“In an organism that reproduces asexually, there is no difference between a somatic cell mutation and a germ line mutation.” Is this statement true? Explain.

During the course of a research project you generate a gene knockout line in Arabidopsis thaliana to study the function of a gene you believe plays a crucial role in cellular metabolism.  You note that the initial transformants are a bit smaller than normal.  In subsequent crosses you are unable to isolate homozygotes for the knockout allele.  Heterozygotes in subsequent generation are still a bit smaller than the homozygous wild type plants.   Explain what is happening.

The mutations called bobbed in Drosophila result from variable reductions (deletions) in the number of amplified genes coding for rRNA. Researchers trying to maintain bobbed stocks have often documented their tendency to revert to wild type in successive generations. Propose a mechanism based on meiotic recombination which could account for this reversion phenomenon. Why would wild-type flies become more prevalent in Drosophila cultures?

The beach mouse (Peromyscus polionotus) is a small rodent found in the southeastern United States. Coat color in the beach mouse is variable, from dark brown to blonde (Figure 1). A pigment called eumelanin is responsible for some of the diversity in mouse coat color. The MC1R gene, located on chromosome 8, plays a major role in the synthesis of eumelanin. There are two alleles of MC1R: R allele. Results in a functional MC1R protein that leads to stimulation of pigment production. This allele is found in dark colored mice. C allele. Results in a non-functional MC1R protein. Pigment production is, as a result, not stimulated. This allele is found in light colored mice.   Figure 1. Beach mouse with light fur (left) and dark (right).           These mice are hunted by visual predators like owls and fox. The distribution of coat color is not random. Beach mice with dark fur are found further inland, on dark brown soils while mice with light fur are found on beaches, where the sand is…