Haemoglobin Structure, Synthesis and Iron Metabolism

Question 1

explain the structure of haemoglobin molecule

Answer 1

2 dissimilar pairs of polypeptide chains - each of them enclose an iron containing porphyrin ring called haem

Question 2

what are the three phases of haemoglobin formation

Answer 2

embryonic, foetal and adult

Question 3

what chromosomes are responsible for globin synthesis

Answer 3

11 + 16

Question 4

what globins are produced by the diff chromosomes

Answer 4

chromosome 11= epsilon, delta, gamma and beta

chromosome 16 = zeta and alpha

Question 5

what are the different types of haemoglobin

Answer 5

A, A2, F, Gower 1+2, Portland 1+2

Question 6

explain how haemoglobin is produced in embryo (5 and ^ weeks gestation)

Answer 6

embryo Hb is produced in yolk sac. 5weeks of gestation = zeta and epsilon chains are made n primitive erythroblasts alongside Gower 1&2, Portland 1&2

6 WEEKS = primitive erythroblasts synth alpha, beta and gamma globins

Question 7

explain how haemoglobin is produced in embryo (week 10-12 to late uterine life)

Answer 7

Hb is synth in the liver and spleen (foetal Hb and Hb A after some time).

later in uterine life the bone marrow takes over as the main site of synthesis , and the amount of Hb A produced increases over time . Hb A is produced in bone marrow erythroblasts + other minor Hbs

Question 8

what are the regular levels of Hb A, A2, in a normal healthy adult

Answer 8

Hb A - 97%
Hb A2 - 2.0-3.3%
HbF- 0.2-1%

Question 9

what % of Hb contains the body’s iron

Answer 9

65%
30% is stored as ferritin in the form hemosiderin in macrophages of bone marrow, liver + spleen.

Question 10

where is iron in muscles and cells

Answer 10

myoglobin in muscles, and cytochrome enzymes in cells

Question 11

what transfers iron in the body

Answer 11

transferrin

Question 12

how much iron is absorbed in body from diet

Answer 12

5-10% normally, but can increase to 20-30% in iron deficiency/pregnancy

Question 13

what releases haem iron from gut

Answer 13

haemoxgenase 1

Question 14

How is ferric iron converted into ferrous form

Answer 14

via enzyme ferroreductase in the gut

Question 15

describe the structure of haem

Answer 15

protoporphyrin ring with iron atom in middle.
the ring has 4 pyrrol groups that are connected via methane bridges (=C-)
hydrogen atoms
- hydrogen in pyrrole groups replaced by 4 methyl groups (CH3-), two vinyl (-C=CH2) and two propionic acid (-CH2-CH2-COOH) groups

Question 16

how is iron broken down

Answer 16

via macrophages of RE system-