Question

A transcription unit that is 8,000 nucleotides long may use 1,200 nucleotides to make a protein consisting of approximately 400 amino acids. This is best explained by the fact that
A) many noncoding stretches of nucleotides are present in mRNA.
B) there is redundancy and ambiguity in the genetic code.
C) many nucleotides are needed to code for each amino acid.
D) nucleotides break off and are lost during the transcription process.
E) there are termination exons near the beginning of mRNA.

Answer 1

Answer:

A) many noncoding stretches of nucleotides are present in mRNA.

Explanation:

A transcription unit in eukaryotes includes the region that code for mRNA extending from the 5' cap site to the 3' poly-A site. It also includes the controlling regions. The mRNA formed by transcription also has some non-coding intervening sequences. These are called introns. Introns are removed from the primary transcripts by the process of splicing that occurs after transcription.

Therefore, a transcription unit that is 8,000 nucleotides long may use only 1,200 nucleotides to code for a protein having 400 amino acids since the rest of the nucleotides are part of introns and are removed from mRNA after transcription.