53: Glycolysis and Hemolysis

Question 1

How does the glucose in blood enter cells?

Answer 1

GLUT transporters by facilitated diffusion

Question 2

Glut 2

Answer 2

liver

Question 3

Glut 1 & 3

Answer 3

neurons and brain

Question 4

Glut 1

Answer 4

erythrocytes

Question 5

Glut 4

Answer 5

adipose tissue and muscle

responsive to insulin

numbers elevated when blood glucose level high

Question 6

Glucokinase

Answer 6

phosphorylates glucose to G6P

in liver has high Km for glucose

present in β cells of pancreas

Question 7

Hexokinase

Answer 7

phosphorylates glucose to G6P

other tissues/RBC, has low Km for glucose

Question 8

Glycolysis

Answer 8

brain and erythrocytes

generate ATP w/ or w/o oxygen

w/ or w/o mitochondria

glycolytic enzymes in cytosol

Question 9

Stage 1: Energy Investment

Answer 9

two irreversible phosphorylation reactions requiring 2 ATP

PFK-1: 2nd reaction, most important regulated step (allosteric regulated)

Question 10

Stage 2: 6C to 3C intermediates

Answer 10

Aldolase cleaves F1,6BP into G3P and DHAP

Aldolase A - muscle
Aldolase B - liver

Triosephosphate isomerase DHAP into G3P

Question 11

Stage 3: Energy Generation

Answer 11

G3PD forms NADH+

1,3 BPG (high energy compound) forms ATP without ETC by Phosphyglycerate kinase

Phosphoenolpyruvate (high energy compound) forms ATP without ETC by pyruvate kinase (irreversible)

Question 12

Pyruvate fate

Answer 12

Aerobic: Pyruvate to Acetyl CoA to TCA cycle

Anaerobic: Lactate to liver via Cori cycle

Question 13

Pyruvate: High NADH levels

Answer 13

reaction toward lactate formation

Question 14

Intense exercise

Answer 14

high NADH/NAD ratio

pyruvate converted to lactate

high lactate in muscle, drop in pH –> cramps

lactate in muscle and RBC diffuse to liver for gluconeogenesis

Question 15

Cardiac muscle

Answer 15

low NADH/NAD ratio

lactate -> pyruvate -> acetyl CoA -> TCA cycle

hypoxia: lactate formation (MI)

Question 16

Arsenate

Answer 16

inhibits glyceraldehyde 3-phosphate dehydrogenase

G3P –> 1,3BPG

Question 17

Fluoride

Answer 17

inhibits enolase

2 phosphoglyerate –> phosphoenolpyruvate

Question 18

2,3 BPG

Answer 18

anaerobic glycolysis

binds to β-globin chains and helps unload oxygen to tissues

formation increased at high altitudes

Question 19

Pyruvate kinase deficiency

Answer 19

decreased ATP generation

ATP maintains electrolyte conc. (Na+/K+ ATPase)

2nd most common form of hemolytic anemia

Question 20

Defect in glycolytic pathway

Answer 20

Pyruvate Kinase or Hexokinase deficiency

RBC lysis

Question 21

Lactic acidosis

Answer 21

metabolic acidosis

pH low, HCO3- decreased, PCO2 decreased

increased pyruvate to lactate (high NADH/NAD ratio)

anaerobic metabolism in tissues b/c of cardiac failure

Lactate not transported to liver

Question 22

Pyruvate Dehydrogenase Deficiency

Answer 22

inherited Leigh disease

Question 23

PFK-1

Answer 23

allosterically regulated enzyme

Fructose-6-Phosphate to Fructose-1,6-Bisphosphate

Question 24

Inhibits glycolysis

Answer 24

ATP (muscle)

Question 25

Stimulates glycolysis

Answer 25

AMP (muscle)

Question 26

Hexokinase deficiency

Answer 26

Hemolytic anemia