DrVirgo
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48. The nucleotide sequence encoding four amino acids near the amino terminus of a 10- kd protein is 5´- ACT GAT TGC GTT -3´. This sequence is mutated by insertion of a single nucleotide (A) in the second codon and becomes 5´- ACT GAA TTG CGT -3´. Which of the following consequences of this mutation is most likely?
A ) Altered cell-cycle checkpoint
B ) Decreased rate of transcription
C ) Protein truncation
D ) Single amino acid substitution
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| nadiabarati
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it's a frameshift mutation. So we will have altered codons and therefore aminoacids from the insertion till the end. I'm just wondering that protein truncation occur when a single base substitution changes a codon for a termination codon so after that point translation would atop and the result would be a truncation protein....
but still C seems the correct answer!
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| doc179
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C
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| DrVirgo
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Am i missing something... I guess the other choices don't make sense, but: How is it truncation?
Please explain....
Edited by DrVirgo on 02/22/06 - 06:50 AM
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| sturge_weber
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any change in the sequence of the codons will lead to truncation ultimately... so c...
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| DrVirgo
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Yes, thats true. You all are right.
Just for the sake of discussion, what if the single base addition or deletion leads to the loss of a stop codon?
Would the protein end up being longer than normal?
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| doc179
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well if it ends up in the loss of a stop codon then I think the protein should be longer than normal
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