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biochem 501 > Unit 4 exam > Flashcards

Unit 4 exam Flashcards

1
Q

what triggers insulin release in the cell

A

potassium channels being closed by increased intracellular ATP

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2
Q

what is glucagon

A

protein released at low blood glucose, binds receptors on fat and liver cells to increase blood glucose, high levels stimulate gluconeogenesis

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3
Q

what is epinephrine

A

a small molecule released during exercise/stress

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4
Q

what is leptin

A

a protein that is released after a meal, an appetite suppressor
stimulates uncoupling protein 1 increasing ATP production in fat cells

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5
Q

what are carbohydrates

A

aldehydes/ketones with at least 2 hydroxyl groups

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6
Q

what are monosaccharides

A

the simplest carb
ex: glucose

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7
Q

what are disaccharides

A

next simplest carb
ex: fructose

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8
Q

what are polysaccharides

A

sugars with 10^7 monosaccharide units
ex: cellulose and glycogen

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9
Q

what does the pancreas do

A

senses fasting state and releases glucagon

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10
Q

what does the liver do

A

receives glucagon and starts glycogenolysis to release glucose, gluconeogenisis to produce glucose and ketogenesis to produce ketones

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11
Q

what does the adipose tissue do

A

receives glucagon and starts lipolysis to release fatty acids and glycerol

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12
Q

what is the difference between glycogen breakdown in the muscle vs in the liver

A

in the liver it replenishes low blood glucose
in the muscle it provides energy for the muscle

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13
Q

what does a kinase do

A

transfers phosphate from a triphosphate to an acceptor molecule

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14
Q

what are the fasting pathways

A

glucagon–>fat cells–>1 TAG–>3 F.A.+glycerol–>liver
glucagon–>liver–>glycogen–>glucose–>–>blood glucose

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15
Q

what are the exercise pathways

A

epinephrine–>fat–>1TAG–>3F.A.–>glycerol–>liver
epinephrine–>liver–>glycogen–>glucose–>–>blood glucose
epinephrine–>muscle–>glycogen–>glucose-1P–>glucose-6P–>pyruvate–>H2O+CO2 and lactate

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16
Q

what are the symptoms of a type 1 diabetic

A

patient loses weight because not using glucose
ketone bodies build up which lowers blood glucose
breath smells like alcohol because acetone that is not used is exhaled

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17
Q

how do enzyme linked receptors become activated

A

they require autophosphorylation

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18
Q

characteristics of gluconeogenesis in liver

A

-uses C skeletons derived from glucogenic amino acids to start synthesis
-employs phosphatase enzyme to convert glucose6P to glucose
-it is one way that mammals maintain normal blood glucose while fasting
-glucogenic amino acid catabolism results in citric acid cycle intermediates and can be used to synthesize glucose in gluconeogenesis
-the majority of the steps occur in the cytosol
-glycolysis and gluconeogenesis is reciprocally regulated (1 on 1 off)

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19
Q

characteristics of glycogen metabolism

A

glycogen synthesis occurs mainly in liver and muscle
enzyme responsible for glucose 6Pi–>glucose is not expressed in muscle cells
liver glycogen is mostly gone after first 24 hours of fasting

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20
Q

what are the bypasses

A

pyruvate–>oxaloacetate(OAA) inside mitochondria (biotin cofactor)
OAA as malate transported to cytoplasm
hydrolysis reactions release phosphate catalyzed by phosphatase

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21
Q

what is the net ATP produced in muscle during glycolysis of glucose

A

3

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22
Q

what enzyme is deficient in populations exposed to malaria

A

glucose 6Pi dehydrogenase

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23
Q

what system is most active after eating a sugar cookie

A

fatty acid synthesis

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24
Q

order of synthesis of TAG

A

glucose–>acetyl CoA–>malonyl CoA–>phosphatidic acid–>TAG

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25
Q

cholesterol facts

A

18 acetyl CoA–>1 cholesterol
some incorporated in membrane of liver cells
some converted to oxysterol
most exported as bile acids, steroid hormones, or cholesterol esters
involved in steroid hormone synthesis

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26
Q

what are lipoproteins

A

lipid/protein hybrids that carry cholesterol and other lipids

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27
Q

what are chylomicrons

A

largest and least dense lipoprotein
carry dietary fat to tissues

28
Q

what is ULDL

A

lipoprotein that transports TAG to adipose and muscle tissues, removal of TAG forms LDL

29
Q

what is LDL

A

lipoprotein that delivers cholesterol–>muscle and adipose tissue, excess can be taken up by macrophages forming foam cells leading to plaque build up and cardiovascular disease

30
Q

what is apolipoprotein

A

a protein embedded in phospholipid monolayer of lipoproteins

31
Q

what are statins

A

pharmaceuticals that attenuate to cholesterol synthesis pathway

32
Q

what is HMG-CoA reductase

A

an enzyme used in phase 1 of cholesterol synthesis where mevalonate is synthesized from acetyl CoA

33
Q

what are the methods of regulation for interconverting fructose-6Pi and fructose 1-6bisPi

A
  • fructose 2-6 bisPi activates phosphofructokinase 1
  • fructose 2-6 bisPi inhibits fructose 1-6 bisphosphotase
    -phosphofructokinase-2 catalyzes phosphorylation of fructose 6Pi forming fructose 2-6bisPi
34
Q

what other function is occurring in the liver along with ketogenesis

A

gluconeogenesis

35
Q

what does ApoB do

A

interacts with LDL receptor to stimulate endocytosis of LDL particle

36
Q

what is the substrate for fatty acid synthesis

A

malonyl CoA

37
Q

What compound is derived from amino acids and a major donor of methyl groups

A

S-Adenosylmethionine (SAM)

38
Q

characteristics of fatty acid synthesis in animal cells

A

-NADPH is produced in cytosol by pentose phosphate pathway
-malonyl CoA is formed in cytosol
-acetyl CoA transported out of mitochondrion in form of citrate on citrate shuttle
-pyruvate is transported across mitochondrial membrane

39
Q

if a person cannot use the oxidative phase of PPP, how can they generate ribose-S-Pi

A

through reverse of non-oxidative phases with intermediates from glycolysis

40
Q

characteristics of ribonuclease reductase

A

dATP is a negative allosteric effector
acts on nucleoside diphosphates
ATP is a positive allosteric effector
hydroxyurea can be used as cancer treatment because it inhibits the enzyme

41
Q

what is biotin

A

a cofactor of carboxylases

42
Q

what are aicosanoids

A

phospholipase A2 catalyzes the release of arachidonate from phospholipids
include prostaglandins, leukortrienes, and thrombaxnes
aspirin inhipids COX enzymes by acetylation of serine in active sites
NSAIDs like ibuprofen inhibit COX enzymes as competitive inhibitors

43
Q

what is insulin

A

stimulates conversion of dietary carbohydrates into TAGs

44
Q

what happens 48 hours after fasting

A

glucagon mediated inactivation of F.A. synthesis by phosphorylation

45
Q

what are the states of energy storage and blood glucose replenishment in:
-glucose uptake by adipose and muscle tissues
-gluconeogenesis
glycogen synthesis F.A. synthesis
-glycogen breakdown F.A. breakdown

A
  1. active, inhibited
  2. inhibited, active
  3. active, inhibited
  4. inhibited, active
46
Q

receptor signaling

A

-ligand modulating ion transport like ATP binds to membrane bound receptor resulting in signaling cascade to modulate gene expression
-ligand stimulating fuel molecule storage like insulin binds to membrane bound receptor resulting in signaling cascade to modulate gene expression
-ligand stimulating fuel molecules like glucagon bind to membrane bound receptor resulting in signaling cascade that can replenish low blood glucose

47
Q

what does tyrosine kinase do?

A

phosphorylates a tyrosine molecule

48
Q

what happens when GPCR can’t hydrolyze GTP to GDP

A

glycogenolysis increases bc increase in signaling cascade

49
Q

what process has a high energy cost and a compound that cannot be synthesized from acetyl CoA

A

pyruvate into glucose, glucose can’t be synthesized from acetyl CoA

50
Q

what are the effects of high levels of ATP and citrate in a cell

A

inhibition of catabolic pathways like glycolysis and they provide energy and substrates for anabolic pathways

51
Q

relationship between glucose 6 Pi dehydrogenase and malaria

A

decrease in the enzyme protects from malaria because people with the deficiency and the parasite are more sensitive to reactive oxygen species

52
Q

if molecules for F.A. synthesis are not available, where can we get them

A

stimulate oxidative phase of pentose Pi pathway to get NADH and nonoxidative pathway to get glycolytic intermediates to generate ATP

53
Q

what would a drug prescribed to prediabetics do?

A

increase insulin release by binding ATP gated K+ channels and decreasing the transport of K+ out of pancreatic beta cells

54
Q

what are fatty acids and cholesterol synthesized from

A

acetyl CoA

55
Q

fatty acid synthesis pathway

A

form malonyl ACP–>condensation–>dehydration–>reduction of carbonyl–>reduction of double bond–>condensation

56
Q

what are lower Kt values correlated with

A

higher blood glucose because slower glucose transport

57
Q

what prostaglandin inhibiting compounds should pregnant women avoid

A

NSAIDs

58
Q

what is the active form of biotin

A

activated when carrying carbon dioxide

59
Q

where are TAGs produced

A

adipose tissue

60
Q

what is glutathione

A

a metabolite derived from amino acids and a reducing agent that helps remove toxic peroxides from cells

61
Q

what does ribonucleic reductase do

A

catalyzes the conversion of ribonucleoside diphosphates to dADP (ADP–>dADP)

62
Q

what do increased levels of cAMP do

A

activate PKA to increase fuel mobilization and energy production

63
Q

before breaking fast what process is active

A

glyconeogenesis in the liver

64
Q

what do decreased levels of cAMP do

A

glycogenolysis decreases

65
Q

glucagon signaling causes a decrease in levels of fructose 2-6 phosphate which does what

A

activates fructose 16 bisphoatase leading to gluconeogenesis

66
Q

how much atp is required to synthesize glucose from glucose 6Pi, fructose 16 pPi or dihydroxy acetone Pi

A

0 atp

biochem 501 (4 decks)

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