B2.043 Metabolism and its Regulation Pt. 2 Flashcards Preview

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Flashcards in B2.043 Metabolism and its Regulation Pt. 2 Deck (39)
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1

how can metabolic plasticity be altered?

suppressed by over consumption of food
lost in type 1 diabetes

2

what mechanisms maintain caloric homeostasis in the fed state?

glycogenesis
glycolysis
lipogenesis

3

what mechanism maintain caloric homeostasis in the fasted state?

glycogenolysis
gluconeogenesis
lipolysis
fatty acid oxidation
ketogenesis

4

what are the 4 primary mechanisms for switching between fed and starved states?

substrate supply
allosteric effectors
covalent modification
induction repression of enzymes

5

what substrate is necessary for glycogenesis and lipogensis?

dietary glucose

6

what substrate is required for ketone body synthesis by the liver?

high serum fatty acid concentration

7

what substrates must be available for protein synthesis?

all 20 AAs

8

when can the brain use ketone bodies?

when blood concentration is high
about 48 hours starved

9

what are the 3 primary substrates involved in allosterically affecting the fed state?

glucose
fructose 2,6-P2
Malonyl-CoA

10

what enzymes does glucose allosterically affect?

inhibits glycogen phosphorylase
stimulates glycogen synthase
stimulates glucokinase

11

what enzymes does fructose 2,6-P2 allosterically affect?

inhibits fructose 1,6 bisphosphatase
stimulates phosphofructo-1-kinase (PFK1)

12

what enzyme does malonyl-CoA allosterically affect?

inhibits carnitine palmitoyl coA transferase 1 (CPT1)

13

what is CPT1?

rate limiting enzyme in oxidation of fatty acids
inhibited in fed state bc don't want fats you just made to be broken down immediately

14

what substrate is required to transport long chain fatty acids into the mitochondrial matrix space?

carnitine

15

where does fatty acid oxidation occur?

mitochondrial matrix space

16

what are the 2 primary substrates involved in allosterically regulating the fasted state?

long chain acyl coA
acetyl coA

17

what enzyme does long chain acyl CoA allosterically affect?

inhibits acetyl CoA carboxylase to prevent fat production

18

what enzymes does acetyl CoA allosterically affect?

inhibits pyruvate dehydrogenase (makes pyruvate)
stimulates pyruvate carboxylase (makes oxaloacetate and eventually glucose)

19

what is the primary covalent modification that affects switching between fed and starved states?

phosphorylation
nonphosphorylated = fed
phosphorylated = starved

20

high insulin
low glucagon
low cAMP
low PKA activity

fed state

21

low insulin
high glucagon
high cAMP
high PKA

starved state

22

what are the rate limiting enzymes impacted by induction-repression pathways in the fed state?

glucokinase- glycolysis
G6P dehydrogenase -pentose phosphate
acetyl-CoA carboxylase- fatty acid synthesis

23

in the well fed state, what enzyme accounts for 10% of total liver enzymes?

fatty acid synthase

24

what transcription factors does insulin act on?

inhibits forkhead transcription factor
stimulates SREBP-1

25

what transcription factor does glucagon act on?

CREB

26

what are the 2 rate limiting enzymes impacted by induction-repression pathways in the fed state?

glucose 6 phosphatase
PEP carboxykinase (only subject to regulation by transcription)

27

what is hexokinase 4?

glucokinase
glucose sensor in the liver

28

what makes glucokinase different from the other hexokinases?

higher Km
allows glucokinase to sense and respond immediately to the glucose concentration in the blood

29

what is fructose 2,6-bisphosphate?

master regulator of glycolysis and gluconeogenesis in the liver
promotes glycolysis
inhibits gluconeogenesis

30

how is fructose 2,6-bisphosphate made?

made from fructose 6-phosphate by a kinase
converted back to fructose 6-phosphate by a phosphatase
kinase and phosphatase located on same bifunctional enzyme