Question

Why are base sequences of mRNA and the DNA non-template strand not identical?

a) mRNA undergoes splicing
b) Different codon usage
c) Incomplete transcription
d) Genetic mutations

Answer 1

The base sequences of mRNA and the DNA non-template strand are not identical due to splicing, different codon usage, and genetic mutations.

Step-by-step explanation:

The base sequences of mRNA and the DNA non-template strand are not identical due to several reasons:

1. mRNA undergoes splicing: After transcription, mRNA undergoes a process called splicing, where non-coding regions known as introns are removed and the remaining coding regions, known as exons, are joined together. This process results in mRNA sequences that are different from the DNA non-template strand.
2. Different codon usage: While mRNA is complementary to the DNA template strand, it uses different codons to specify amino acids. This means that the base sequences of mRNA and the DNA non-template strand will not be identical.
3. Genetic mutations: Mutations can occur in the DNA template strand, which can lead to changes in the base sequence of the mRNA. These mutations can introduce differences between the two sequences.

It is important to note that while the base sequences of mRNA and the DNA non-template strand are not identical, they are still complementary.