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PBL > Biochem 22 HY > Flashcards

Biochem 22 HY Flashcards

1
Q

principle route of metabolism for glucose(and fructose galactose carbs) with or without oxygen

A

glycolysis

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2
Q

where do reactions of glycolysis take place

A

in cytoplasa

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3
Q

in the blood what can you measure to distinguish between respiratory and metabolic acidosis

A

PCO2 and bicarbonate

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4
Q

overall glycolysis rxn

A

Glucose+2Pi+2ADP+2NAD–>2pyruvate+2ATP+2NADH+2H+2H2O

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5
Q

how is glucose transported into cells

A

GLUT transporters stim by insulin or other hormones

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6
Q

In the first reaction of glycolysis D-Glucose–> Glucose-6- P. what enzyme is used in the reaction in all tissues? additional one in the liver? What donates the phosphate? what regulates the enzyme

A

hexokinase; glucokinase; uses ATP; hexokinase activity is inhibited by levels of G6P

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7
Q

when glucose enters the cell why does it need to be phosphorylated

A

once it is phosphorylated it is trapped in the cell

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8
Q

the liver contains both hexokinase and glucokinase to allow glucose entry. what is the significance of glucokinase

A

not inhibited by inc G6P-so that glucose can go to the liver to be stored as glycogen

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9
Q

Glucose-6-P gets converted to fructose6P. After this fructose is converted into what product? what is the enzyme used?

A

Fructose 1,6 bisP; phosphofructokinase-1 uses ATP!

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10
Q

-kinase enzymes in general function

A

use terminal phosphate of P and transfers it to another molecule

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11
Q

phosphofructokinase-2 is an isoenzyme of PFK-1 and is used to transform fructose-6P into

A

fructose, 2,6 bisP

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12
Q

2 things phosphofructokinase-1 enzyme activity increased by and 2 things activity is decreased by

A

high AMP, high fructose2,6,bisP(not a glycolytic intermediate!!!) inc PFK1; high ATP, citrate–>dec PFK1

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13
Q

in the heart unde rischemic conditions AMP levels rise activating protein kinase B which phsophorylates PFK-2 this results in what

A

inc levels of fructose 2,6bisP–>inc PFK-1 activity along with inc AMP–>stimulate glycolysis!!

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14
Q

fructose 1,6 bis P is cleaved by aldolase to form?

A

glyceraldehyde 3P and dihydroxyacetone phosphate

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15
Q

dihydroxyacetone phosphate is isomrized to form

A

glyceraldehyde 3P

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16
Q

the now 2 molecules of glyceraldehyde3P forms 1,3 bisphosphoglycerate in the presence of a low yield enzyme. this step is the only___ step in glycolysis. what is released during this step and what is added to glyceraldehyde3P

A

oxidation step! takes removes high energy electrons puts them on NAD–>NADH!!! phosphate is added to the Glyc3p molecule

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17
Q

1,3bisphosphoglycerate has a high energy P and forms 3 phsophoglycerate. what is generated in this reaction and what type of reaction is this an example of

A

ATP! substrate level phosphorylation(substrate is used to phosphorylate ATP)

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18
Q

3-phosphoglycerate–>2-phosphoglycerate–>Phosphoenolpyruvate what is special about PEP?

A

has another HIGH energy phosphate used to generate ATP via substrate level phosphorylation

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19
Q

Phosphoenolpyruvate in the presence of what enzyme generates pyruvate? what is released

A

pyruvate kinase and ATP is released in this rxn

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20
Q

2 substrates used in substrate level phosphorylation to generate ATP

A

phosphoenolpyruvate and 1,3,bisphosphoglycerate

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21
Q

enzyme pyruvate kinase that is used in rxn PEP–>Pyruvate is inhibitied by what? stimulated by what?

A

ATP; fructose 1,6, bisP

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22
Q

net delta G of glycolysis rxn?

A

negative

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23
Q

2 things the brain depends on for its energy supply

A

glucose and oxygen delivery

24
Q

2 fates of NADH generated by glycolysis

A

enters electron transport chain(aerobic) reoxidized by lactate dehydrogenase to be reused in glycolysis(incytosol is anaerobic)

25
Q

2 fates of pyruvate generated by glycolysis

A

oxidized to acetyl CoA enters TCA cycle or reduced to lactate and diverted away

26
Q

NADH once generated by glycolysis can’t cross the mitochondrial membrane its electrons are donated to DHAP and in the presence of 3P dehydrogenase what is generated? what happens next?

A

glycerol 3P electrons transferred to FADH2 used by CoQ in electron transport chain to generate ATP

27
Q

another alternate NADH pathway is the malate aspartate shuttle. here oxaloacetate accepts electrons from NADH to become malate which passes through the inner mitochondrial membrane and donates its electrons to NAD–>NADH which then enters what to generate ATP

A

electron transport chain

28
Q

starting with glyceraldehyde3P and synthesizing one molecule of pyruvate what is the net ield of ATP and NADH

A

2ATP and 1NADH

29
Q

when glycogen is degraded glucose-1P is isomerized to G6P starting with glucose1P and ending with 2 molecules of pyruvate what is the net yeild of glycolysis in terms of ATP and NADH

A

2 ATP 2 NADH

30
Q

in the beginning of the glycolysis pathway how many ATP are consumed

A

2 molecules

31
Q

what is the result of the glycerol 3 phosphate shuttle? result of the malate aspartate shuttle?

A

NAD+ remains in cytosol for both shuttles and FADH2(G3P) and NADH(Mal/ASP) end up in matrix

32
Q

in anaerobic glycolysis such as what occurs in red blood cells how is NADH recycled to NAD+?

A

by reducing pyruvate to lactate

33
Q

in the presence of oxygen(mitochondria) pyruvate will enter the mitochondria and go to the TCA cycle to yield approx how much ATP

A

12.5 ATP

34
Q

how does lactic acidosis result from anaerobic glycolysis

A

pyruvate is reduced to lactic acid which dissoc into lactate and H+ and enters blood lowering pH

35
Q

lactobacilli and S. Mutans are bacteria found in teeth that use glucose for energy what do they cause/generate

A

lactic acid can cause dental caries

36
Q

in response to hypoxemia what factor is generated in tissues that inc glycolysis transcription factors, causes erythropoiten release, and cause synthesis of NO(vasodilator)

A

HIF-1; hypoxia inducible factor-1

37
Q

in the TCA cycle pyruvate gets completely oxidized to form what

A

CO2

38
Q

tissues with low ATP demand, high levels of glycolytic enzymes and few capilarries such that oxygen has to diffuse over a large distance to reach target cells generate energy via

A

anaerobic glycolysis

39
Q

lactate generated from pyruvate will enter the liver and do what

A

be oxidized back to pyruvate and used to synthesize glucose

40
Q

heart muscle, resting skeletal mm during exercise, and neurons are capable of using what for energy

A

lactate

41
Q

muscle fibers: type I fast are called ___? type IIb slow fibers are called___. which one has a higher content of mitochondria and myoglobin

A

glycolytic fibers; oxidative fibers; oxidative fibers

42
Q

pyruvate dehydrogenase is used to convert pyruvate to acetyl CoA what stimulates its activity? inhibits it?

A

stim by ADP Ca2+ inhibitied by NADH and acetylCoA

43
Q

duringMI absence of oxygen to an ischemic area of the heart woud dec ATP inc AMP and activate PFK-1 so that anaerobic glycolysis and lactate production would occur. what would happen to inhibit this glycolysis so it wouldn’t be able to compensate for the lack of oxidative phosphorylation?

A

increased levels of lactic acid would decrease the pH in the area bc the lactatic acid isn’t getting removed this would inhibit glycolysis

44
Q

lactic acidosis generally results from an increased ration of NADH/NAD+ which ones concentration is increased and what does this cause

A

NADH prevents pyruvate from going to TCA cycle and directs it to form lactate

45
Q

pt has dec PO2 and elevated arterial pCO2 which reulted in an inc in H2CO3 and acidity of the blood. the decreased O2 delivery to tissues resulted in?

A

anaerobic glycolysis–>lactic acidosis; she now has respiratory acidosis and metabolic acidosis

46
Q

how many moles of ATP are generated by the complete aerobic oxidation of 1mol of glucose to 6mol of Co2

A

30-32

47
Q

what is the major purpose of glycolysis

A

to generate energy

48
Q

central role of glycolysis in fuel metabolism

A

ability to generate ATP with and without O2

49
Q

transfer of phosphate from high-energy intermediates of the pathway to ADP

A

substrate level phosphorylation

50
Q

percentage of volume of blood occupied by packed RBCs

A

hematocrit

51
Q

grams of hemoglobin in 100 mL of blood

A

hemaglobin content

52
Q

2 things measured to determine whether the oxygen-carrying capacity of blood is adequate

A

hematocrit and hemaglobin content

53
Q

in anaerobic glycolysis, conversion of glucoose to lactate generates ______ molecules from __________

A

2 ATP; substrate level phosphorylation

54
Q

hormone that maintains blood glucose (homeostatis) ensuring that glucose is always available to cells that depend on glycolysis for generation of ATP

A

insulin and other hormones

55
Q

during fasting, brain continues to oxidize glucose because because

A

has limited capacity for oxidation of fatty acids or other fuels

56
Q

glycolysis is an anabolic pathway that provides

A

biosynthetic precursors

PBL (19 decks)

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