Biochemistry

Question 1

what are properties of a mature RBC

Answer 1

Packed with haemoglobin (Hb)
No nucleus or mitochondria
No DNA/RNA, therefore no cell division

Question 2

what is the life span of a RBC

Answer 2

120 days

spleen removes old RBC from circulation

Question 3

what happens to old RBCs

Answer 3

recycled by phagocytic cells of the liver and spleen

Question 4

what is the RBC broken down to

Answer 4

Haemoglobin broken down to&raquo_space; amino acids

Haem group (minus iron) is converted to bilirubin

Iron binds to transferrin in the blood and is recycled

Question 5

where does bilirubin go

Answer 5

transported to the liver and secreted into bile

Bilirubin breakdown products colour urine and faeces

Question 6

what regulates erythrocyte production

Answer 6

erythropoietin (EPO) produced by the kidney

Question 7

what causes the kidney to release EPO

Answer 7

hypoxia

Question 8

what are the steps of erythropoiesis

Answer 8

1 - proerythroblast (derived from myeloid stem cells)
2 - polychromatic erythroblast (Hb appears in cytoplasm)
3 - orthochromatic erythroblast (nucleus shrinks, full complement of Hb in cytoplasm)
4 - erythroblast extrudes nucleus
5 - reticulocyte into circulation
6 - mature RBC/erythrocyte

Question 9

what is the structure of a RBC and why is it important

Answer 9

biconcave disc

• increases SA
• flexible membrane so cell can squeeze through capillaries
• decreased diffusion distance

Question 10

what is the percentage of what blood is composed of

Answer 10

55% plasma
1% platelets + WBC

40-50% RBC (in males)
36-46% RBC (in females)

Question 11

how is a RBC ion balance and cell volume regulated

Answer 11

energy-dependent Na+/K+ ATPases (‘the sodium pump’)

Question 12

through what route does a RBC do ATP synthesis

Answer 12

anaerobic glycolysis

no mitochondria so cannot do aerobic glycolysis

Question 13

what from glycolysis keeps iron in the Fe2+ state

Answer 13

NADH

Question 14

what release oxygen from haemoglobin when we move to a higher altitude

Answer 14

2,3 BPG (biphosphoglycerate)

Question 15

what is Glutathione

Answer 15

Tripeptide, consisting of glutamate, cysteine, and glycine

Question 16

what is the role of Glutathione

Answer 16

Reduced glutathione (GSH) combats oxidative stress
i.e. an antioxidant 

maintains normal reduced state in a cell

Question 17

what are free radicals

Answer 17

highly reactive molecules with unpaired electrons

Question 18

what would happen if we had excessive free radicals or inadequate antioxidants

Answer 18

damage of cellular structures and enzymes

Question 19

what is the importance of glutathione

Answer 19

helps protect against the toxic effects of reactive oxygen species (free radicals)

essential to de-toxify hydrogen peroxide

Question 20

what is needed to produce glutathione

Answer 20

NADPH from the pentose phosphate pathway

Question 21

how is CO2 carried to the lungs

Answer 21

1- Physically dissolved in solution (amount ∝ Pco2)

2 - Bound to Hb – carbamino-haemoglobin

3 - As bicarbonate ion – HCO3-

Question 22

how is the movement of CO2 facilitated

Answer 22

by carbonic anhydrase

Question 23

what is haemoglobin comprised of

Answer 23

4 globin (protein) sub-units, each containing a single haem molecule

Question 24

what does each haem molecule contain

Answer 24

single Fe2+ ion

porphyrin ring

Question 25

what can each haem group bind too

Answer 25

one O2 molecule

Question 26

what does haemoglobin synthesis require

Answer 26

synthesis of globin chains – 4 per molecule of Hb

synthesis of porphyrin ring (haem group)

insertion of iron (Fe2+) into haem

Question 27

what are normal haemoglobin concentration

Answer 27

male = 130-180

female = 115-165

Question 28

how does foetal Hb differ from adult

Answer 28

has a higher affinity for O2

has a lower affinity for 2.3 BPG

facilitates the transfer of O2 from the mother to the foetus