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biochem 501 > Unit 4 exam > Flashcards

Unit 4 exam Flashcards

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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
cholesterol facts
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
26
what are lipoproteins
lipid/protein hybrids that carry cholesterol and other lipids
27
what are chylomicrons
largest and least dense lipoprotein carry dietary fat to tissues
28
what is ULDL
lipoprotein that transports TAG to adipose and muscle tissues, removal of TAG forms LDL
29
what is LDL
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
what is apolipoprotein
a protein embedded in phospholipid monolayer of lipoproteins
31
what are statins
pharmaceuticals that attenuate to cholesterol synthesis pathway
32
what is HMG-CoA reductase
an enzyme used in phase 1 of cholesterol synthesis where mevalonate is synthesized from acetyl CoA
33
what are the methods of regulation for interconverting fructose-6Pi and fructose 1-6bisPi
- 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
what other function is occurring in the liver along with ketogenesis
gluconeogenesis
35
what does ApoB do
interacts with LDL receptor to stimulate endocytosis of LDL particle
36
what is the substrate for fatty acid synthesis
malonyl CoA
37
What compound is derived from amino acids and a major donor of methyl groups
S-Adenosylmethionine (SAM)
38
characteristics of fatty acid synthesis in animal cells
-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
if a person cannot use the oxidative phase of PPP, how can they generate ribose-S-Pi
through reverse of non-oxidative phases with intermediates from glycolysis
40
characteristics of ribonuclease reductase
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
what is biotin
a cofactor of carboxylases
42
what are aicosanoids
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
what is insulin
stimulates conversion of dietary carbohydrates into TAGs
44
what happens 48 hours after fasting
glucagon mediated inactivation of F.A. synthesis by phosphorylation
45
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
1. active, inhibited 2. inhibited, active 3. active, inhibited 4. inhibited, active
46
receptor signaling
-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
what does tyrosine kinase do?
phosphorylates a tyrosine molecule
48
what happens when GPCR can't hydrolyze GTP to GDP
glycogenolysis increases bc increase in signaling cascade
49
what process has a high energy cost and a compound that cannot be synthesized from acetyl CoA
pyruvate into glucose, glucose can't be synthesized from acetyl CoA
50
what are the effects of high levels of ATP and citrate in a cell
inhibition of catabolic pathways like glycolysis and they provide energy and substrates for anabolic pathways
51
relationship between glucose 6 Pi dehydrogenase and malaria
decrease in the enzyme protects from malaria because people with the deficiency and the parasite are more sensitive to reactive oxygen species
52
if molecules for F.A. synthesis are not available, where can we get them
stimulate oxidative phase of pentose Pi pathway to get NADH and nonoxidative pathway to get glycolytic intermediates to generate ATP
53
what would a drug prescribed to prediabetics do?
increase insulin release by binding ATP gated K+ channels and decreasing the transport of K+ out of pancreatic beta cells
54
what are fatty acids and cholesterol synthesized from
acetyl CoA
55
fatty acid synthesis pathway
form malonyl ACP-->condensation-->dehydration-->reduction of carbonyl-->reduction of double bond-->condensation
56
what are lower Kt values correlated with
higher blood glucose because slower glucose transport
57
what prostaglandin inhibiting compounds should pregnant women avoid
NSAIDs
58
what is the active form of biotin
activated when carrying carbon dioxide
59
where are TAGs produced
adipose tissue
60
what is glutathione
a metabolite derived from amino acids and a reducing agent that helps remove toxic peroxides from cells
61
what does ribonucleic reductase do
catalyzes the conversion of ribonucleoside diphosphates to dADP (ADP-->dADP)
62
what do increased levels of cAMP do
activate PKA to increase fuel mobilization and energy production
63
before breaking fast what process is active
glyconeogenesis in the liver
64
what do decreased levels of cAMP do
glycogenolysis decreases
65
glucagon signaling causes a decrease in levels of fructose 2-6 phosphate which does what
activates fructose 16 bisphoatase leading to gluconeogenesis
66
how much atp is required to synthesize glucose from glucose 6Pi, fructose 16 pPi or dihydroxy acetone Pi
0 atp

biochem 501 (4 decks)

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