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Flashcards in metabolism Deck (91):
1

metab that occurs in mito

fatty acid BETA-ox.
acetyl co-A prod.
TCA cycle.
ox phos.

2

metab that occurs in cytoplasm

glycolysis.
FA synth.
HMP shunt.
protein synth (RER).
steroid synth (SER).

3

metab that occurs in both mito and cyto

Heme synth.
Urea cycle.
Gluconeogenesis.

HUGS take two.

4

kinase

use ATP to add high-energy phosphate onto substrate

5

phosphorylase

adds inorganic phosphate onto substrate without using ATP

6

phosphatase

removes phosphate group from substrate

7

dehydrogenase

oxidizes substrate

8

carboxylase

transfers CO2 groups with help of BIOTIN

9

rate-determining enzyme: glycolysis

phosphofructokinase-1

10

rate-determining enzyme: gluconeogenesis

fructose-1,6-bisphosphatase

11

rate-determining enzyme: TCA cycle

isocitrate dehydrogenase

12

rate-determining enzyme: glycogen synthesis

glycogen synthase

13

rate-determining enzyme: glycogenolysis

glycogen phosphorylase

14

rate-determining enzyme: HMP shunt

glucose-6-phosphate dehydrogenase

15

rate-determining enzyme: de novo pyrimidine synth

carbamoyl phosphate synthetase II

16

rate-determining enzyme: de novo purine synth

glutamine-PRPP amidotransferase

17

rate-determining enzyme: urea cycle

carbamoyl phosphate synthetase I

18

rate-determining enzyme: fatty acid synth

acetyl-coA carboxylase (ACC)

19

rate-determining enzyme: fatty acid oxidation

carnitine acyltransferase 1

20

rate-determining enzyme: ketogenesis

HMG-CoA synthase

21

rate-determining enzyme: chol synth

HMG-CoA reductase

22

aerobic metab of glucose produces?

32 ATP: malate-aspartate shuttle in heart, liver.

30 ATP: glycerol-3-phosphate shuttle in muscle.

23

anaerobic glycolysis produces?

2 net ATP per glucose molec

24

activated carrier of phosphoryl

ATP

25

activated carrier of electrons

NADH.
NADPH.
FADH2.

26

activated carrier of acyl

coenzyme A.
lipoamide.

27

activated carrier of CO2

biotin

28

activated carrier of 1 carbon units

tetrahydrofolate

29

activated carrier of CH3 groups

SAM

30

activated carrier of aldehydes

TPP (thiamine pyrophosphate, B1)

31

universal electron acceptor: NAD+

nicotinamide.
from vit B3.

used in catabolic processes to carry reducing equivalents away as NADH.

32

universal electron acceptor: NADP+

nicotinamide.
NADPH made in HMP SHUNT.
used in anabolic processes as a SUPPLY of reducing equivalents.

33

universal electron acceptor: FAD+

flavin nucleotides.
from vit B2.

34

processes that use NADPH

1. anabolic processes: steroid and FA synth.
2. respiratory burst.
3. P450.
4. glutathione reductase.

35

hexokinase/glucokinase

phosphorylate glucose to yield GLUCOSE-6-PHOSPHATE.

1st step of glycolysis AND glycogen synth in liver, depending on enz location.

36

hexokinase

UBIQUITOUS.
high affinity (low Km).
low capacity (low Vmax).
NOT induced by insulin.

37

what inhibits hexokinase?

glucose 6-phosphate via feedback inhib

38

glucokinase

LIVER and BETA CELLS of pancreas.
low affinity (high Km).
high capacity (high Vmax).
induced by insulin.

39

what does glucokinase with excess glucose?

phosphorylates it (after a meal) to SEQUESTER it in the liver - liver serves as blood glucose buffer

40

which steps in glycolysis require ATP?

1. hexo/glucokinase.
2. phosphofructokinase-1.

41

what inhibits glucokinase?

fructose-6-phosphate

42

what inhibits PFK1?

ATP.
citrate.

43

what stimulates PFK1?

AMP.
fructose 2,6-bisphosphate.

44

which steps in glycolysis produce ATP?

1. phosphoglycerate kinase.
2. pyruvate kinase.

45

what inhibits PK?

ATP.
alanine.

46

what stimulates PK?

fructose 1,6-bisphosphate

47

fructose bisphosphatase 2

active in FASTING state:
increase glucagon = cAMP = protein kinase A = increase fructose bisphosphatase 2.

F26BP to F6P for gluconeogenesis.
decrease PFK2 = less glycolysis.

48

phosphofructokinase-2

active in FED state:
increase insulin = decrease cAMP = decrease protein kinase A = increase PFK2.

F26BP stimulates PFK1 for more glycolysis.
decrease fructose bisphosphatase 2.

49

pyruvate dehydrogenase complex RXN

pyruvate + NAD+ + CoA =
acetyl coA + CO2 + NADH

50

pyruvate dehydrogenase complex COFACTORS

1. TPP (B1)
2. FAD (B2)
3. NAD (B3)
4. CoA (B5)
5. lipoic acid

51

what activates pyruvate dehydrogenase complex?

exercise:
increased NAD+/NADH ratio.
increased ADP.
increased Calcium.

52

what other complex is similar to pyruvate dehydrogenase complex?

alpha-ketoglutarate dehydrogenase complex in TCA cycle. same cofactors, similar substrate.

alpha-KG --> succinyl CoA.

53

what inhibits lipoic acid?

arsenic - cause vomiting, pain, rice water stools, garlic breath, delirium.

54

TX of arsenic poisoning

dimercaprol (chelator) to displace arsenic ions

55

pyruvate dehydrogenase deficiency

back up of substrate (pyruvate, alanine).

increased LDH activity to regenerate NAD+ causes LACTIC ACIDOSIS.

can be congenital or
acquired (alcoholics, B1 def).

56

findings in pyruvate dehydrogenase deficiency

neuro defects

57

TX of pyruvate dehydrogenase deficiency

increased intake of KETOGENIC nutrients-
high fat content or
increased Lysine and Leucine (the only purely ketogenic AAs)

58

pyruvate can be metabolized into:

1. alanine.
2. oxaloacetate.
3. acetyl CoA.
4. lactate.

59

function of alanine from pyruvate

carries amino groups from muscle TO LIVER

60

function of oxaloacetate from pyruvate

replenish TCA cycle or
used in gluconeogenesis

61

function of acetyl CoA from pyruvate

transition from glycolysis to TCA

62

function of lactate from pyruvate

end of anaerobic glycolysis

63

which organs use anaerobic glycolysis (and thus produce lactate)?

RBCs.
leukocytes.
kidney medula.
testes.
lenses.
cornea.

64

what inhibits pyruvate dehydrogenase?

ATP.
acetyl CoA.
NADH.

65

irreversible enzymes in TCA

1. pyruvate dehydrogenase.
2. citrate synthase.
3. isocitrate dehydrogenase.
4. alpha-ketoglutarate dehydrogenase.

66

intermediates in TCA (in order)

Citrate.
Isocitrate.
alpha-Ketoglutarate.
Succinyl CoA.
Succinate.
Fumarate.
Malate.
Oxaloacetate.

"Citrate Is Kreb's Starting Substrate For Making Oxaloacetate"

67

NADH electrons enter mito...

via malate-aspartate
or glycerol-3-phosphate shuttle.

68

where does FADH2 enter ETC/oxphos?

complex II (at lower energy level than NADH)

69

ATP produced by ATP synthase

using proton gradient formed in intermembranous space.

1 NADH = 3 ATP.
1 FADH2 = 2 ATP.

70

ox phos poison: electron transport inhibitors

directly inhibit ETC, causing decreased proton gradient and block of ATP synth.

1. rotenone.
2. CN-
3. antimycin A.
4. CO

71

ox phos poison: ATP synthase inhibitors

directly inhibit mito ATP synthase, causing increased proton gradient.

NO ATP IS PRODUCED bc electron transport stops.

drug: oligomycin

72

ox phos poison: uncoupling agents

increase permeability of membrane, causing decreased proton gradient and increased O2 consumption.

ATP synth stops but ETC continues.
produces heat.

1. 2,4-dinitrophenol.
2. aspirin (overdose).
3. thermogenin (brown fat).

73

gluconeogenesis occurs in?

LIVER.
enzymes also found in kidney, intestinal epith.

74

gluconeogenesis irreversible enzymes

Pyruvate carboxylase.
PEP carboxykinase.
Fructose-1,6-bisphosphatase.
Glucose-6-phosphatase.

"Pathway Produces Fresh Glucose"

75

deficiency of gluconeogenesis enzymes leads to?

hypoglycemia

76

why cant MUSCLE participate in gluconeogenesis?

it lacks glucose-6-phosphatase

77

what type of FA can also contribute to gluconeogenesis?

odd-chain FA: yield 1 propionyl CoA during metabolism, which can enter TCA as succinyl CoA and undergo gluconeogenesis.

*even-chain FAs only yield acetyl CoA equivalents

78

pyruvate carboxylase

in mito.
pyruvate to oxaloacetate.
requires biotin, ATP.
activated by acetyl CoA.

79

PEP carboxykinase

in cytosol.
oxaloacetate to PEP.
requires GTP.

80

fructose-1,6-bisphosphatase

in cytosol.
fructose-1,6-bisphosphate to fructose-6-phosphate.

81

glucose-6-phosphatase

in ER.
glucose-6-phosphate to glucose.

82

HMP shunt

key role: provide NADPH from abundant G6P supply.

aka pentose phosphate pathway.

83

phases of HMP shunt

1. oxidative (irreversible).
2. nonoxidative (reversible).

84

products of HMP shunt

1. NADPH.
2. ribose.
3. glycolytic intermediates (G3P, F6P).

85

sites of HMP shunt

CYTOPLASM-
lactating mammary glands.
liver, adrenal cortex (FA/steroid synth).
RBCs (glutathione reduction).

86

ATP in HMP shunt

none used or produced

87

oxidative rxn of HMP shunt

glucose 6-phosphate
yields 2 NADPH, CO2, ribulose-5P
(multiple in-between steps)
via G6P dehydrogenase.

*RATE-LIMITING STEP

88

nonoxidative rxn of HMP shunt

ribulose-5P (from oxidative phase)
yields ribose-5P, G3P, F6P
(multiple in-between steps)
via transketolase with B1 cofactor.

89

what enz is activated in respiratory (oxidative) burst?

NADPH oxidase -
membrane bound.
in neutrophils, monocytes.

*NADPH involved in ROI production and neutralization

90

role of resp burst

immune response: rapid release of reactive oxygen intermediates (ROIs)

91

sequence of enzymes in ROI prod

NADPH oxidase.
superoxide dismutase.
myeloperoxidase OR catalase/glutathione peroxidase