Exam 15: Gene Mutation,dna Repair,and Transposition

A geneticist is studying a particular Drosophila mutant that produces a phenotype of "no wing" due to a mutation in a gene called wingless.She takes the mutant wingless and mutagenizes it.She hypothesizes that any fly that emerges with wings will be due to the original mutated gene reverting back to the wild- type allele. From this study,she identifies a fly that now has wings.When she sequences the wingless gene,she discovers that the original mutation is still there,and there are no other mutations in the wingless gene.However,a second gene at a separate locus is mutated.The second mutation is best classified as an__________.

Adenine methylase is an enzyme used during mismatch repair MMR).It helps determine which strand needs to be repaired by discriminating between template and new DNA strand.If this enzyme is mutated,how would MMR be affected?

How were insertion sequences IS elements)first discovered?

Compare and contrast between the following types of mutations: missense,nonsense,silent,and neutral.

DNA may be damaged from the by- products of normal cellular aerobic respiration.Name three of these electrophilic oxidants that are generally classified as reactive oxidants.

Some bacterial transposons,known as Tn elements,are larger than insertion sequences IS elements)and contain protein- coding genes that have human health significance.What might such a bacterial transposon contain?

What are LINES?

A heterozygote could have a variety of phenotypes depending on whether or not the mutation is recessive,dominant,or haploinsufficient.In this example,the gene A is necessary to form a tail in mice.If the mouse is a heterozygote A/a),then what would you predict the phenotype to be if the mutation was recessive,dominant,or haploinsufficient.

All insertion sequences IS elements)contain two structural elements that are essential for their movement.What are these two elements?

Which repair mechanism is most likely affected if the enzyme DNA glycosylase is not functioning properly?

Three major types of RNAs are mRNA,rRNA,and tRNA.For each of the conditions below,predict the conseque terms of the population of proteins being synthesized in a particular cell.What qualitative and quantitative chan any,are expected in the individual protein involved if one is involved)and in the population of proteins produc that cell? a)A frameshift mutation in mRNA.The condition is heterozygous in the involved cell. b)A deletion homozygous)that removes approximately half of the rRNA genes.

In World War I,mustard gas was used as a chemical weapon,and at a high dose,it would cause death. However,it is now known to be a chemical mutagen.Explain how those who came in contact with mustard gas and survived have an increase chance of developing mutations.

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

Which of the following diseases are caused by an expansion of trinucleotide repeats?

Barbara McClintock discovered mobile elements in corn by analyzing the genetic behavior of two elements,Ds and Ac.The interplay between these two elements has become one of the most interesting stories of discovery in the field of genetics.How do Ds and Ac interact?

What is meant by the term photoreactivation repair?

Describe the action of the enzyme transposase.

Ultraviolet light causes pyrimidine dimers to form in DNA.Some individuals are genetically incapable of repairing some dimers at "normal" rates.Such individuals are likely to suffer from__________ .

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.

From the Luria- Delbruck fluctuation test,when would mutations arise in yeast cells to allow for survival in the presence of toxic levels of hydrogen peroxide?