glycolysis?

A

2 ATP molecules

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33
Q

What is the net ATP gain from aerobic respiration?

A

38 ATP molecules

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34
Q

What is the high energy bond in Acetyl-CoA?

A

A thioester bond (C-S)

Allows Acetyl-CoA to donate 2C to a molecule (CO-CH3)

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35
Q

How does palmitic acid make Acetyl-CoA?

A

β-oxidation

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36
Q

What are the products of one β-oxidation cycle?

A

1 FADH2
1 NADH
1 Acetyl CoA

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37
Q

What is transamination?

A

A reaction in which an amine group is transferred from one amino acid to a keto acid thereby forming a new pair of amino and keto acids

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38
Q

Persistently high levels of alanine aminotransferase are diagnostic of what?

A

Hepatic disorders such as Hepatitis C

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39
Q

Where does the Kreb’s cycle occur?

A

In the mitochondrial matrix

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40
Q

Is the Kreb’s cycle aerobic or anaerobic?

A

Aerobic

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41
Q

How does NADH + electrons cross from the cytosol to the mitochondrial matrix in skeletal muscle and the brain?

A

Glycerol phosphate shuttle

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42
Q

How does NADH + electrons cross from the cytosol to the mitochondrial matrix in the liver, kidney and heart?

A

Malate-aspartate shuttle

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43
Q

The result of the malate-aspartate shuttle leave NAD+ and NADH where?

A

NAD+ is cytoplasmic

NADH is mitochondrial

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44
Q

How many ATP molecules so you get from oxidative phosphorylation of 1 NADH?

A

3 ATP molecules

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45
Q

How many ATP molecules so you get from oxidative phosphorylation of 1 FADH2?

A

2 ATP molecules

Because the electrons enter at ubiquinone with FADH2

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46
Q

How many ATP molecules do you get from glycolysis?

A

8 ATP molecules

47
Q

How many ATP molecules do you get from one Acetyl-CoA in the Kreb’s cycle?

A

12 ATP molecules

48
Q

How many ATP molecules do you get from palmitate metabolism?

A

129 ATP molecules

49
Q

Where does oxidative phosphorylation occur?

A

In the inner mitochondrial membrane

50
Q

What is oxidative phosphorylation?

A

The process in mitochondria in which ATP formation is driven by the transfer of electrons from food molecules to molecular oxygen. Involves the intermediate generation of a pH gradient across a membrane and chemiosmotic coupling

51
Q

Which subunit and disc of ATP synthase rotates when a proton moved from intermembrane space to the matrix?

A

Disc of subunit c and the attached γ subunit rotate

52
Q

How much ATP does the average human body synthesis per day?

A

70kg

53
Q

How long is the average ATP lifespan?

A

Between 1 and 5 minutes

54
Q

What is the most common cause of a failure in the process of oxidative phosphorylation?

A

Hypoxia (diminished) and Anoxia (Total)

55
Q

How does cyanide affect the electron transport chain?

A

It binds with very high affinity to ferric iron in haem group in the cytochrome oxidase complex. This blocks the flow of electrons through the respiratory chain and consequently, the production of ATP

56
Q

How does carbon monoxide affect the electron transport chain?

A

It binds to the ferrous iron in haem group, blocking the flow of electrons.

57
Q

How does malonate affect the electron transport chain?

A

It closely resembles succinate and acts as a competitive inhibitor of succinate dehydrogenase. It effectively slows down the flow of electrons from succinate to ubiquinone by inhibiting the oxidation of succinate to fumarate

58
Q

How does oligomycin affect the electron transport chain?

A

It is an antibiotic produced by streptomyces that inhibits oxidative phosphorylation by binding with the stalk of ATP synthetase. This blocks the flow of protons through the enzyme. As a result, ATP synthesis is inhibited and a backlog of protons will build up in the intermembrane space. This will eventually inhibit the flow of electrons through the electron transport chain as the outside of the mitochondrion will build up to a saturation point at which no more protons can be pumped out against this proton gradient

59
Q

What is needed to digest and emulsify fats?

A

Bile salts

60
Q

What is steatorrhea?

A

Fatty stools resultant from lack of bile salts

61
Q

β-oxidation is the metabolism of what?

A

Fatty acids

62
Q

Where does β-oxidation occur?

A

In the mitochondrial matrix

63
Q

Fatty acid synthesis uses which two enzymes?

A

Acetyl CoA Carboxylase

Fatty Acid Synthase

64
Q

What are the two molecules needed for lipogensis

A

Acetyl CoA

Malonyl CoA

65
Q

Where does fatty acid synthesis take place?

A

In the cytoplasm

66
Q

What are the 3 types of intracellular transport?

A

1) Gates transport (eg nuclear import)
2) Transmembrane transport (eg import of newly synthesised proteins into ER)
3) Vesicular transport (eg inter-organellar transport)

67
Q

What post translational modifications does the endoplasmic reticulum make?

A 
Folding
Formation of disulphide bonds
Initial glycosylation (addition of sugars)
Specific proteolytic cleavages
Assembly of multimeric proteins
68
Q

Where are unassembled or misfolded proteins retained and exported back to the cytosol to be degraded?

A

The endoplasmic reticulum

69
Q

What is constitutive secretion?

A

Where proteins are secreted from a cell continuously, regardless of external factors or signals

70
Q

What is regulated secretion?

A

Where proteins are stored and secreted on demand in response to a signal eg insulin

71
Q

Describe the process of the receptor-mediated endocytosis of LDL in the liver?

A

LDL binds to LDL receptors and endocytosis occurs into a clathrin-coated vesicle
Uncoating of the vesicle occurs
Fusion with the endosome
Budding off of transport vesicle of LDL receptor
Return of LDL receptor to plasma membrane

72
Q

What does CFTR stand for?

A

Cystic fibrosis transmembrane conductance regulator

73
Q

What is the most common mutation to cause cystic fibrosis and what does it cause?

A

Mutation at △F508 causes a loss of phenylalanine at the 508th position causing the protein to misfold

74
Q

A mutation of what causes familial hypercholesterolaemia?

A

LDL receptor

75
Q

What is from progestagens?

A

Glucocorticoids
Mineralocorticoids
Androgens- Estrogens

76
Q

How are progestagens formed from cholesterol?

A

Cholesterol→Pregnenolone→Progestagens

77
Q

What enzyme converts cholesterol to pregnenolone?

A

Desmolase

78
Q

What is the process of synthesis of vitamin D from cholesterol?

A

7-Dehydrocholesterol→Previtamin D3→Vitamin D3→Calcitriol

79
Q

What is required to convert 7-Dehydrocholesterol to Previtamin D3?

A

Ultraviolet light

80
Q

What bile salts are produced from cholesterol?

A

Glycocholate and taurocholate

81
Q

What is the main breakdown product of cholesterol?

A

Bile salts

82
Q

How big are high-density lipoproteins?

A

8-10nm

83
Q

How big are low-density lipoproteins?

A

20-25nm

84
Q

What is the function of high-density lipoproteins?

A

Take cholesterol from peripheral tissues back to the liver for use of disposal

85
Q

What is the function of low-density lipoproteins?

A

Take cholesterol synthesised in the liver to peripheral tissues

86
Q

What cholesterol is “good cholesterol”?

A

High-density lipoprotein

87
Q

What cholesterol is “bad cholesterol”?

A

Low-density lipoprotein

88
Q

With a single copy of the familial hypercholesterolaemia gene, how much higher is your cholesterol?

A

2-3 times higher

89
Q

With a two copies of the familial hypercholesterolaemia gene, how much higher is your cholesterol?

A

5 times

90
Q

What drug aims to lower cholesterol by targeting the intestines?

A

Resins

91
Q

What drug aims to lower cholesterol by targeting the liver?

A

HMG-CoA Reductase Inhibitors (a.k.a Statins)

92
Q

Where does aerobic respiration take place?

A

In mitochondria

93
Q

Where does anaerobic respiration take place?

A

In the cytoplasm

94
Q

Where does skeletal muscle get it’s ATP during light contractions?

A

Oxidative phosphorylation

95
Q

Where does skeletal muscle get it’s ATP during vigorous contractions?

A

Glycolysis and pyruvate is converted to lactate

96
Q

What does the brain use as a source of energy?

A

Glucose

97
Q

What is the only other partial substitute for glucose the brain uses?

A

Ketone bodies

98
Q

What type of respiration does the heart use?

A

Aerobic (completely)

99
Q

What is the normal blood glucose range?

A

4.0-5.5mM

100
Q

What does the liver store?

A

Glycogen

101
Q

When is insulin secreted?

A

When glucose levels rise

102
Q

What does insulin cause?

A

Uptake and use of glucose and storage as glycogen and fat

103
Q

When is glucagon secreted?

A

When glucose levels fall

104
Q

What does glucagon cause?

A

Production of glucose by gluconeogenesis and breakdown of glycogen and fat

105
Q

Where are insulin and glucagon secreted?

A

The islets of the pancreas

106
Q

What is the role of adrenaline?

A

Strong and fast metabolic effects to mobilise glucose for “fight or flight”

107
Q

What is epinephrine?

A

Adrenaline

108
Q

What is the role of glucocorticoids?

A

Steroid hormones which increase synthesis of metabolic enzymes concerned with glucose availability

109
Q

Where are adrenaline and glucocorticoids secreted?

A

The adrenal glands

110
Q

Where is insulin made?

A

In β-cells in islets of Langerhans

111
Q

When you eat what processes occur?

A

Increased blood glucose
Insulin secretion
Increased glucose uptake by the liver for glycogen synthesis and glycolysis
Increased glucose uptake and glycogen synthesis in muscle
Increased triglyceride synthesis in adipose tissue
Increased use of metabolic intermediates throughout the body

112
Q

What happens after a meal when glucose levels begin to fall?

A

Increased glucagon secretion as insulin levels fall
Glucose production from the liver from glycogen breakdown and gluconeogenesis
Fatty acid breakdown as alternative substrate for ATP production

113
Q

What happens after prolonged fasting when glycogen stores are depleted?

A

Glucagon/insulin ratio increases further
Adipose tissue begins to hydrolyse triglyceride to provide fatty acids for metabolism
TCA cycle intermediates are reduced in amount to provide substrate for gluconeogenesis
Protein breakdown provides amino acid substrates for gluconeogenesis
Ketone bodies are produced from fatty acids and amino acids in liver to substitute partially the brain’s requirement for glucose

MCD Year 1 (10 decks)

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