Biochem 22 HY Flashcards by Francine foo

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

glycolysis

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where do reactions of glycolysis take place

in cytoplasa

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

PCO2 and bicarbonate

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overall glycolysis rxn

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

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how is glucose transported into cells

GLUT transporters stim by insulin or other hormones

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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

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

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

once it is phosphorylated it is trapped in the cell

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

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

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

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

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-kinase enzymes in general function

use terminal phosphate of P and transfers it to another molecule

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

fructose, 2,6 bisP

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

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

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

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

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

glyceraldehyde 3P and dihydroxyacetone phosphate

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dihydroxyacetone phosphate is isomrized to form

glyceraldehyde 3P

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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

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

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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

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

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

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

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

pyruvate kinase and ATP is released in this rxn

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2 substrates used in substrate level phosphorylation to generate ATP

phosphoenolpyruvate and 1,3,bisphosphoglycerate

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

ATP; fructose 1,6, bisP

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net delta G of glycolysis rxn?

negative

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2 things the brain depends on for its energy supply

glucose and oxygen delivery

2 fates of NADH generated by glycolysis

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

2 fates of pyruvate generated by glycolysis

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

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?

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

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

electron transport chain

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

2ATP and 1NADH

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

2 ATP 2 NADH

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

2 molecules

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

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

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

by reducing pyruvate to lactate

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

12.5 ATP

how does lactic acidosis result from anaerobic glycolysis

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

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

lactic acid can cause dental caries

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

HIF-1; hypoxia inducible factor-1

in the TCA cycle pyruvate gets completely oxidized to form what

CO2

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

anaerobic glycolysis

lactate generated from pyruvate will enter the liver and do what

be oxidized back to pyruvate and used to synthesize glucose

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

lactate

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

glycolytic fibers; oxidative fibers; oxidative fibers

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

stim by ADP Ca2+ inhibitied by NADH and acetylCoA

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?

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

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

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

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?

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

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

30-32

what is the major purpose of glycolysis

to generate energy

central role of glycolysis in fuel metabolism

ability to generate ATP with and without O2

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

substrate level phosphorylation

percentage of volume of blood occupied by packed RBCs

hematocrit

grams of hemoglobin in 100 mL of blood

hemaglobin content

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

hematocrit and hemaglobin content

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

2 ATP; substrate level phosphorylation

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

insulin and other hormones

during fasting, brain continues to oxidize glucose because because

has limited capacity for oxidation of fatty acids or other fuels

glycolysis is an anabolic pathway that provides

biosynthetic precursors