4.1 ERYTHROCYTE METABOLISM

Question 1

Two sites on the Hgb molecule
which are prone to oxidation:

Answer 1

1. Iron atom (heme)
2. Sulfhydryl groups (globin)

Question 2

RBC relies on________________ for its energy.

Answer 2

anaerobic glycolysis

Question 3

❖ RBC metabolic processes requiring energy:

Answer 3

 Intracellular cationic gradient maintenance
 Maintenance of membrane phospholipid distribution
 Maintenance of skeletal protein deformability
 Maintenance of functional hemoglobin with ferrous iron
 Protecting cell proteins from oxidative denaturation
 Glycolysis initiation and maintenance
 Glutathione synthesis
 Nucleotide salvage reactions

Question 4

principal source of energy

Answer 4

Glucose

Question 5

Other sources of energy

Answer 5

galactose, fructose, and mannose

Question 6

RBC membrane is permeable to what energy sources

Answer 6

glucose

Question 7

RBC membrane is NOT permeable to what energy sources

Answer 7

sucrose, lactose, and maltose

Question 8

90-95 % of glucose – metabolized by the

Answer 8

Embden-Meyerhof pathway (EMP)

Question 9

5-10 % of glucose – metabolized by the

Answer 9

Hexose Monophosphate Shunt (HMP)/Pentose Phosphate Shunt
(PPS)

Question 10

 Major source of RBC energy | 90% Anaerobic glycolysis
 Requires glucose for energy production

Answer 10

Embden-Meyerhof Pathway

Question 11

Embden-Meyerhof Pathway Maintains cellular energy by generating

Answer 11

2 ATP molecules

Question 12

most common deficiency in the E-M pathway

Answer 12

PK (pyruvate kinase) deficiency

Question 13

Rate of glycolysis ↑ when there is

Answer 13

↑ in the intracellular pH (hypoxia)

Question 14

Rate of glycolysis ↓ when

Answer 14

ATP levels ↑ and
vice versa

Question 15

 Maintains membrane proteins & lipids, enzymes, hemoglobin iron in its ferrous state
 Prevents denaturation of Hb molecule by oxidation

Answer 15

Hexose Monophosphate Shunt/ Oxidative Pathway/
Pentose-Phosphate Pathway

Question 16

What enzyme in the Hexose Monophosphate Shunt reduces NADP to NADPH?

Answer 16

G6PD (Glucose-6-phosphate dehydrogenase)

Question 17

What is the primary function of the Hexose Monophosphate Shunt/Pentose Phosphate Pathway in red blood cells?

Answer 17

Maintains membrane proteins, lipids, enzymes, and hemoglobin iron in its ferrous state.

Question 18

Reduces toxic peroxide to water and oxygen, protecting hemoglobin from oxidation

Answer 18

reduced glutathione (GSH)

Question 19

Which enzyme is responsible for converting oxidized glutathione (GSSG) to reduced glutathione (GSH)?

Answer 19

Glutathione reductase

Question 20

What condition results from a G6PD deficiency and leads to the formation of denatured globins?

Answer 20

Heinz bodies

Question 21

What is the toxic effect of peroxide in red blood cells?

Answer 21

It oxidizes hemoglobin iron from Fe2+ to Fe3+, damaging the globin proteins.

Question 22

provides the only means
of generating NADPH.

Answer 22

G6PD

Question 23

oxidized heme unable to carry O2

Answer 23

methemoglobin

Question 24

Maintenance of the iron in its FERROUS state by which enzymes

Answer 24

methemoglobin reductase/cytochrome
b5 reductase

Question 25

in the presence of methemoglobin reductase converts ferric iron → ferrous iron

Answer 25

NADPH

Question 26

Generates 2,3 DPG w/c regulates O2 delivery to tissues by competing w/ O2 for the O2 binding site of Hb

Answer 26

Rapoport-Luebering Pathway

Question 27

↑ 2,3-BPG: ↓ Hb affinity to O2 →

Answer 27

↑ Tissue oxygenation

Question 28

↓ 2,3-BPG: ↑ Hb affinity to O2 →

Answer 28

↓ Tissue oxygenation