How many nucleotides are used for the synthesis of A chain and B chain of insulin?

Options

A. 90 for A and 63 for B
B. 63 for A and 93 for B
C. 92 for A and 61 for B
D. 60 for A and 61 for B

Answer

To determine how many nucleotides are used for the synthesis of the A chain and B chain of insulin, we can follow these steps:

### Step 1: Understand the Structure of Insulin
Insulin is a protein composed of two chains: the A chain and the B chain. The total number of amino acids in insulin is 51, with the A chain consisting of 21 amino acids and the B chain consisting of 30 amino acids.

### Step 2: Calculate the Number of Nucleotides
Each amino acid is coded by a set of three nucleotides (codon) in the genetic code. Therefore, to find the number of nucleotides required for each chain, we can use the following formula:
- Number of nucleotides = Number of amino acids × 3

### Step 3: Calculate for the A Chain
For the A chain:
- Number of amino acids = 21
- Number of nucleotides = 21 amino acids × 3 nucleotides/amino acid = 63 nucleotides

### Step 4: Calculate for the B Chain
For the B chain:
- Number of amino acids = 30
- Number of nucleotides = 30 amino acids × 3 nucleotides/amino acid = 90 nucleotides

### Step 5: Summarize the Results
- A chain requires 63 nucleotides.
- B chain requires 90 nucleotides.

### Final Answer
- Total nucleotides for A chain = 63
- Total nucleotides for B chain = 90