The given nucleotide sequence on mRNA is as shown below :
5' AUGUCAUGGGAGUGAGUUGGGCUAAAAUAG 3'
(A) How many amino acids will be inserted in a polypeptide chain under normal conditions?
(B) How many amino acids will be inserted in a polypeptide chain in a mutated situation by the deletion of 9th nucleotide in the cistron part of DNA ?

Options

A. (A) 4, (B) 9
B. (A) 4, (B) 7
C. (A) 6, (B) 8
D. (A) 5, (B) 7

Answer

To solve the problem, we will analyze the given mRNA sequence and determine the number of amino acids that will be inserted into a polypeptide chain under two different conditions: normal and mutated.

### Step-by-Step Solution

**Step 1: Identify the mRNA sequence.**
The given mRNA sequence is:
5' AUGUCAUGGGAGUGAGUUGGGCUAAAAUAG 3'

**Step 2: Divide the mRNA sequence into codons.**
Codons are groups of three nucleotides. We will divide the sequence into codons:
- AUG | UCA | UGG | GAG | UGA | GUU | GGC | UAA | UAG

**Step 3: Count the number of codons.**
From the division, we can see that there are 9 codons in total.

**Step 4: Identify the stop codons.**
The stop codons are UAA, UGA, and UAG. In our sequence, UGA and UAA are present. When a stop codon is reached, the synthesis of the polypeptide chain stops.

**Step 5: Determine the number of amino acids in normal conditions.**
- The first codon (AUG) is a start codon and codes for Methionine (1 amino acid).
- The second codon (UCA) codes for Serine (2 amino acids).
- The third codon (UGG) codes for Tryptophan (3 amino acids).
- The fourth codon (GAG) codes for Glutamic acid (4 amino acids).
- The fifth codon (UGA) is a stop codon.

Thus, the synthesis stops after the fourth amino acid. Therefore, under normal conditions, **4 amino acids** will be inserted into the polypeptide chain.

**Step 6: Analyze the mutated situation.**
In the mutated situation, the 9th nucleotide is deleted. The original sequence of codons is:
- AUG | UCA | UGG | GAG | UGA | GUU | GGC | UAA | UAG

If we delete the 9th nucleotide (which is the first 'G' in UGA), the new sequence becomes:
- AUG | UCA | UGG | GAG | UGU | GGC | UAA

**Step 7: Count the new codons.**
Now, we have:
- AUG (Methionine)
- UCA (Serine)
- UGG (Tryptophan)
- GAG (Glutamic acid)
- UGU (Cysteine)
- GGC (Glycine)
- UAA (Stop codon)

**Step 8: Determine the number of amino acids in the mutated situation.**
In this case, the synthesis will stop after the sixth codon (UAA). Therefore, under the mutated condition, **6 amino acids** will be inserted into the polypeptide chain.

### Final Answers
(A) Under normal conditions, 4 amino acids will be inserted.
(B) In the mutated situation, 6 amino acids will be inserted.