Question textConsider the codon table below for this question.Below is the Wildtype version (WT) of the coding region of an mRNA including a portion of the 3’ untranslated region (UTR), with its resulting amino acid sequence above it. You have discovered a mutant version (M) of the gene. Met Thr Ser Arg Thr TyrWT 5’-GGC CCA AUG ACG UCA AGA ACC UAU UAA GAU… 3’ UTR continuesM 5’-GGC CCA AUG ACG UAA AGA ACC UAU UAA GAU… 3’ UTR continuesa) What change has occurred in the mutant sequence? Answer 1 Question 9[select: , Nucleotide substitution(s), Nucleotide insertion(s), Nucleotide deletion(s), Nucleotide fragmentation(s)]b) What type of mutation has this caused? Answer 2 Question 9[select: , Frameshift mutation, Missense mutation, In-frame deletion, Silent mutation, In-frame insertion, Nonsense mutation]

Question

BlackTom AI · Accepted Answer

To tackle this question, I’ll compare the wildtype (WT) coding sequence with the mutant (M) sequence and examine how a single change affects the codons and the resulting protein.
Option a) Nucleotide substitution(s) vs the other possibilities:
- In the WT sequence, the codon at the fifth position is UCA (which encodes Ser). In the mutant, that same region is UAA (which encodes a Stop). This is a single-nucleotide change within the codon (UCA → UAA), not an insertion or a deletion of nucleotides, and there is no fragmentation of the sequence. Therefore, the alteration is best described as a nucleotide substitution(s).
- If it were an insertion, deletion, or fragmentation, you would expect a shift in the reading frame or a partial shift in codon boundaries, which is not indicated here since the rest of the sequence remains in-frame with the same codon boundaries after the change. Hence, the other options (insertion, deletion, fragmentation) do not fit.
Option b) Types of mutation (Frame shift, Missense, In-frame deletion, Silent, In-frame insertion, Nonsense):
- Frameshift mutation would require an insertion or deletion that shifts the reading frame, altering downstream codons. Here, only one codon changed from UCA to UAA without changing the downstream frame, so a frameshift is not correct.
- Missense mutation is when a codon change results in a different amino acid; here, the codon changes to UAA, which is a Stop codon, so it is not a missense mutation.
- In-frame deletion or insertion would alter amino acids within the same frame without introducing a Stop codon in the early region; the presence of a Stop codon at this position argues against in-frame indels.
- Silent mutation would mean the codon change does not alter the amino acid; since UCA encodes Ser and UAA encodes Stop, the amino acid sequence is affected (and is truncated by a Stop), so it cannot be silent.
- Nonsense mutation is defined as a single-nucleotide change that converts a sense codon into a Stop codon, resulting in premature termination of translation. This precisely describes the observed change from Ser (UCA) to Stop (UAA) at that position.

In summary, the observed change is a nucleotide substitution that converts a sense codon to a Stop codon, i.e., a nonsense mutation.

查看解析

登录即可查看完整答案

类似问题

What type of point mutation leads to the introduction of a stop codon in mRNA sequence?

Production of truncated proteins is commonly caused by which type of mutation?

A _________ mutation changes a codon that specifies an amino acid into one that terminates translation.

What type of point mutation leads to the introduction of a stop codon in mRNA sequence?

What is the result of a nonsense mutation in a coding sequence?

In a consumer society, many adults channel creativity into buying things

Economic stress and unpredictable times have resulted in a booming industry for self-help products

People born without creativity never can develop it

更多留学生实用工具

考试浏览器助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单