1. Imagine a genomic researcher who is analyzing the genome of different types o
ID: 272384 • Letter: 1
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1. Imagine a genomic researcher who is analyzing the genome of different types of cats. She finds that a particular sequence in the North American Bobcat genome is exactly identical to a sequence found in the common house cat, while most other sequences in those two genomes differ at many nucleotides. (The most recent common ancestor between bobcats and house cats is estimated to be about 6.8 million years, plenty of time for mutation to generate DNA sequence variation.) Which of the following could explain the identical sequence in these otherwise differing genomes? (Select all that apply.) The sequence encodes a gene that is critical for life and cannot be easily mutated while retaining function. The sequence is contained in a retrovirus that has infected both species. The sequence encodes a protein critical for the production of fur color The sequence is from an intron of a gene that encodes a muscle protein 2. When an open reading frame (ORF) is identified, it may not actually correspond to the amino acid sequence of any polypeptide in the cell. Why not? (Select all that apply.) The amino acid sequence may not match any known sequence. It may contain one or more stop codons in the middle. The DNA may The ORF could be due to chance. not be transcribed into RNAExplanation / Answer
Answer 1. The correct option is A. The sequence encodes a gene that is critical for life and cannot be easily mutated while retaining function. Other options are not correct as retrovirus intergrated in the genome undergoes changes a lot as it is a part of endogenous retrovirus sequence and is a type of a transposon. Fur color is not a trait necessary for life and intron sequence do not code for muscle proteins or any proteins necessary for evolutionary purposes for that matter.
Answer 2. The correct options are A and B. In Eukaryotic genes that have multiple exons, ORF contains both introns and exons and multiple stop codons for multiple exons and this is why it may not match any known sequence.
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