Exam 14: Gene Mutation,DNA Repair,and Transposition

Describe the mutagenic action of the following two mutagens: 5-bromouracil and ultraviolet light.

Two formal terms used to describe categories of mutational nucleotide substitutions in DNA are ________.

Which human condition is caused by unrepaired UV-induced lesions?

Pyrimidine dimers are typically caused by the mutagen 2-amino purine.

The shorter the wavelength of a radiation source,the greater its likelihood of causing damage.

Three human disorders-fragile-X syndrome,myotonic dystrophy,and Huntington disease-are conceptually linked by a common mode of molecular upset.Describe the phenomena that link these disorders.

Although mutation is the original source of genetic variation,its influence on changing allelic frequencies is relatively minor.

Transposons,or jumping genes,are DNA elements that move within the genome.In which organismic groups are transposons found?

Of the two cell lines that can contain a mutation in an organism,somatic line and germ line,the latter is more consequential to subsequent generations.

Strand discrimination during the process of DNA repair is based on DNA methylation in E.coli.

IS elements (insertion sequences)are stable DNA occupants of prokaryotic genomes that are not found among eukaryotes.

A class of mutations that results in multiple contiguous amino acid changes in proteins is likely to be which of the following?

Loss-of-function mutations eliminate the function of a gene product and may be dominant or recessive.

Mutations that arise in nature,from no particular artificial agent,are called ________.

Certain base analogs such as 5-bromouracil cause mutations by chemically altering nitrogenous bases in nonreplicating DNA.

What is the common influence of ultraviolet light on DNA?

In general,mutation rates in humans occur in the range of ________ (frequency)per gamete per generation.

Some mutagens cause genetic changes that can be "corrected" by reexposing cells to the same mutagen.Other mutagens do not behave in this way.Provide one example of each of these two types of agents and describe the mutational changes caused in DNA.Explain why some mutagens behave in one way,whereas others do not.

What is the Ames test,and how does it work?

When X-rays penetrate cells,electrons are ejected from atoms of molecules.Stable molecules can be transformed into which two types of hazardous materials?