Leucine in one of three amino acids which are coded by 6 codons. The codons that code leucine are CUU, CUC, CUA, CUG, UUA, UUG How may minimum types of t RNA will be required for reading all codons of leucine ?

Options

A. 1
B. 2
C. 4
D. 6

Answer

To determine the minimum types of tRNA required for reading all codons of leucine, we can follow these steps:

### Step 1: Identify the Codons for Leucine
Leucine is coded by the following six codons:
- CUU
- CUC
- CUA
- CUG
- UUA
- UUG

### Step 2: Understand the Role of tRNA
Each tRNA molecule is specific to one amino acid and can recognize one or more codons that code for that amino acid. The key is to find out how many different tRNA molecules are needed to cover all the codons for leucine.

### Step 3: Analyze Codon Pairing
The codons for leucine can be grouped based on their similarities:
- CUU, CUC, CUA, CUG share the first two nucleotides "CU" and differ only in the third nucleotide.
- UUA and UUG share the first two nucleotides "UU" and differ only in the third nucleotide.

### Step 4: Determine the Minimum tRNA Types Required
1. **First Group (CUU, CUC, CUA, CUG)**: A single tRNA can recognize all four codons (CUU, CUC, CUA, CUG) due to the wobble hypothesis, which allows for flexibility in the third position of the codon.
2. **Second Group (UUA, UUG)**: A second tRNA can recognize both of these codons.

### Conclusion
Thus, a minimum of **2 types of tRNA** is required to read all six codons for leucine.

### Final Answer
The minimum types of tRNA required for reading all codons of leucine is **2**.

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