In the base sequence of one strand of DNA is `CAT TAG CAT CAT GAC` what would be the base sequence of its complementary m-RNA

Options

A. (a) GUA GUA CUG AUG CUG
B. (b) AUG CUG CUG GUA CUG
C. (c) GUA AUC GUA GUA CUG
D. (d) GUC CUG CUG CUA CUU

Answer

To find the base sequence of the complementary mRNA from the given DNA sequence, we follow these steps:

### Step-by-Step Solution:

1. **Identify the DNA Sequence**: The given DNA sequence is `CAT TAG CAT CAT GAC`. This sequence is in the 5' to 3' direction.

2. **Understand Base Pairing Rules**: In DNA, the base pairing rules are:
- Adenine (A) pairs with Thymine (T)
- Thymine (T) pairs with Adenine (A)
- Cytosine (C) pairs with Guanine (G)
- Guanine (G) pairs with Cytosine (C)

However, when synthesizing mRNA from DNA, Thymine (T) is replaced by Uracil (U) in RNA.

3. **Transcribe the DNA to mRNA**: We will transcribe the DNA sequence to mRNA by replacing each base with its complementary base according to the rules above, keeping in mind that T is replaced by U:
- C → G
- A → U
- T → A
- G → C

4. **Transcribe Each Codon**:
- For `CAT`:
- C → G
- A → U
- T → A
- Result: `GUA`
- For `TAG`:
- T → A
- A → U
- G → C
- Result: `AUC`
- For `CAT`:
- C → G
- A → U
- T → A
- Result: `GUA`
- For `CAT`:
- C → G
- A → U
- T → A
- Result: `GUA`
- For `GAC`:
- G → C
- A → U
- C → G
- Result: `CUG`

5. **Combine the mRNA Codons**: Now, combine all the transcribed codons:
- mRNA sequence: `GUA AUC GUA GUA CUG`

6. **Final mRNA Sequence**: The final mRNA sequence is `GUA AUC GUA GUA CUG`.

### Answer:
The base sequence of the complementary mRNA is `GUA AUC GUA GUA CUG`.

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