Author Question: What type of mutation does not change the amino acid sequence and thus has no observable ... (Read 143 times)

Pineappleeh · **on:** Jun 25, 2018

What type of mutation does not change the amino acid sequence and thus has no observable consequence?

a. Frameshift
b. Spontaneous
c. Silent
d. Missense

Question 2

A nurse is reviewing the pedigree chart. When checking for a proband, what is the nurse looking for?

a. The person who is first diagnosed with a genetic disease.
b. The individual who has a disease gene but is phenotypically normal.
c. The phenotype of genetic material.
d. The codominance.

nhea · **Reply #1 on:** Jun 25, 2018

Answer to Question 1

ANS: C
Silent mutations do not change the amino acid sequence and therefore have no consequences. Frameshift mutations involve the insertion or deletion of one or more base pairs of the DNA molecule. They alter the amino acid sequence. Spontaneous mutations occur in the absence of exposure to a mutagen and produce changes in the amino acid sequence. Missense mutations, a form of base pair substitution, alter amino acids, which produce a change (i.e., the sense) in a single amino acid.

Answer to Question 2

ANS: A
The pedigree chart summarizes family relationships and shows which members of a family are affected by a genetic disease. The pedigree begins with the proband. The person who has a dis-ease gene but is phenotypically normal is a carrier. The phenotype is the result of both genotype and environment; it is not a proband. Codominance is not represented by a proband, but it occurs when the heterozygote is distinguishable from both homozygotes.