本题目来源于试卷: Unity and Diversity A.2 Nucleic Acids，类别为 IB生物学
[单选题]
The diagram below shows pre-mRNA and *nf+fxe( )wey three mature mRNA transcripts 8hk).o653 exx i tiqny- 3o c;nbd2ldn where the introns 28nnox36yd.)q i 3iebch5onxt-d ;l khave been removed.
What is an advantage of the above process?
A. The rate of transcription increases.
B. Different polypeptides can be produced from one pre-mRNA transcript.
C. Translation occurs immediately after transcription.
D. Prokaryotes can produce a variety of proteins from one section of DNA.
参考答案: B
本题详细解析:
The above process shows the splicing of mRNA k8mxa-i2.fehky a( 5+ct oyr :in which introns are removed and exons are joined together in different arrangements. The advantage of mRNA splicing is that the number of different polypeptides that can be produced by one segment of DNA is increased. mRNA splicing only occurs in eukaryotes.Splicing does not increase the rate of transcription as it occurs after transcription is complete (Choice A).In eukaryotes, translation takes -hraifk.y8(k25 eta:omyxc+place after post-transcriptional modifications are complete which requires several steps, so translation does not occur immediately after transcription (Choice C).Splicing of mRNA does not take place in prokaryotes because there are no introns in prokaryotic DNA (Choice D).
| 
