Question

GENETIC EXPERT

Select and support the most appropriate response, and explain why each of the incorrect statements is eliminate.

Sequencing of the human genome can reveal

A).mutations that do not alter phenotype.

B) mutations that do not alter genotype.

C)which tissues express a gene.

D) how many genes a person has.

E.)epigenetic effects.

Answer 1

Answer: (A) mutations that do not alter phenotype.

Explanation:

Because humans have such a large genome, roughly 75 new mutations accumulate per human individual per lifetime. Most of these are probably not deleterious. Many do not occur in protein coding regions (5% of the human DNA sequence) or, if they do, do not change the particular amino acid (synonymous substitutions).

DNA sequencing can help identify silent mutations.

Mutations results in the change in the composition of the DNA sequence, thus resulting in a change in genotype. So, (B) is not correct.

Expression of genes and tissue specific and cannot be revealed from DNA sequencing as all the cells of the body has same genotypes. Thus, option (C) is not correct.

Within the limits of today's technology, the human genome is as complete as it can be. Small gaps that are unrecoverable in any current sequencing method remain, amounting for about 1 percent of the gene-containing portion of the genome, or euchromatin. New technologies will have to be invented to obtain the sequence of these regions. Thus, present scenario does not allow us to know all the genes a person has. So, option (D) is not correct.

Epigenetics is the study of heritable changes in gene expression (active versus inactive genes) that do not involve changes to the underlying DNA sequence. This cannot be identified through DNA sequencing. So, option (E) is not correct.