Question

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 from an intron of a gene that encodes a muscle protein. The sequence encodes a protein critical for the production of fur color. The sequence is contained in a retrovirus that has infected both species.

Answer 1

Answers:

1. The sequence encodes a gene that is critical for life and cannot be easily mutated while retaining function.
2. The sequence is contained in a retrovirus that has infected both species.

1- Explanation:

6.8 million years is a considerable period of time and if the cats were evolved in two different specie then technically they should have substantially different sequences of gene. However, there are some genes that are critical for the survival of the organisms because they encode a function which is equally important for the organisms of a certain category, even if they are different specie.

For example, the essential genes that are involved in maintenance of metabolism, initiation of replication or translation of genes. Therefore, with the period of time, the mutation of even a single nucleotide can be lethal for these genes, and if it happens organism will simply die. So, if one organisms is died that cannot take part in the process of evolution and would clearly be cut off from the process, However, those who survive can undergo some other mutations and become separate specie.

2- Explanation:

A retro virus inserts itself in to the genome of host organisms and become a part of them. It is very difficult to detect the presence of the retro virus until the organism undergoes infection due to its attack. Cats are a favorable host for retroviruses - called lentiviruses which attack the cats to cause a critical syndrome Feline Immunodeficiency Virus or FIV. Therefore, it is possible that same retrovirus having a particular sequence has attacked both cats and the sequences were taken from those cats.

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