reet
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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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| doc179
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is it D?
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| reet
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yes,, i too think so D. CUZ third position only changed.
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| msyamp
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no doc and reet. it is a frameshift mutation guys. answer is protein trunkation. see that all the triplets are changed so aminoacids are changed. your is correct if there is a single aminacid SUBSTITUTION then it would be ok.
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| reet
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THANKS msyamp.. i dont know wht would happen to genetics in my exam...
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| msyamp
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dont worry. work it out just like the metabolism parts . you can do it. see the line below
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| doc179
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oh yes...you are right...I was not attentive enough..I should not be like this in the exam
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| Cedrick
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Protein trucation
C
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| Musuq
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Frameshift mutations are caused by INSERTION or DELETION of any number of nucleotides not divisible by 3, which shifts the reading frame during translation of mRNA.
A framsehift mutation results in a randomly incorrect amino acid sequence on the carboxyl side of the mutation and usually a truncated protein caused by the introduction of apremature stop codon.
Ex: TAY-SACHS disease is the result of a 4 nucleotide insertion that causes a frameshift mutation and defective Hexosaminidase.
Without Hex-A, a fatty substance or lipid called GM2 ganglioside accumulates abnormally in cells, especially in the nerve cells of the brain. This ongoing accumulation causes progressive damage to the cells. The destructive process begins in the fetus early in pregnancy, although the disease is not clinically apparent until the child is several months old. By the time a child with TSD is three or four years old, the nervous system is so badly affected that life itself cannot be supported.
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| vallia
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thanks, good review
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