Foetal haemoglobin is

Options

A. `zeta_(2)gamma_(2)`
B. `alpha_(2)epsi_(2)`
C. `alpha_(2)gamma_(2)`
D. `alpha_(2)epsi_(2)`.

Answer

**Step-by-Step Text Solution:**

1. **Understanding Fetal Hemoglobin (HbF):**
- Fetal hemoglobin is the main oxygen-carrying protein found in the red blood cells of a developing fetus. It is crucial for transporting oxygen from the mother’s bloodstream to the fetus's organs and tissues.

2. **Composition of Fetal Hemoglobin:**
- Fetal hemoglobin (HbF) is composed of two alpha (α) subunits and two gamma (γ) subunits. Therefore, its structure can be represented as α2γ2.

3. **Comparison with Adult Hemoglobin:**
- In contrast, adult hemoglobin (HbA) is composed of two alpha (α) subunits and two beta (β) subunits, represented as α2β2. This distinction is important for understanding the differences in oxygen affinity between fetal and adult hemoglobin.

4. **Presence of Fetal Hemoglobin:**
- At birth, fetal hemoglobin constitutes about 65% to 90% of the total hemoglobin in the fetus. By the age of 6 to 12 months, the levels of fetal hemoglobin typically drop to less than 2%.

5. **Genetic Encoding:**
- The alpha subunit of fetal hemoglobin is encoded on chromosome 16, while the gamma subunit is encoded on chromosome 11. This genetic information is vital for the production of hemoglobin in the fetus.

6. **Identifying the Correct Option:**
- Given the options provided in the question, the correct composition of fetal hemoglobin is α2γ2, which corresponds to the third option. The other options either incorrectly mention the presence of beta or epsilon subunits, which are not part of fetal hemoglobin.

**Final Answer:**
- The correct answer is: **Alpha 2 and Gamma 2 (α2γ2)**.

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