Question

if part of the dna gene being transcribed is tgc aat, what will the mrna code be for that part?

• ucgttu

• acguua

• ugcaau

• tgcaat

Explanation:

To determine the mRNA code from a DNA sequence, we use the base - pairing rules for transcription. In DNA, the bases are adenine (A), thymine (T), cytosine (C), and guanine (G). During transcription, DNA is used as a template to make mRNA. The base - pairing rules for transcription are: adenine (A) in DNA pairs with uracil (U) in mRNA, thymine (T) in DNA pairs with adenine (A) in mRNA, cytosine (C) in DNA pairs with guanine (G) in mRNA, and guanine (G) in DNA pairs with cytosine (C) in mRNA.

Let's analyze the given DNA sequence "TGCAAT" base by base:

• The first base in DNA is T. According to the rules, T pairs with A in mRNA.
• The second base in DNA is G. G pairs with C in mRNA.
• The third base in DNA is C. C pairs with G in mRNA.
• The fourth base in DNA is A. A pairs with U in mRNA.
• The fifth base in DNA is A. A pairs with U in mRNA.
• The sixth base in DNA is T. T pairs with A in mRNA.

Putting these paired bases together, we get the mRNA sequence "ACGUUA".

Now let's check the other options:

• Option "UCGTTU": The base - pairing is incorrect. For example, the first base T in DNA should pair with A, not U.
• Option "UGCAAU": The base - pairing for the first few bases is wrong. T in DNA should pair with A, not U.
• Option "TGCAAT": This is the same as the DNA sequence, but mRNA does not contain thymine (T), so this is incorrect.

Answer:

B. ACGUUA