Haemoglobin synthesis stas with?
**Core Concept**
Haemoglobin synthesis is a complex process involving multiple steps and enzymes, ultimately leading to the production of a functional haemoglobin molecule. This process begins with the synthesis of a key precursor molecule, which serves as the foundation for subsequent steps.
**Why the Correct Answer is Right**
Haemoglobin synthesis starts with the synthesis of delta-aminolevulinic acid (ALA), which is formed from the condensation of glycine and succinyl-CoA. This reaction is catalyzed by the enzyme ALA synthase and marks the first step in the haem biosynthetic pathway. The subsequent steps involve the conversion of ALA to porphobilinogen, which is then processed into uroporphyrinogen, and eventually, haem is synthesized and incorporated into globin chains to form haemoglobin.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately represent the initial step in haemoglobin synthesis.
**Option B:** This option is incorrect because it is a later step in the haem biosynthetic pathway, not the starting point.
**Option C:** This option is incorrect because it refers to a different process altogether, unrelated to haemoglobin synthesis.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that defects in haem biosynthesis can lead to various disorders, including porphyrias, which are characterized by the accumulation of intermediate compounds in the pathway. Understanding the initial step in haemoglobin synthesis is crucial for appreciating these disorders.
**Correct Answer: C. Delta-aminolevulinic acid (ALA)**