Glycolysis

Question 1

family of glucose carrier proteins that transport glucose into the cell

Answer 1

GLUT

Question 2

glucose transporter used by liver & pancreas

Answer 2

GLUT2

Question 3

glucose transporter used by muscle & adipose

Answer 3

GLUT4

Question 4

Which GLUT is sensitive to insulin

Answer 4

GLUT4

Question 5

glucose transport is coupled with

Answer 5

Sodium

Question 6

Glucose is trapped in the cell by phosphorylation by what enzyme

Answer 6

Hexokinase
Glucose 6P can’t be transported across plasma membrane
it enters various metabolic pathways

Question 7

What inhibits hexokinase

Answer 7

feedback inhibition by its product glucose 6-P

Question 8

in liver, glucose is phosphorylated by what enzyme

Answer 8

glucokinase

Question 9

major distinction between hexokinase and glucokinase

Answer 9

glucokinase requires a much larger glucose concentration to achieve half saturation
higher Km

Question 10

Does glucokinase or hexokinase prevent hyperglycemia following a carbohydrate-rich meal?

Answer 10

glucokinase functions to prevent hyperglycemia following a carbohydrate rich meal

Question 11

Which 2 organs express glucokinase ?

Answer 11

liver and pancreas

Question 12

Describe the kinetics of glucokinase

Answer 12

liver
high Km (low affinity for glucose)
high Vmax
not subject to feedback inhibition by glucose 6-P

Question 13

Describe the kinetics of hexokinase

Answer 13

brain , muscles
low Km (high affinity for glucose)
low Vmax
subject to feedback inhibition by glucose 6-P

Question 14

What is the effect of insulin on this glucokinase?

Answer 14

insulin induces synthesis of the glucokinase

Question 15

Name 2 functions of glycolysis

Answer 15

degrading glucose to generate ATP

providing building blocks for synthetic reactions

Question 16

how much ATP is consumed per mole of glucose that undergoes glycolysis

Answer 16

2 moles are consumed

Question 17

how much ATP is generated per mole of glucose that undergoes glycolysis

Answer 17

4 moles generated

Question 18

What is the net generation of ATP per mole of glucose - glycolysis

Answer 18

2 moles

Question 19

What is the Major Regulatory enzyme in Glycolysis

Answer 19

Phosphofructokinase-1 (PFK1)

Question 20

Name 3 enzymes of glycolysis that catalyze virtually Irreversible reactions

Answer 20

Hexokinase
PFK-1
pyruvate kinase (in liver)

Question 21

What reaction does PFK-1 catalyze?

Answer 21

fructose 6-P –> fructose 1,6-bisphosphate

coupled to hydrolysis of ATP

Question 22

Positive allosteric regulator of PFK1

Answer 22

AMP (+)

fructose-2,6-bisphosphate (+)

Question 23

Allosteric inhibitor of PFK1

Answer 23

ATP (-)

citrate (-)

Question 24

What reaction does PFK II catalyze?

Answer 24

fructose 6-P –> fructose 2,6-bisphosphate

Question 25

PRK II is a sign of fed or fasting state?

Answer 25

fed

Question 26

which 2 glycolytic intermediates liberate enough energy for driving ATP synthesis?

Answer 26

1,3-bisphosphoglycerate and phosphoenolpyruvate (PEP)

Question 27

What are the 2 ATP-producing enzymes of glycolysis?

Answer 27

3-phosphoglycerate kinase and pyruvate kinase

Question 28

Pyruvate kinase catalyzes what reaction?

Answer 28

PEP --> pyruvate

Question 29

What covalent modification inhibits pyruvate kinase?

Answer 29

Phosphorylation

Question 30

What enzyme phosphorylate pyruvate kinase?

Answer 30

Protein Kinase A

Question 31

Name the allosteric inhibitors of Pyruvate Kinase

Answer 31

ATP acetyl coenzyme (CoA) alanine in liver only

Question 32

Name the allosteric activator of pyruvate kinase

Answer 32

fructose-1,6-bisphophate

Question 33

Which enzyme produces Nicotinamide Adenine Dinucleotide in Glycolysis?

Answer 33

glyceraldehyde-3-phosphate dehydrogenase

Question 34

How much NADH is produced per mole of glucose oxidized to pyruvate

Answer 34

2 moles

Question 35

Since erythrocytes do not contain mitochondria, what is the NADH produced in glycolysis used for?

Answer 35

to reduce pyruvate to lactate

Question 36

How is the reducing power of NADH transferred to the mitochondria?

Answer 36

via the glycerol-3-phopshate shuttle or malate aspartate shuttle

Question 37

What are the possible fates of pyruvate produced in the cell?

Answer 37

``` it can be converted to lactate- LDH alanine acetyl CoA- PDC OAA- Pyruvate Carboxylase ```

Question 38

How many moles of ATP are required to generate glucose from pyruvate?

Answer 38

6 moles

Question 39

Under anaerobic conditions, pyruvate is converted to what molecule?

Answer 39

Lactate

Question 40

What enzyme catalyzes pyruvate to lactate?

Answer 40

Lactate dehydrogenase

Question 41

What reaction does the PDH complex catalyze?

Answer 41

Pyruvate + NAD+ + CoA --> Acetyl-CoA + CO2 + NADH

Question 42

What coenzymes are required by this enzyme?

Answer 42

``` Thiamine pyrophosphate coenzyme A NAD+ flavin adenine dinucleotide lipoid acid ```

Question 43

PDH complex is similar to what other enzyme

Answer 43

alpha-ketoglutarate dehydrogenase complex

Question 44

PDH complex active in phosphorylated or nonphosphorylated state?

Answer 44

nonphosphorylated state

Question 45

what enzyme phosphorylates the PDH complex?

Answer 45

PDH kinase

Question 46

What molecules activate PDH kinase (thus inhibiting the PDH complex)?

Answer 46

Acetyl CoA | NADH

Question 47

What molecules inhibit PDH kinase (thus activating the pyruvate dehydrogenase complex)?

Answer 47

Pyruvate | decreased levels of ADP

Question 48

What enzyme dephosphorylates PDH complex?

Answer 48

PDH phosphorylase / phosphatase

Question 49

What molecule activates PDH phosphatase (thus activate PDH complex)?

Answer 49

Ca2+

Question 50

What are the major manifestations of PDH deficiency?

Answer 50

Lactic acidosis | neurological manifestations

Question 51

What is the treatment for PDH deficiency?

Answer 51

Increased intake of ketogenic nutrients

Question 52

SGLT1

Answer 52

small intestine, kidney | absorption of glucose

Question 53

GLUT2

Answer 53

liver and pancreatic beta cells high Km (low affinity for glucose) only transport glucose at high blood concentration high Vmax

Question 54

GLUT4

Answer 54

skeletal muscle and adipose insulin responsive low Km (high affinity for glucose)

Question 55

glucose 6-P fates

Answer 55

glycogen pyruvate ribose 5-P other pathways

Question 56

BPG shunt

Answer 56

1,3-bisphosphoglycerate - critical metabolic intermediate of glycolysis shunt - glycolytic bypass unique to RBC , decrease in ATP production regulate oxygen binding of hemoglobin produces 2,3-BPG regulated by 2,3BPG mutase/phosphatase

Question 57

2,3-BPG

Answer 57

lowers affinity of Hb for Oxygen | allowing O2 release in peripheral tissue

Question 58

glycolysis - delta G

Answer 58

negative delta G | -22 kcal

Question 59

Anerobic glycolysis produces no net change

Answer 59

NADH | NADH is reoxidized in cytosol by lactate dehydrgoensase

Question 60

conversion of glucose to 2 lactate generates

Answer 60

2 ATP from substrate level phosphorylation

Question 61

Lactic acidemia (acidosis)

Answer 61

blood lactate >5 mM pH high NADH/NAD+ and low ATP Tissue hypoxia

Question 62

Anerobic glycolysis vs Aerobric glycolysis

Answer 62

Anaerobic- 2 ATP , 2 Lactate | Aerobic- 2 ATP, 2 NADH , 2 pyruvate ~25ATP

Question 63

Brain & Muscle Pyruvate Kinase regulation?

Answer 63

contains no Allosteric Sites | no regulation

Question 64

Liver Pyruvate Kinase regulation?

Answer 64

``` has allosteric sites ATP (-) Fructose 1-6-P (+) cAMP-PKA- phosphorylation (-) , fasting - glucagon high alanine (-) ```

Question 65

Phosphofructokinase 1 regulation?

Answer 65

AMP, ADP (+) fructose 2,6-bisP (+)- fed state- high insulin ATP (-) citrate (-)

Question 66

Substrate level phosphorylation

Answer 66

formation of high energy phosphate bond where none previously existed w/o utilization of oxygen