biochem, block 2

Question 1

glycolysis - hexokinase vs glycokinase

Answer 1

hexo - all cells - low vmax, no insulin needed, inhibited by G6P - prevents hoarding of glucose

Question 2

when g6p levels high, what happens? glucose 6 phosphate ?

Answer 2

no trapping of glucose - hexokinase inhibited - prevents hoarding of glucose in cells

Question 3

when frucose6p HIGH, what happens? and glucose levels low? IF glucose levels high - can overcome this, and glucokinase will start storing glucose as glycogen

Answer 3

glucokinase inhibited, will not be trapping glucose = will not be undergoing glycolysis by glucokinase - because liver is working in opposite way - making glucose re need the energy - in fasting state (glucose levels down)

Question 4

where is glucokinase?

Answer 4

liver and pancreas, it locks in glucose by phosphorylating it - but only happens when glucose levels are high - NEEDs INSULIN

Question 5

is hexokinase or glucokinase inhibited by high levels of g6p?

Answer 5

hexokinase - high levels of g6p show that there is plenty of glucose stored in the cell, prevents hoarding

Question 6

glucokinase regulatory protein? GKRP? to nucleus! exc. glucose levels high

works with high levels of fructose 6 P

Answer 6

translocates glucokinase to nucleus (which inhibits activity), exc when glucose levels high - glucose high, bumps glucokinase back in to cytoplasm

Question 7

glucose competes with ? for glucokinase binding?

Answer 7

GKRP - if glucose high, will bind instead of GKRP - and allow glycolysis to move forward

Question 8

Fructose 6 phosphate high - what happens?

Answer 8

allows GKRP binding with glucokinase - takes to nucleus when inactivated UNLESS glucose high - then glucose binds with glucokinase - and keeps in cytoplasm for production

Question 9

When is glucokinase inactive? 2 things:

Answer 9

1. high F6P
2. low glucose

so regardless of high levels of F6P, if glucose high, liver will store glucose as glycogen

Question 10

low blood sugar?

Answer 10

1. hexokinase active
2. glucokinase not active
   glucose stays in tissues, not liver

Question 11

high blood sugar

Answer 11

1. high G6P inactivates hexokinase - stops hoarding
2. glucokinase in liver working, stores glucose

usually after a meal - insulin high, glucose high

Question 12

glukokinase deficiency - exacerbated during pregnancy

Answer 12

born with this - hyperglycemia - liver takes up less glucose after a meal - generally symptoms mild, - when glucose gets high enough - pancreas will release insulin

Question 13

Rate limiting step in glycolysis?

Answer 13

fructose 6 phosphate to fructose 1, 6 BIZ - SLOWEST - with PRK1

Question 14

PFK1? Phosphofructokinase 1?

Answer 14

2nd irrev step, commits glucose to glycolysis, consume 1 ATP, RATE LIMITING

Question 15

inhibiting 2nd irreversible step?

Answer 15

cell energy high - citrate, ATP,

Question 16

activating 2nd irreversible step?

Answer 16

cell energy low, lots of AMP, Fructose 2 6 biz

Question 17

fructose 2, 6, Bizphosphate? turns glycolysis ON , OFF

Answer 17

when high - glycolysis ON, when low - OFF - gluconeogenesis

Question 18

Insulin - wants ? High F2,6 BP

Answer 18

glycolysis - wants dephosphorylation, raises F2,6, BP - turns on glycolysis

Question 19

Fed state - Insulin up or down? F2,6 BP up or down?, glycolosis, up or down

Answer 19

All UP F2,6BP is DEphosphorylated

Question 20

Fasting state -

Answer 20

insulin down, f2,6 BP down, glycolosis DOWN -

F2,6BP turns OFF glycolysis

it is phosphoylated

Question 21

splitting stage?

Answer 21

6 carbon to 2 - 3 carbons GAP - and DAP (which can become GAP)

Question 22

Energy stage? Inhibited by?

Answer 22

ATP, Alanine

Question 23

Energy stage, Activated by? Feed forward?

Answer 23

Fructose 1, 6 BP (from priming stage)

Question 24

When in energy stage is NADH created?

Answer 24

GAP3 to 1 - 3 biz (first step)

Question 25

When are the two ATPS generated in energy stage?

Answer 25

2nd step (1 -3 biz to 3 phospho), ENOLpyruvate - pyruate

Question 26

Alanine cycle?

Answer 26

When M don’t have enough glucose, break down protein, release AA alanine in blood, LIVER sees, Inhibits pyruvate Kinase - stops glycolosis last step - and then LIVER turns Alanine into glucose via gluconeogenesis and sends back to M

Question 27

Glucagon, EPInephrine hormones, how affect glycolysis?

Answer 27

Inactivates pyruvate Kinase - slows glycolysis

Question 28

Alanine transaminase? ALT

Answer 28

enzyme breaking AA protein down in blood - releases alanine

Question 29

Pyruvate? how to get max ATP?

Answer 29

TCA cycle - need oxygen

Question 30

no oxygen? what to do with pyruvate? Regenerates NAD+

Answer 30

converts to Lactage - w/ LDH - lactate dehydrogenase

Question 31

LDH? high levels? in plasma - lots of clinical relevance

Answer 31

heart attacks, hemolysis (LDH spills out when RBC are dying), some tumors - pleural effusion can measure to see if transudate vs. exudate (pulmonary issues)

Question 32

Cells need NAD+ - if plenty of oxygen - no problem - go to mitochondria - make more NAD+ from NADH via oxidative phosphoylation

Answer 32

if O2 not present - pyruvate to lactate regenerates NAD+

creates lactate acid -

Question 33

lactic acidosis occurs when?

SEPSIS, bowel ischemia, seizures

Answer 33

lack of oxygen, cells need NAD+, so change pyruvate to lactate, created lactic acid, Ph down, HCO3 down, elevated anion gap acidosis, SEPSIS, bowel ischemia, seizurees

Question 34

muscle cramps - too much NAD consumption, exceed capacity of TCA cycle -

Answer 34

elevated NADH/NAD ratio

ph falls, cramps

long distance runners, lots and bigger mitochondria

Question 35

Pyruvate Kinase Deficiency

Anemia, Amish higher risk to develop , chrom 1Q21

auto recessive

precipitative factos - oxidant stress, infection

Answer 35

most affected cells RBC - lack mitochondria - require pyruvate kynase for anaerobic metabolism, Loss of ATP, Membrane failure - phagocytose

Usually in newborns

Extravascular hemolysis, Spleneomegaly

Disease severity ranges

Question 36

Pyruvate Kinase Deficiency?

Na/K+ pump using ATP keeps shape of RBCs - lack of ATP, means shape is lost

Answer 36

50% less ATP created, loss of water and K+ in cells / gain Ca+, becomes rigid, susceptible to damage by shear factors during circulation, once damaged are removed, hence anemia

Question 37

What do Heinz bodies indicate??

Answer 37

The presence of Heinz bodies on a blood smear test indicates oxidative damage to the hemoglobin in red blood cells. Conditions associated with Heinz bodies include certain blood conditions, such as thalassemia or hemolytic anemia

Question 38

2,3 bizphosphoglyceride pathway and hemoglobin?

2,3BPG alters Hgb binding

works if live in high altitude - helps deliver oxygen - easier for RBC to offload oxygen

Answer 38

can divert molecules along glycolysis energy stage pathway - and create 2,3 BPG bisphospho using 2,3, BPG Mutase - helps RBCs deliver oxygen to cells, BUT, RBCs have to sacrifice use of the ATP that is NOT being generated via glycolysis

Question 39

2,3 Bizphopho - increases or decreases oxygen affinity of Hb to 02?

Answer 39

Decreases - allows oxygen to be released more easily

shift disossociation curve to right

Question 40

lactic acidosis? failure to deliver oxygen to cells?

pH below 7.2

Answer 40

see in myocardial infarctions, uncontrolled hemorrhage, consumption LOTS of Alcohol

Question 41

Cancer and glycolysis? Warburg effect?

Answer 41

Cancer loves glycolysis over oxydative phosphorylation -

TUMOR Cells convert pyruvate to lactate

Question 42

What is the process of oxidative phosphorylation?

Answer 42

Oxidative phosphorylation is the process in which ATP is formed as a result of the transfer of electrons from NADH or FADH 2 to O 2 by a series of electron carriers. This process, which takes place in mitochondria, is the major source of ATP in aerobic organisms

Question 43

Which metabolite is able to activate pyruvate kinase?

Answer 43

Fructose-1,6-bisphosphate STIM “feed forward:

Inhib - ALANINE, ATP

Question 44

hemolytic anemia - destruction RBC

non-hemolytic - decreased produciton

Answer 44

hemolytic where there’s increased destruction of red blood cells and non-hemolytic where there’s decreased production of red blood cells in the bone marrow.

Question 45

Pyruvate Kinase Deficiency

Answer 45

RBCs lyse, can’t do glycolysis - ANEMIA - Auto recessive, often see echinocytes (hedgehog shaped RBCs)

Question 46

3 major regulators of glycolysis

Answer 46

hesokinase, phosphofructokinase, pyruvate kinase

Question 47

RBCS - no mitochondria - how get energy?

Answer 47

glycolysis - can’t ???

Question 48

Fluoride in dentist?

Answer 48

2-phosphoglycerate accumulates -

oride inhibits the glycolytic enzyme enolase, which catalyzes the dehydration

of 2-phosphoglycerate to phosphoenolpyruvate. Thus, 2-phosphoglycerate accumulates under these conditions.

Question 49

Which one of the following enzymes catalyzes high-energy phosphorylation of substrates during glycolysis?

a. Pyruvate kinase Incorrect
b. Aldolase
c. Triose phosphate isomerase
d. Glyceraldehyde-3-phosphate dehydrogenase
e. Phosphoglycerate kinase

Answer 49

High-energy phosphate bonds are added to the substrates of glycolysis at three steps in the pathway. Hexokinase—or, in the case of liver, glucokinase—adds phosphate from ATP to glucose to form glucose-6-phosphate. Strictly speaking, this is not always considered a step of the glycolytic pathway. Phosphofructokinase uses ATP to convert fructose-6-phosphate to fructose-1,6-phosphate. Using NAD+ in an oxidation-reduction reaction, inorganic phosphate is added to glyceraldehyde-3-phosphate by the enzyme glyceraldehyde-3 phosphate dehydrogenase to form 1,3-diphosphoglycerate. The enzymes phosphoglycerate kinase and pyruvate kinase transfer substrate highenergy phosphate groups to ADP to form ATP.

Question 50

During the first week of a diet of 1500 calories per day, the oxidation of glucose via glycolysis in the liver of a normal 59-kg (130-lb) woman is inhibited by the lowering of which one of the following?

Select one:

a. Citrate
b. Fatty acyl-CoA
c. Fructose-2,6-bisphosphate
d. ATP Incorrect
e. Ketone bodies

Answer 50

c. Fructose-2,6-bisphosphate

The main control of glycolysis is through the enzyme phosphofructokinase. This enzyme is controlled by a high level of ATP, which inhibits it, or a high level of fructose-2,6 bisphosphate (F-2,6-BP), which activates it. The inhibitory effect of ATP is potentiated by citrate, while high AMP levels reverse it. During fasting, when blood glucose levels are low, a glucagon-signaled increase of liver cyclic AMP leads to the activation of a phosphatase that hydrolyzes the 2-phosphoryl group from F-2,6-BP. The same glucagon-stimulated cascade deactivates the kinase that phosphorylates fructose-6-phosphate. The subsequent lowering of F-2,6-BP inactivates phosphofructokinase.

Question 51

Which one of the following enzymes catalyzes phosphorylation with the use of inorganic phosphate?

Select one:

a. Pyruvate kinase
b. Phosphofructokinase Incorrect
c. Hexokinase
d. Glyceraldehyde-3-phosphate dehydrogenase
e. Phosphoglycerate kinase

Answer 51

Glyceraldehyde-3-phosphate dehydrogenase

All the enzymes named are glycolytic enzymes that carry out phosphorylation of glucose-derived substrates or of ADP to form ATP. However, only the reaction catalyzed by glyceraldehyde-3-phosphate dehydrogenase is a phosphorylation reaction coupled to oxidation that uses inorganic phosphate. In this reaction,

glyceraldehyde-3-phosphate is converted to 1,3 bisphosphoglycerate by the addition of inorganic phosphate and the oxidation of glyceraldehyde- 3-phosphate with the concomitant reduction of NAD+ to NADH + H+. This reaction is an example of a high-energy phosphate compound being produced by an oxidation-reduction reaction. The oxidation of the aldehyde group at C1 of glyceraldehyde-3-phosphate provides the energy for the reaction. The 1,3-bisphosphoglycerate can then be utilized to phosphorylate ADP to ATP through the action of phosphoglycerate kinase, which is the next step in the glycolytic pathway.

Question 52

Which of the following is an allosteric effector that enhances activity of phosphofructokinase of the glycolytic pathway?

ADP - ATP would inhibit

Select one:

a. Adenosine triphosphate (ATP) Incorrect
b. Adenosine monophosphate (AMP)
c. Glucose
d. Glucose-6-phosphate
e. Citric acid

Answer 52

The glycolytic pathway has three key irreversible enzymes: hexokinase, phosphofructose kinase, and pyruvate kinase. Under conditions of limiting cellular energy (low-energy charge), ADP and AMP accumulate and positively regulate phosphofructokinase. Under conditions of cellular “plenty,” ATP and citrate, both negative effectors of phosphofructokinase, accumulate. When phosphofructokinase is inhibited, glucose-6-phosphate accumulates and shuts off hexokinase ATP, inhibiting the regulatory enzymes of glycolysis, while a lower energy charge actually stimulates glycolysis.

Question 53

A scientist is studying oxidative phosphorylation in intact, carefully isolated mitochondria. Upon adding an oxidizable substrate, such as pyruvate, a constant rate of oxygen utilization is noted. The scientist then adds a compound that greatly enhances the rate of oxygen consumption. This compound is most likely which one of the following?

Select one:

a. Cyanide
b. Carbon monoxide Incorrect
c. Dinitrophenol
d. Rotenone
e. Antimycin

Answer 53

An uncoupler was added to the mitochondria to greatly increase the rate of oxygen consumption. Dinitrophenol will allow free proton diffusion across the inner mitochondrial membrane, thereby dissipating the proton gradient and preventing ATP synthesis. With- out an existing proton gradient to ‘‘push’’ against, electron flow through the electron transport chain is accelerated, resulting in enhanced oxygen consumption. Rotenone inhibits electron transfer from complex I to coenzyme Q. Carbon monoxide and cyanide block complex IV from accepting electrons. Antimycin blocks electron flow from complex III.

Since electron flow is blocked using rotenone, carbon monoxide, cyanide, or antimycin, oxygen uptake will cease.

The correct answer is: Dinitrophenol

Question 54

A 53-year-old, previously successful man recently lost his job and is under investigation for racketeering. His wife returns home to find him slumped over the steering wheel of his idling car in the closed garage. He is unresponsive and has a cherry color to his lips and cheeks. Which of the following is inhibited by the carbon monoxide in the car’s exhaust fumes?

Select one:

a. The F0 component of the F0-F1 ATPase
b. Cytochrome oxidase Correct
c. The F1 component of the F0-F1 ATPase
d. Complex I of the ETC
e. The ATP-ADP antiporter

Answer 54

In addition to binding the iron in hemoglobin and impairing oxygen transport, carbon monoxide also terminates cellular respiration by inhibiting cytochrome oxidase, which contains a heme iron. Amytal, a barbiturate, inhibits complex I of the ETC. There are no iron- containing cytochromes in complex I because complex I contains proteins with iron-sulfur cen- ters. The ATP-ADP antiporter is inhibited by the plant toxin atractyloside. The F0 component of the F0-F1 ATPase is inhibited by the drug oligomycin. There is no inhibitor for the F1 component of the proton-translocating ATPase.

The correct answer is: Cytochrome oxidase

Question 55

A comatose laboratory technician is rushed into the emergency room. She dies while you are examining her. Her most dramatic symptomis that her body is literally hot to your touch, indicating an extremely high fever. You learn that her lab has been working on metabolic inhibitors andthat there is a high likelihood that she accidentally ingested one. Which one of the following is the most likely culprit?

brown fat same theory

Select one:

a. Dinitrophenol Correct
b. Dimercaprol
c. Cyanide
d. Piericidin A
e. Barbiturates

Answer 55

All of the poisons shown affect either electron transport or oxidative phosphorylation. Dinitrophenol is unique in that it disconnects the ordinarily tight coupling of electron transport and phosphorylation. In its presence, electron transport continues normally with no oxidative phosphorylation occurring. Instead, heat energy is gen- erated. The same principle is utilized in a well-controlled way by brown fat to generate heat in newborn humans and cold-adapted mammals. The bio- logical uncoupler in brown fat is a protein called thermogenin. Barbitu- rates, the antibiotic piericidin A, the fish poison rotenone, dimercaprol, and cyanide all act by inhibiting the electron transport chain at some point.

Question 56

Which of the following statements about flavoproteins is true?

Select one:

a. They do not participate in oxidation of NADH dehydrogenases
b. They cannot produce hydrogen peroxide
c. They can be associated with sulfur and nonheme iron Correct
d. They are not oxidized by coenzyme Q
e. They receive electrons from cytochrome P450 in liver mitochondria

Answer 56

Some monooxygenases found in liver endoplasmic reticulum require cytochrome P450. This cytochrome acts to transfer electrons between NADPH, O2, and the substrate. It can be an elec- tron acceptor from a flavoprotein. In the mitochondrial electron transport chain, flavoproteins donate electrons to coenzyme Q, which then transfers them to other cytochromes. Flavoproteins that are oxidases often react directly with molecular oxygen to form hydrogen peroxide. Flavoproteins can be NADH dehydrogenases that oxidize NADH and transfer the elec- trons to coenzyme Q. The electron transfer centers of flavoproteins in the electron transport chain contain nonheme iron and sulfur.

Question 57

Inhibition of the synthesis of ATP during oxidative phosphorylation by oligomycin is thought to be due to

Select one:

a. Uncoupling of electron transfer between NADH and flavoprotein
b. Dissociating of cytochrome c from mitochondrial membranes
c. Inhibiting of mitochondrial ATPase (ATP synthase) Correct
d. Blocking of the proton gradient between cytochrome c1 and cytochrome c
e. Blocking of the proton gradient between NADH-Q reductase and QH2

Answer 57

Oligomycin inhibits mitochondrial ATPase and thus prevents phosphorylation of ADP to ATP. It prevents uti- lization of energy derived from electron transport for the synthesis of ATP. Oligomycin has no effect on coupling but blocks mitochondrial phosphor- ylation so that both oxidation and phosphorylation cease in its presence.

The correct answer is: Inhibiting of mitochondrial ATPase (ATP synthase)

Question 58

The pyruvate dehydrogenase complex (PDHc) is a multi-subunit enzyme whose activity is regulated by both allosteric effectors and covalent modification. Which of the following exerts a positive influence on the activity of PDHc toward pyruvate?

Select one:

a. acetyl-CoA
b. NADH
c. ATP
d. phosphorylation Incorrect
e. dephosphorylation

Answer 58

The level of active PDHc is controlled by its state of phosphorylation. A family of enzymes called the PDH kinases phosphorylates the PDHc. In order to return the PDHc to full activity following PDH kinase-mediated phosphorylation, the phosphates are removed by PDH phosphatase.

The correct answer is: dephosphorylation

Question 59

In the TCA cycle, GTP is produced via a process referred to as substrate-level phosphorylation. Which of the following enzymes is involved in this process of formation of GTP from GDP?

Select one:

a. succinate dehydrogenase Incorrect
b. citrate synthase
c. succinate-CoA synthetase
d. malate dehydrogenase
e. isocitrate dehydrogenase

Answer 59

Succinyl-CoA synthetase catalyzes the conversion of succinyl-CoA to succinate. Simultaneously, the reaction generates GTP from GDP, utilizing the

high-energy bond between CoA and succinate. This formation of GTP is referred to as substrate-level phosphorylation to distinguish it from ATP production during oxidative phosphorylation.

The correct answer is: succinate-CoA synthetase

Question 60

Pantothenate is vitamin B5.

Answer 60

Vitamins are naturally occurring substances necessary for many processes in the body. Pantothenate is important for the breakdown of the foods we eat into substances the body can use. Pantothenate is also important in the creation of hormones and other substances in the body.

Question 61

vitamin B2

Answer 61

riboflavin

Question 62

Transfer of H+/e− pairs to electron transport carriers, decarboxylation, and substrate-level phosphorylation occur at some of the steps shown in the following diagram of the citric acid cycle. All three of these events occur at which step?

Answer 62

α-ketoglutarate to succinate

In the citric acid cycle, the conversion of α-ketoglutarate to succinate results in decarboxylation, transfer of an H+/e− pairtoNADH+H+,andthesubstrate-levelphosphorylationofGDPtoGTP. The series of reactions involved is quite complex. First, α-ketoglutarate reacts with NAD+ + CoA to yield succinyl CoA + CO2 + NADH + H+. These reactions occur by the catalysis of the α-ketoglutarate dehydrogenase com- plex, which contains lipoamide, FAD+, and thiamine pyrophosphate as prosthetic groups. Under the action of succinyl CoA synthetase, succinyl CoA catalyzes the phosphorylation of GDP with inorganic phosphate cou- pled to the cleavage of the thioester bond of succinyl CoA. Thus, the pro- duction of succinate from α-ketoglutarate yields one substrate-level phosphorylation and the production of three ATP equivalents from NADH via oxidative phosphorylation.

Question 63

A family that had previously had a newborn boy die of a metabolic disease has just given birth to another boy, small for gestational age, and with low Apgar scores. The child displayed spasms a few hours after birth. Blood analysis indicated extremely high levels of lactic acid. Analysis of cerebrospinal fluid showed elevated lactate and pyruvate. Hyperalaninemia was also observed. The child died within 5 days of birth. The biochemical defect in this child is most likely which of the following?

Select one:

a. Citrate synthase
b. The E2 subunit of pyruvate dehydrogenase Incorrect
c. Malate dehydrogenase
d. The E3 subunit of pyruvate dehydrogenase
e. The E1 subunit of pyruvate dehydrogenase

Answer 63

The E1 subunit of pyruvate dehydrogenase

Lactic acidosis can result from a defect in an enzyme that metabolizes pyruvate (primarily pyruvate dehydrogenase and pyruvate carboxylase). The pyru- vate dehydrogenase complex consists of three major catalytic subunits, designated E1, E2, and E3. The E1 subunit is the one that binds thiamine pyrophos- phate and catalyzes the decarboxylation of pyruvate. The gene for the E1 subunit is on the X chromosome, so defects in this subunit are inherited as X-linked diseases, which primarily affects males. Since this is the second male child to have these symptoms, it is likely that the mother is a carrier for this disease. The pattern of inheritance distinguishes this diagnosis from that of an E2 or E3 deficiency. In addition, an E3 deficiency would affect more than pyruvate metab- olism, as this subunit is shared with other enzymes that catalyze oxidative decarboxylation reactions, and other metabolites would also be accumulating. Defects in citrate synthase and malate dehydrogenase would not lead to severe lactic acidosis and would not be male-specific disorders. As an example, the three subunits of α-ketoglutarate dehydrogenase are shown below.

Question 64

A 5-year-old child was rushed to emergency room after accidentally consuming fluoroacetate, a known inhibitor of TCA cycle. Which of the following enzymes is inhibited by fluoroacetate?

Answer 64

aconitase (isocitrate to alpha keto) Fluoroacetate is a structural analog of citrate and a strong competitive inhibitor of aconitase.

Question 65

PDH complex

Answer 65

3 enzymes, 5 cofactors

Pyruvate dehydrogenase complex

Mitochondrial enzyme complex linking glycolysis and TCA cycle. Differentially regulated in fed (active)/fasting (inactive) states.

Reaction: pyruvate + NAD++ CoA acetyl-CoA + CO2+ NADH.

Contains 3 enzymes requiring 5cofactors:

1. Thiamine pyrophosphate (B1)
2. Lipoic acid (arsenic)
3. CoA (B5, pantothenic acid)
4. FAD (B2, riboflavin)
5. NAD+(B3, niacin)

Activated by: NAD+/NADH ratio, ADP Ca2+.

The complex is similar to the α-ketoglutarate dehydrogenase complex (same cofactors, similar substrate and action), which converts α-ketoglutarate succinyl-CoA (TCA cycle).

The Lovely Coenzymes For Nerds.

Arsenic inhibits lipoic acid. Arsenic poisoning clinical findings: imagine a vampire (pigmentary skin changes, skin cancer), vomiting and having diarrhea, running away from a cutie (QT prolongation) with garlic breath

Question 66

anerobic lactate formation in muscle is due to?

forming NAD+ for GA3P glycolysis to proceed

Answer 66

providing substrate for glyceraldehyde 3 phosphate dehydrogenase -

normally NADH generated at this stage goes to ETC, but no oxy, so NADH is accumulating in cell, NAD+ decreases which would inhibit glycolysis - to avoid this, lactate dehydrogenase converts pyruvate to lactate, generating NAD+ as a substrate for GA3P

Question 67

in muscle under anerobic condition - one glucose mole produces how much ATP?

Answer 67

3 -

Question 68

raw eggs?

Answer 68

reduces glucose production - reduces effectivenexx of carboxylation reaction = a necessary step in gluconeogenic pathway - liver can’t maintain blood glucose levels

Question 69

why is alcoholic hypoglycemic?

Answer 69

high NADH/NAD+ ratio impairs gluconeogenesis

liver glycogen stores depleted within 36 hours -

ethoanol oscydation leads to large amounts of NADH

Question 70

fruit juice problems?

Answer 70

aldolase - genetic - fructose intolerance

Question 71

3 major precursors of gluconeogenesis?

Answer 71

glycerol, lactate, AAs (glutamine - maybe others - not leucine - gives rise only to acetyle=CoA - cant be used for glucose production) - it’s ketogenic

Question 72

28 yo develops diabetes - may be a mutation in ?

Answer 72

pancreatic glucokinase - MODY

Question 73

catarracts at young age (e months)

Answer 73

defect in galactokynase - galactose can’t be accumulated, spills into urine and into eye - aldose reductase traps in eye