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MCD Metabolism > metabolic pathways and ATP production > Flashcards

metabolic pathways and ATP production Flashcards

glucose metabolism: explain the metabolism of glucose during glycolysis and gluconeogenesis, recall the key reactions in both pathways, and distinguish between the aerobic and anaerobic metabolism of glucose

1
Q

where does glycolysis occur

A

cytoplasm

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2
Q

is glycolysis aerobic or anaerobic

A

anaerobic

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3
Q

give the basic reaction of glycolysis, including ATP and NADH

A

1x6C glucose → 2x3C pyruvate (+2ATP, 2NADH)

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4
Q

what is the production of ATP an example of

A

substrate-level phosphorylation: ATP production by transfer of high energy PO4 3- group from intermediate substrate to ADP

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5
Q

first stage of glycolysis and significance

A

glucose → glucose-6-phosphate + H+ (irreversible; hexokinase (glucokinase in liver); ATP → ADP)

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6
Q

second stage of glycolysis

A

isomerise glucose-6-phosphate to fructose-6-phosphate

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7
Q

third stage of glycolysis and significance of product

A

fructose-6-phosphate → fructose-1,6-bisphosphate (highly symmetrical; phosphofructokinase; ATP → ADP)

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8
Q

in molecular nomenclature, what is the difference between “bi” and “di”

A

“bi” is not joined and “di”is joined

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9
Q

fourth and fifth stages of glycolysis

A

ring opens to form 2x3C; isomerisation to form 2 glyceraldehyde-3-phosphate molecules

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10
Q

sixth stage of glycolysis

A

glyceraldehyde-3-phosphate → 1,3-bisphosphoglycerate (glyceraldehyde-3-phosphate dehydrogenase; NAD+ + Pi → NADH)

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11
Q

seventh stage of glycolysis

A

1,3-bisphosphoglycerate → 3-phosphoglycerate (phosphoglycerate kinase; ADP → ATP)

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12
Q

eighth stage of glycolysis

A

isomerisation of 3-phosphoglycerate to 2-phosphoglycerate (phosphoglycerate mutase)

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13
Q

ninth stage of glycolysis

A

2-phosphoglycerate → phosphoenolpyruvate + H2O (enolase dehydration)

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14
Q

tenth stage of glycolysis

A

phosphoenolpyruvate → pyruvate (pyruvate kinase; ADP → ATP)

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15
Q

what can glucose-6-phosphate be stored as

A

glycogen or pentose phosphates used for nucleotides

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16
Q

what can glycogen be synthesised from

A

UDP-glucose

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17
Q

how are sugars stored

A

glycogen, fatty acids and cholesterol

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18
Q

when are ketone bodies used

A

when the bodt is fasting (used by brain as cannot metabolise fatty acids)

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19
Q

diagram showing generation of molecules from different glycolysis and TCA intermediates

A

diagram form metabolism 9

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20
Q

when does gluconeogenesis occur and what does it prevent

A

when the body is fasting or intense exercise to prevent low [glucose] which could lead to hypoglycaemic coma

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21
Q

short term fasting

A

break down glycogen, release fatty acids from adipose, acetyl CoA converted to ketone bodies (used in muscle to produce glucose)

22
Q

long term (12-18 hours) fasting

A

supplies exhausted

23
Q

define gluconeogenesis

A

produces glucose from non-carbohydrate sources (lactate, amino acids, glycerol)

24
Q

is gluconeogenesis the reversal of glycolysis

A

no - requires different enzymes

25
Q

does gluconeogenesis require ATP

A

yes

26
Q

where does gluconeogenesis occur

A

liver

27
Q

diagram to show gluconeogenesis stages vs glycolysis

A

diagram from metabolism 9

28
Q

what is the common starting point in gluconeogenesis

A

oxaloacetate

29
Q

net loss of gluconeogenesis

A

6 ATP

30
Q

first stage of gluconeogenesis

A

pyruvate → oxaloacetate (pyruvate carboxylase) in mitochondria

31
Q

second stage of gluconeogenesis

A

oxaloacetate → phosphoenolpyruvate (phosphoenolpyruvate carboxykinase) in cytosol; limiting stage

32
Q

third stage of gluconeogenesis

A

phosphoenolpyruvate → G3P → fructose-1,6-bisphosphate

33
Q

fourth stage of gluconeogenesis

A

fructose-1,6-bisphosphate → fructose-6-phosphate (fructose-1,6-bisphosphatase) in cytosol

34
Q

fifth stage of gluconeogenesis

A

fructose-6-phosphate → glucose-6-phosphate

35
Q

sixth stage of gluconeogenesis

A

glucose-6-phosphate → glucose (glucose-6-phosphatase) in cytosol

36
Q

sources of pyruvate

A

lactate (via LDH) and amino acids

37
Q

source of oxaloacetate

A

ketogenic amino acids

38
Q

sources of G3P

A

phosphoenolpyruvate, glycerol → DHAP

39
Q

what happens to ATP and glucose demand in aerobic respiration

A

increase

40
Q

pathways of aerobic metabolism

A

glucose secreted by liver into blood; muscle glycolysis increases (ATP production increases), gluconeogenesis increases (when ATP demand greater than supply), fatty acids increase (more available for B-oxidation)

41
Q

what protein channels are required for cation balance in aerobic metabolism

A

Ca2+ATPase and Na+K+ATPase

42
Q

aerobic pathways diagram

A

diagram from metabolism 9

43
Q

when is anaerobic respiration required

A

when ATP demand is greater than oxidative phosphorylation supply and transport cannot keep up with glucose demand

44
Q

pathways of anaerobic metabolism

A

muscle glycogen breakdown increases; glycolysis rate increases fo pyruvate accumulates and is stored as lactate in muscles; liver uses lactate to form pyruvate via LDH (gluconeogenesis) to be converted to glucose, preventing acidosis

45
Q

anaerobic pathway diagram

A

diagram from metabolism 9

46
Q

3 fates of pyruvate

A

alcoholic fermentation, lactate, generation of acetyl CoA

47
Q

alcoholic fermentation

A

ethanal → ethanol by decarboxylases; produces NAD+ so glycolysis can continue

48
Q

lactate production

A

pyruvate ⇌ lactate via lactate dehydrogenase (LDH), produces NAD+ so glycolysis can continue

49
Q

creatine phosphate metabolism

A

creatine phosphate ⇌ creatine + ATP by creatine kinase

50
Q

high levels of LDH or creatine kinase in plasma

A

tissue and muscle trauma, myocardial infarction

MCD Metabolism (21 decks)

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