What would be the complementary mRNA strand to the following strand of DNA?
CAGGCTAAG
A.
GTCGATTC
B.
GACCGTAAC
C.
GUCGAUUC
D.
CAGGCTAAG
The Correct Answer and Explanation is:
To determine the complementary mRNA strand to the given DNA sequence (CAGGCTAAG), we need to first understand how DNA and mRNA base pairing works. DNA consists of four nucleotides represented by the letters A (adenine), T (thymine), C (cytosine), and G (guanine). In DNA, adenine pairs with thymine, and cytosine pairs with guanine.
When transcribing DNA to mRNA, the base pairing rules change slightly. In RNA, the nucleotide uracil (U) replaces thymine (T). Thus, adenine in the DNA will pair with uracil in the mRNA. The complementary pairs will be as follows:
- A (adenine) pairs with U (uracil)
- T (thymine) pairs with A (adenine)
- C (cytosine) pairs with G (guanine)
- G (guanine) pairs with C (cytosine)
Now, let’s transcribe the provided DNA strand (CAGGCTAAG) to its complementary mRNA strand:
- C (cytosine) → G (guanine)
- A (adenine) → U (uracil)
- G (guanine) → C (cytosine)
- G (guanine) → C (cytosine)
- C (cytosine) → G (guanine)
- T (thymine) → A (adenine)
- A (adenine) → U (uracil)
- A (adenine) → U (uracil)
- G (guanine) → C (cytosine)
Putting it all together, the complementary mRNA strand becomes GUC CGA UUC.
Now let’s match this result with the provided answer choices:
A. GTCGATTC
B. GACCGTAAC
C. GUCGAUUC
D. CAGGCTAAG
The correct answer is C. GUCGAUUC.
This strand accurately represents the complementary sequence based on the rules of RNA transcription from DNA. Understanding the transcription process is crucial in genetics, molecular biology, and biotechnology, as it forms the basis for protein synthesis and gene expression.