TBL 3 - Glycolysis, pentose phosphate pathway and regulation

Question 1

The chemical equation for glycolysis

Answer 1

Glucose + 2NAD+ + 2 ADP + 2Pi –> 2 Pyruvate + 2 NADH + 2 H+ + 2 ATP

Question 2

Glycolysis regualtion occurs at which 3 points? They are (irreversible or reversible)?

Answer 2

Hexokinase, phosphofructokinase, and pyruvate kinase

Irreversible

Question 3

Net yield ATP in glycolysis

Answer 3

2 ATP

Question 4

Anaerobic respiration process:

Net yield ATP:

Answer 4

Lactate dehydrogenase oxidizes NADH (which comes from glycolysis) by reducing pyruvate to lactate

2 ATP

Question 5

Hexokinase vs glucokinase

Answer 5

Isozymes

Hexokinase: present in all tissues, is active at low concentrations of glucose, low Km, low Vmax

Glucokinase: present in liver and pancreatic-β-cells, is a active at high concentrations of glucose, high Km, high Vmax

Question 6

Glycerol-3-phosphate (GAP) in the fed state:

Answer 6

Used as a substrate for triacylglycerol synthesis in the liver during the fed state

Question 7

Glycerol-3-phosphate (GAP) in the fasting state:

Answer 7

GAP is converted to DHAP which is used as a substrate for gluconeogenesis

Question 8

Pyruvate Kinase deficiency

Answer 8

Autosomal recessive disorder
#1 cause of hemolytic anemia
Red blood cells break down too easily
Cause yellowing of eyes, fatigue, recurrent gall stones, jaundice, and pallor

Question 9

Pyruvate Kinase deficiency pathology

Answer 9

decreased ATP > decreased Na+/K+ ATPase . loss of ioin balance > increase in osmotic fragility > swelling and lysis

Question 10

Pentose phosphate pathway (PPP) or Hexose monophosphate shunt (HMP)

Answer 10

Process by which cels can generate NADPH

Occurs in Cytosol

Question 11

PPP/HMP occurs in what organs/regions in the body?

Answer 11

Liver, adipose, adrenal, RBCs and mammary glands

Question 12

The oxidative phase in the PPP

Answer 12

3 irreversible reactions which turn glucose-6-phosphate to ribose-5-phosphate with release of CO2 and 2 NADPH molecules

Question 13

Glucose-6-phosphate dehydrogenase deficiency

Answer 13

Causes hemolytic anemia
X-linked recessive disease
Is most apparent when demand for NADPH increases (infection, fava bean consumption, and oxidizing medications)

Question 14

Rate limiting enzyme in PPP

Answer 14

Glucose-6-phosphate dehydrogenase

Question 15

Glutathione

Answer 15

In reduced form (GSH), protects against against hydrogen peroxide or other strong oxidizing agents
It protects hemoglobin and the cell membrane

Question 16

Non-oxidative phase of PPP

Answer 16

Known as the regenerative phase
Series of reversible steps
results in the production of two fructose-6-phosphates and one glyceraldehyde-3-phosphate

Question 17

Transketolase

Answer 17

Enzyme that requires thiamine (B1) as a coenzyme and catalyzes the transfer of 2 carbon segments

Question 18

Transaldolase

Answer 18

Enzyme that catalyzes the transfer of 3 carbon segments

Question 19

Heinz bodies

Answer 19

Denatured globin chains that precipitate with in RBCs s/p oxidative stress

Question 20

Bite cells

Answer 20

result from phagocytic removal of heniz bodys by splenic macrophages

Question 21

Respiratory burst

Answer 21

WBCs engaged in killing bacteria utilize NADPH in the respiratory burst response to invading organisms. this response produces oxygen freeradicals, which kill bacteria

Question 22

Allosteric inhibitors of PFK-1

Answer 22

ATP

Citrate

Question 23

Allosteric activators of PFK-1

Answer 23

AMP

Fructose-2,6-bisphosphate

Question 24

Allosteric inhibitors of Pyruvate Kinase

Answer 24

ATP

Alanine

Question 25

Allosteric activators of Pyruvate Kinase

Answer 25

Fructose-1,6-bisphosphate

Question 26

Primaquine

Answer 26

Treats malaria
Causes methemoglobinemia
G6PD deficient patients should not use this medication

Question 27

Rate limiting step

Answer 27

PFK 1

Question 28

Hexokinase inhibitor

Answer 28

Glucose 6 phosphate