BIOL479 Lecture Notes - Lecture 7: Mutation Rate, Pyrimidine, Purine

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coffeegnat887

3 Feb 2016

School

University of Waterloo

Department

Biology

Course

BIOL479

Professor

Jonathan Witt

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Document Summary

Def: any heritable change in dna sequence, or dna compliment (e. g. # of chromosomes) Ultimate source of all variation within pop. Mutations in somatic cells (e. g. your arm) that are not heritable, and hence are of no evolutionary consequence. Occur in gametes or the cells that produce them and can be passed on to offspring. Changes in the # or structure of chromosomes. Change of a single nucleotide in an dna sequence. E. g. transition: substitution of a purine (ag) w/ a purine or pyrimidine (cg) w/ a pyrimidine. E. g. transversion: substitution of a purine w/ a pyrimidine and vice versa. Transition are much more common than transversions, even though there are twice as many ways that transversions can occur. E. g. silent mutation (synonymous) do not change the a. a in a protein sequence. In coding regions, they can disrupt the reading frame and be highly deleterious. Genes, groups of genes or pieces of a chromosome can duplicate.

Related Questions

1).Which of the following demonstrates the importance of mutation?

A.Mutation is the ultimate source of genetic variation and thus is the foundation of why people are interested in genetics in the first place.

B.Mutation will remove variation from the population.

C.Mutations are always beneficial and thus allow organisms to adapt.

D.Mutation is detrimental to the population and thus is important only because we need to get rid of mechanisms that induce mutations.

E.Mutation is not important.

2).While the SOS repair pathway can repair devastating pyrimidine dimers, it comes at a cost. Which of the following best explains the cost of repairing DNA via the SOS repair pathway?

A.The other strand of DNA is used as a template to repair the damaged strand of DNA.

B.A nucleotide is removed so that DNA polymerase III can move past the pyrimidine dimer.

C.SOS will help DNA replication bypass pyrimidine dimers but will do so by using random nucleotides in place of the lesion.

D.The SOS repair pathway uses analogs in place of nucleotides when repairing damaged DNA.

3.Suppose you have two species of corn. One has sweet kernels and the other has large ears. Both have 20 chromosomes, each of which is homologous in both species. Suppose you want to create a hybrid that has both characteristics of sweet kernels and large ears, so you cross individuals from the two species. The initial hybrid you obtain has 20 chromosomes, but then you establish a viable tetraploid (4n) individual with 40 chromosomes. Which of the following could best explain this observation?

A.		Nondisjunction of a single chromosome caused the doubling of the genome.
		B.The initial F1 hybrid was unable to produce normal haploid gametes and instead produced diploid gametes. As a result, self-fertilization created progeny with 40 chromosomes.
		C.The original F1 hybrid was able to produce normal gametes, thus, the tetraploid was formed by fusing one normal haploid gametes with an abnormal diploid gamete.
		D.Nondisjunction of a random set of chromosomes produced abnormal gametes, and thus the 40 chromosomes represent a random assortment of chromosomes from the two parents.
		E.None of the above can explain the phenomenon.

E.There is no consequence to SOS repair and the damaged DNA is repaired precisely back to the wild-type allele.

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BIOL479 Lecture Notes - Lecture 7: Mutation Rate, Pyrimidine, Purine

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