Exam 15: Gene Mutation and Molecular Medicine

Refer to the table. A bacterial cell has been exposed to a powerful mutagen.In the table shown, a sequence from this cell is compared with the same sequence from its ancestral cell.Intervening sequences where the ancestral and descendant cells have identical sequences are represented by dots.In the mutated cell there have been ________ transition(s) and _______ transversion(s).

Tautomers are

Which disease would be most difficult to detect with standard pedigree analysis?

Describe the expected effects of a somatic cell mutation that results in the loss of function of a tumor suppressor gene.

An induced mutation must involve

Refer to the table. A bacterial cell has been exposed to a powerful mutagen.The chromosomal sequences of the ancestral cell and the descendant cell are shown.(The ellipses represent intervening sequences that are identical.) The sequences show that there have been _______ transitions and 1 transversion.

What is the natural function of restriction enzymes?

Prenatal screening for PKU usually involves examining

Which statement about DNA linkage analysis is false?

Mutations that are not due to the presence or activity of a mutagen are referred to as _______ mutations.

Which mutation requires that two homologous chromosomes break?

To test an individual's genotype for the sickle-cell mutation, a _______ test would use a probe for normal hemoglobin and a probe for the sickle-cell mutation.

Which mutation is least likely to be a frame-shift mutation?

DNA sequencing reveals a base change in a gene, but there is no effect upon the functional activity of the encoded protein.This mutation can be considered a(n) _______ mutation.

When a clinical _______ is identified that is linked to one gene, DNA analysis can identify the mutations in the gene that cause the abnormal protein function.

Refer to the figure, which shows the genetic code. Determine which of the following changes would lead to a nonsense mutation.Note that the sequences offered as choices are from the nontemplate DNA strand.

Transposons are

Which type of variation would be most detectable by gel electrophoresis if the differences in the DNA were between two recognition sites for a restriction enzyme?

Phenylketonuria (PKU) and Duchenne muscular dystrophy (DMD) are both molecular diseases that are caused by mutations in particular genes, yet PKU is easier to treat than muscular dystrophy.Why?

For which type of mutation would you most expect the phenotypic effects of the affected alleles to become worse in successive generations?