If one strand of DNA has the base sequence ATCCACGACTAG and the second strand undergoes transcription what would be the base sequence on mRNA ?

Options

A. TUACCTUAUTGG
B. TACGTGCTGATC
C. ATCCACGACTAG
D. AUCCACGACUAG

Answer

To determine the base sequence of mRNA from a given DNA strand, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the DNA Strand**: The given DNA sequence is ATCCACGACTAG. This sequence represents one of the strands of DNA.

2. **Determine the Complementary Strand**: The complementary base pairing rules in DNA 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)

Therefore, the complementary strand to ATCCACGACTAG would be:
- A -> T
- T -> A
- C -> G
- C -> G
- A -> T
- C -> G
- G -> C
- A -> T
- C -> G
- T -> A
- A -> T
- G -> C

This results in the complementary strand: TAGGTGCTGATC.

3. **Identify the Template Strand for Transcription**: In transcription, the template strand is used to synthesize mRNA. Here, we will assume that the complementary strand (TAGGTGCTGATC) is the template strand.

4. **Transcribe the Template Strand into mRNA**: During transcription, the base pairing rules change slightly:
- Adenine (A) pairs with Uracil (U) instead of Thymine (T)
- Thymine (T) pairs with Adenine (A)
- Cytosine (C) pairs with Guanine (G)
- Guanine (G) pairs with Cytosine (C)

Therefore, transcribing the template strand (TAGGTGCTGATC) to mRNA gives:
- T -> A
- A -> U
- G -> C
- G -> C
- T -> A
- G -> C
- C -> G
- T -> A
- G -> C
- A -> U
- T -> A
- C -> G

This results in the mRNA sequence: AUCCACGACUAG.

5. **Final Result**: The base sequence on the mRNA is AUCCACGACUAG.