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A part of an mRNA molecule with the sequence 5'-UGC-GCA-3' is being read by a ribosome. The charged transfer RNA molecules shown below, with their anticodons in the 3' to 5' direction, are available. Two of them can correctly match the mRNA so that a dipeptide can form:

| tRNA Anticodon | Amino Acid |
|----------------|------------|
| GGC | Proline |
| CGU | Alanine |
| UGC | Threonine |
| CCG | Glycine |
| ACG | Cysteine |
| CGG | Alanine |

Which of the following dipeptides will be formed?

A. Proline-Threonine
B. Glycine-Cysteine
C. Alanine-Alanine
D. Cysteine-Alanine



Answer :

GinnyAnswer
To determine which dipeptide will form, we need to follow these steps:

1. Identify the mRNA sequence: The given mRNA sequence is 5’-UGC-GCA-3’.

2. Determine the corresponding tRNA anticodons: To match the mRNA codons with the tRNA anticodons, we need to find the anticodons that are complementary to the mRNA codons.

- The first mRNA codon is UGC.
- The complementary tRNA anticodon for UGC is ACG (since A pairs with U, C pairs with G, and G pairs with C).

- The second mRNA codon is GCA.
- The complementary tRNA anticodon for GCA is CGU (since C pairs with G, G pairs with C, and U pairs with A).

3. Find the corresponding amino acids: Next, we use the tRNA anticodons to find the corresponding amino acids based on the provided table.

- The anticodon ACG corresponds to the amino acid Cysteine.
- The anticodon CGU corresponds to the amino acid Alanine.

4. Form the dipeptide: By combining the amino acids decoded from the mRNA sequence, we can form the dipeptide.

- The first amino acid is Cysteine.
- The second amino acid is Alanine.
- Therefore, the dipeptide formed is Cysteine-Alanine.

Thus, the correct dipeptide that will be formed is Cysteine-Alanine.

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