The following sequence of DNA is the normal, wild-type gene. 5\' ATG C G G GTA G
ID: 174854 • Letter: T
Question
The following sequence of DNA is the normal, wild-type gene. 5' ATG CGG GTA GTT AGC CGA TAG 3' A deletion occurs during DNA replication, causing the guanine shown in bold to be removed from the nucleotide strand. What effect will this have on the final protein?
The deletion of the G will cause a frame shift, resulting in the loss of the normal stop codon and an abnormally long protein with an altered amino acid sequence.
The deletion of the G will not have an effect on the final protein.
The deletion of the G will cause a single amino acid substitution in the codon in which it occurs.
The deletion of the G will cause a frame shift, resulting in a premature stop codon and a truncated protein.
The deletion of the G will cause a frae shift, so that all the amino acids after the mutation will change.
The protein will be a normal number of amino acids.
Explanation / Answer
Answer : The correct answer is E (The deletion of the G will cause a frame shift, so that all the amino acids after the mutation will change)
Explanation : Frame shift mutations result from the insertion or deletion of one or more (not in multiples of three) nucleotides in the coding region of a gene. This cause an alteration of the reading frame: since codons are groups of three nucleotides, there are three possible reading frames for each gene although only one is used.
For example : mRNA with sequence AUG CAG AUA AAC GCU GCA UAA
amino acid sequence from the first reading frame: met gln ile asn ala ala stop
the second reading frame gives: cys, arg stop.
A mutation of this sort changes all the amino acids downstream and is very likely to create a nonfunctional product since it may differ greatly from the normal protein. Further, reading frames other than the correct one often contain stop codons which will truncate the mutant protein prematurely.