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PCS > Unit 3 - Mobilisation of Energy > Flashcards

Unit 3 - Mobilisation of Energy Flashcards

1
Q

describe the process of mobilisation of lipids induced by hormones

A

adrenaline/ glucagon bind to a GPCR
- this activates adenylate cyclase - cAMP -PKA activates lipases that break down TAG into DAG into MAG which then become fatty acid and glycerol

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2
Q

how are fatty acids and glycerol used?

A

fatty acid - activated/ oxidised

glycerol - glycolysis

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3
Q

what are fatty acids attached to in the blood?

A

albumin

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4
Q

which enzyme is needed for fatty acid activation?

A

acyl coA synthetase = thiokinase

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5
Q

how does fatty acid activation happen

A

ATP + fatty acid forms acyl-adenylate intermediate which then binds with coA and forms acyl coA + AMP

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6
Q

where are short/medium chain fatty acids activated?

A

within mitochondrion

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7
Q

where are long chain fatty acids activated?

A

in cytoplasm

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8
Q

how is acyl coA from long chain fatty acids transported into the mitochondrion?

A

via carnitine shuttle

  • acyl coA transferred onto carnitine via CPT1
  • translocase transfers acyl carnitine into mitochondrion
  • acyl coA regenerated by CPT2 - releasing free carnitine
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9
Q

what are the four steps of oxidation of beta carbon

A

oxidation, hydration, oxidation, hydrolysis

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10
Q

which enzyme cleaves the alpha and beta carbon of the fatty acid? what products are produced?

A

enzyme: thiolase

produces acetyl coA + acyl coA (with 2 fewer carbons)+ NADH + FADH2

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11
Q

how are the products of beta oxidation used?

A

acetyl coA - fed into TCA cycle

FADH/ NADH2 - directly into electron transport chain

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12
Q

what structure are lipids transported in?

A

lipoproteins - chylomicrons, VLDL, LDL & HDL

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13
Q

what do lipoproteins contain?

A

TAG, cholesterol, phospholipids, apolipoproteins

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14
Q

what do VLDL and chylomicrons transport?

A

lipoproteins rich in TAG to cells via lipoprotein lipase

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15
Q

what does VLDL become?

A

after stripping TAG becomes more dense so remodelled in liver into LDL which delivers cholesterol to the cells

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16
Q

what is cholesterol used for?

A

used in membranes or synthesis of steroid hormones

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17
Q

what is the role of HDL?

A

brings excess cholesterol from cells to liver (reverse cholesterol transport)

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18
Q

what is the term for liver excreting excess cholesterol as bile or bile salts?

A

hypercholesterolaemia

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19
Q

what process allows uptake of VLDL and LDL into liver?

A

receptor mediated endocytosis

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20
Q

how do chylomicrons remnant contribute to atheroscelerosis?

A

pass into epithelial lining and become oxidised - then taken up by macrophages which become foam cells and increase plaque in arteries

21
Q

what two molecules are needed to begin the synthesis of cholesterol?

A

acetoacetyl CoA + Acetyl CoA

22
Q

explain the synthesis of cholesterol

A

acetoacetyl CoA + Acetyl CoA = mevalonate (catalysed by HMG CoA reductase - requires NADPH)
mevalonate - squalene - cholesterol

23
Q

how do statins inhibit the synthesis of cholesterol?

A

target mevalonate synthesis by inhibiting HMG CoA reductase

24
Q

what enzyme catalyses the conversion of glucose 6P to glucose 1P?

A

phoshoglucomutase

25
Q

what enzyme catalyses the conversion of glucose 1P to UDP-glucose?

A

UDP-glucose pyrophosphorylase

26
Q

what enzyme catalyses the conversion of UDP-glucose to glycogen?

A

glycogen synthase

27
Q

summarise the process of glycogenesis?

A

glucose 6P - glucose 1P - UDP glucose - glycogen

28
Q

how is glycogen elongated once it reaches 8 residues?

A

glycogen branching enzymes transfer onto 1-6 glycosidic bonds

29
Q

what enzyme catalyses the conversion of glycogen to glucose 1-P?

A

glycogen phosphorylase

30
Q

what enzyme catalyses the conversion of glucose1P to glucose-6P?

A

phosphoglucomutase

31
Q

what enzyme catalyses the conversion of glucose 6P to glucose?

A

glucose 6 phosphatase

32
Q

summarise the process of glycogenolysis

A

glycogen - glucose 1P - glucose 6P - glucose

33
Q

what is the role of the debranching enzyme in glycogenolysis?

A

moves 1-6 branches to end of 1-4 chain so that phosphorylase can continue

34
Q

how does glucagon activate glycogenolysis?

A

GPCR - adenylate cyclase - cAMP - PKA

PKA deactivates glycogen synthase and activates phosphorylase kinase which activates glycogen phosphorylase

35
Q

how does glucagon activate gluconeogenesis?

A

activates PKA which activates FBPase 2 - fructose 2,6BP -to fructose 6P

36
Q

which four enzymes in gluconeogenesis can overcome the irreversible reactions of glycolysis?

A
  • PC = pyruvate carboxylase
  • PEPCK - bypasses pyruvate kinase
  • Fru 1,6 BPase - bypasses PFK
  • Glc 1,6 BPase - bypasses glucokinase
37
Q

which enzyme catalyses the conversion of lactate to pyruvate?

A

lactate dehydrogenase

38
Q

which enzyme catalyses the conversion of pyruvate to oxaloacetate?

A

pyruvate carboxylase

39
Q

which enzyme catalyses the conversion of oxaloacetate to malate?

A

malate dehydrogenase

40
Q

which enzyme catalyses the conversion of oxaloacetate to PEP?

A

PEPCK (using GTP)

41
Q

summarise the steps to convert pyruvate to PEP?

A

pyruvate - oxaloacetate - malate - oxaloacetate - PEP

42
Q

which enzyme catalyses the conversion of Fru1,6 BP to Fru 6P?

A

Fru 1,6 BPase

43
Q

which enzyme catalyses the conversion of Fru 6P to glucose 6P?

A

phosphoglucose isomerase

44
Q

which enzyme catalyses the conversion of glucose 6P to glucose?

A

glucose 6Pase

45
Q

summarise the conversion of PEP to glucose

A
  • glycolysis proceeds backwards so PEP eventually converted into Fru 1,6 BP - Fru 6P - Glu 6P - Glucose
46
Q

how can alanine be used for gluconeogenesis

A

converted into pyruvate via alanine transaminase

47
Q

how can amino acids be used for gluconeogenesis?

A

converted into TCA cycle intermediates then to malate - oxaloacetate - PEP

48
Q

how can glycerol be used for gluconeogenesis?

A

converted into glycerol 3P (glycerol kinase) - fru 1,6 BP - fru 6P - glc 6P - glucose

PCS (29 decks)

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