Which of the following statements are true of all t-RNAs?
1. The 5'end has guanine residue
2. They are single chains.
3. The anticodon loop is identical.
4. The 3'-end base sequence is CCA.
Select the correct answer using the codes given below:-
Codes:-

Options

A. 1,2 and 3
B. 1,3 and 4
C. 1,2 and 4
D. 2,3 and 4

Answer

To determine which statements are true for all t-RNAs, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement 1: The 5' end has a guanine residue.**
- **Analysis:** Most t-RNAs do have a guanine at the 5' end, but it is not universally true for all t-RNAs. Some t-RNAs can have other nucleotides at the 5' end.
- **Conclusion:** This statement is **False**.

2. **Statement 2: They are single chains.**
- **Analysis:** t-RNAs are indeed single-stranded molecules; however, they fold into a specific three-dimensional structure due to base pairing within the strand.
- **Conclusion:** This statement is **True**.

3. **Statement 3: The anticodon loop is identical.**
- **Analysis:** The anticodon loop is not identical across all t-RNAs. Each t-RNA has a unique anticodon that corresponds to a specific codon on the mRNA.
- **Conclusion:** This statement is **False**.

4. **Statement 4: The 3'-end base sequence is CCA.**
- **Analysis:** The 3' end of all t-RNAs has a CCA sequence, which is crucial for the attachment of the amino acid.
- **Conclusion:** This statement is **True**.

### Final Evaluation:
- True Statements: 2 and 4
- False Statements: 1 and 3

### Correct Answer:
Based on the analysis, the correct answer would be the codes for the true statements, which are 2 and 4.