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Semester 2 > Metabolism > Flashcards

Metabolism Flashcards

1
Q

What type of receptors does insulin bind to? And which kinase is stimulated which causes translocation of the cytoplasmic vesicle?

A

Insulin tyrosine kinase receptor and protein kinase B

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2
Q

How many moles of ATP are released per mole of glucose in ANAEROBIC respiration

A

2

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3
Q

How does glucagon mobilise hepatic glucose?

A

Binds to GPCR, adenylyl cyclase, ATP-> cAMP, PKA activated.
Directly inhibits glycogen synthase (dec. glycogenesis)
Indirectly activates glycogen phosphorylase (inc. glycogenolysis)

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4
Q

Which protease is mainly responsible for breaking down alveolar walls?

A

Neutrophil elastase

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5
Q

What does UDP stand for?

A

Uridine diphosphate

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6
Q

Which bonds link the backbone of glycogen and which occur at branch points?

A

Backbone - a1-4

Branch point - a1-6

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7
Q

How does glucokinase differ from hexokinase?

A

Glucokinase is not inhibited by high levels of Glc6P so can deal with massive glucose influx after a meal.

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8
Q

Which enzyme terminates the glucagon signal by hydrolysing cAMP to AMP to inactivate PKA. Caffeine and theophylline inhibit this enzyme too.

A

Phosphodiesterase

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9
Q

What effect does adrenaline have when it binds to a-adrenergic GPCRs?

A

Activates phospholipase C -> DAG and IP3-> activate glycogen phosphorylase

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10
Q

Which enzyme is deficient in Type 1a GSD (Von Gierkes)?

A

Glc6Pase

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11
Q

Which enzyme is deficient in Type 2 GSD (Pompes)?

A

Lysosomal acid maltase

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12
Q

What is the other name for the pentode phosphate pathway?

A

Hexose monophosphate shunt

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13
Q

Approximately what percentage of glucose within a RBC is shunted through the PPP?

A

10%

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14
Q

What is the importance of having both NADH and NADPH?

A

Allows different pathways in which they interact to be regulated independently.

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15
Q

What is haemolytic anaemia?

A

A glucose-6-phosphate dehydrogenase deficiency disorder whereby RBCs are destroyed faster than the bone marrow can produce them.

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16
Q

Which enzyme breaks down TGs and VLDLs to release FAs, and where can it be found?

A

Lipoprotein lipase, found in the capillary endothelial cells

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17
Q

What are the three components of the hydrophilic monolayer that surrounds lipoproteins.

A

Cholesterol, apolipoproteins and phospholipids

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18
Q

What do FAs form complexes with in the blood?

A

Albumin

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19
Q

Which carbon atom of a fatty acid is referred to as the alpha carbon?

A

The one in the carboxylic acid group

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20
Q

In which organelle are very long chain fatty aids broken down to long chains?

A

Peroxisomes

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21
Q

What happens to odd-chain fatty acids at the end of oxidation?

A

Left with propionyl-CoA, converted to succinyl-CoA by separate pathway. This can then enter TCA.

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22
Q

What happens in the oxidation of branched chain fatty acids.

A

Undergo a-oxidation whereby alpha carbon is released as CO2, then acetyl -CoA and propionyl-CoA released alternately. (2 then 3 then 2 etc.)

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23
Q

What does MCAD stand for?

A

Medium Chain Acyl-CoA Dehydrogenase

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24
Q

What is the purpose of the PPP?

A

Produce reduced NADPH and pentode phosphates for DNA and RNA

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25
Q

What does CPT stand for in the carnitine shuttle?

A

Carnitine palmitoyl transferase

26
Q

In the TCA cycle, what is inhibited by high ATP and NADH to prevent excess building up?

A

Isocitrate dehydrogenase

27
Q

Where does ketogenesis occur?

A

Mitochondrial matrix

28
Q

What are the three ketone bodies produced?

A

Actetoacetate, acetone and B-hydroxybutyrate

29
Q

Which transporters in the BBB determine the permeability to KBs?

A

MCT1 - monocarboxylic acid transporters

30
Q

What is a reaction that replenishes TCA intermediates called? And name and give the function of a major enzyme in one of these reactions.

A

Anapleurotic reactions, and pyruvate carboxylase, which converts pyruvate to OAA.

31
Q

What is the word for acidic, partially digested food in the gut?

A

Chyme

32
Q

What do bile salts do?

A

Accumulate on surface of lipid droplets to allow pancreatic lipase to hydrolyse the TG

33
Q

What are the epithelial cells of the small intestinal endothelium called?

A

Enterocytes

34
Q

Where is the enzyme lipoprotein lipase found?

A

Surface of capillaries or hepatocytes

35
Q

Why is HDL good for you?

A

Takes excess cholesterol from blood to be destroyed so it doesn’t build up in arteries.

36
Q

What is the regulatory enzyme in cholesterol synthesis?

A

HMG CoA reductase

37
Q

What percentage of bile acids are reabsorbed into the gut for reuse?

A

95%

38
Q

By which process are most large proteins eg lipoproteins taken up into cells?

A

Receptor-mediated endocytosis

39
Q

In what autosomal dominant disorder are LDLr not functional, leading to high risk of CVD?

A

Familial Hypercholesterolaemia

40
Q

On which enzyme do statins act?

A

HMG coa reductase

41
Q

Which four classes of drug are used to treat hyperlipidaemia?

A

Statins, anion exchange resins, vibrates and nicotinic acid

44
Q

What is the most common Urea cycle enzyme deficiency?

A

Ornithine Transcarbamylase deficiency

45
Q

Which amino acids are a-ketoglutarate, pyruvate and oxaloacetate each associated with?

A

a-ketoglutarate - glutamate
Pyruvate - alanine
Oxaloacetate - Aspartate

46
Q

What does NAD stand for?

A

Nicotinamide adenine dinucleotide

47
Q

How many molecules of ATP are used (net loss) in the Cori cycle?

A

4 (2 in, 6 used)

48
Q

The metabolism of which three amino acids are affected in maple syrup urine disease? And which enzyme is missing?

A

Valine, lucine and isoleucine, and a-ketoacid dehydrogenase

49
Q

Which enzyme is deficient in phenylketonuria? And what can this disease cause?

A

Phenylalanine hydroxylase, and severe mental retardation

50
Q

What do caffeine and theophylline inhibit and why does this make you more alert?

A

Phosphodiesterase which stimulates glycogenolysis giving more glucose.

51
Q

Which part of the pancreas is insulin released from?

A

B cells of the islets of Langerhan’s

52
Q

What pH is the chyme that leaves the stomach?

A

pH 4

53
Q

What are the two constituents of bile?

A

Phospholipids and bile salts

54
Q

Name three things that essential FA deficiency can lead to

A

Hair loss, poor wound healing, scaling dermatitis, stunted growth, renal failure

55
Q

How do trans double bonds affect melting point, in comparison with cis?

A

Increase as they can get closer together

56
Q

What are the main symptoms of Pompe’s disease?

A

Respiratory muscle weakness (leading to tiredness) and proximal muscle weakness (pelvic and shoulder)

57
Q

What does the lack of acid maltase in Pompes lead to?

A

Build up of glycogen in lysosomes in muscle cells

58
Q

In enzyme replacement therapy, which enzyme is used as an analogue of acid maltase?

A

Alglucosidase-alpha (myozyme)

59
Q

What are three reasons why transamination of AAs is necessary?

A

Degradation of AAs
Synthesis of non-essential AAs
Exchange of amino groups between AAs

60
Q

Which enzyme is defected in alkaptonuria?

A

Homogentisate oxidase

61
Q

Why is urine black in alkaptonuria?

A

Homogentisic acid is not broken down and instead oxidises on standing which causes it to become a black colour.

62
Q

Which enzyme is defected in albinism?

A

Tyrosinase

Semester 2 (6 decks)

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