Lecture, chapter 11 - Mutation

Today we started the chapter on mutation.

We focused on mutations at the nucleotide sequence level since in previous chapters we have discussed mutations at the chromosome level. We talked about the most common agents that cause mutation (mutagens), such as chemical agents and ionizing radiation.

We discussed why certain mutagens can cause specific kinds of mutations mutations and what some of the possible effects in the phenotype could be. Radiation captured our attention for much of the lecture.

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Lab 06 - Gene mapping in Drosophila

Wednesday, January 20, 2010

Today we did lab 06, on mapping genes in Drosophila.

We discussed concepts like linkage, recombination, crossing over, and as a consequence the existence deviations from Mendelian principles, specially from independent assortment. We mentioned how genes that are in the same chromosome may also be unlinked, if the distance between them (measured in centimorgans (cM) is big enough.

Using DrosophiLab, a crossing-over simulator (from Paul Lewis' lab), and paper and pencil, students learned how to

• Determine the distance between two genes in the same chromosome (measured in cM or map units (M.U.))
• The effect of the distance between genes and the size of a chromosome in the frequency of recombinant chromosomes during meiosis
• How to map genes based on gene distances
• How to map genes and find the distances between them based on phenotypic data (resulting from simulated crosses)

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Lecture, chapter 10 - From proteins to phenotypes

Today we covered chapter 10, on how proteins can affect the phenotype of an individual, specially in humans.

We discussed effects that mutations could have in the phenotype when they alter enzymes, transport proteins, and receptor proteins. Then we discussed the effects of genotypes on how an individual reacts to chemicals, which is the scope of pharmacogenetics, and how an individual reacts to chemicals in the environment, the scope of ecogenetics.

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