Lecture, chapter 8 - Nucleic acids

Today we covered most of chapter 8, on DNA structure and chromosomal organization.

We reviewed a brief time line of discoveries that lead us to know what we now know about nucleic acids, from the discovery of nuclein to the structure of DNA, for which Crick, Watson, and Wilkins received the Nobel prize in 1962. We remembered the important role that Rosalind Franklin played on the discovery of the DNA double helix, and how Watson neglected to acknowledge her properly (as well as the committee in charge of awarding the Nobel prize).

We compared the basic differences between DNA and RNA, introduced important concepts to comprehend nucleic acid lingo, and discussed the basics of the mechanisms in place for a cell to supercoil DNA into densely packed chromosomes visible during metafase in cell division.

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Lecture, chapter 6 - Cytogenetics

Today we started the chapter on cytogenetics.

We discussed chromosome terminology, the steps to prepare a human karyotype, and generalities about chromosome abnormalities: Polyploidy, aneuploidy, and the most common cases and causes of each.

We then discussed structural alterations (duplications, deletions, inversions, and translocations (reciprocal and Robertsonian), and other abnormalities (Double Uniparental Disomy and fragile sites).

The details of each case of aneuploidy were covered by students as an independent reading and will be tested.

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Lab 05 - Heritability (of quantitative traits)Lab quiz 1

Today we did our lab in heritability, a calculation that can be done when dealing with quantitative traits.

Heritability: The proportion of phenotypic variation explained by genotypic variation (as opposed to environmental factors).

Broad sense heritability (H^2): Heritability taking into account all kinds of genetic interactions (additive effects of polygenes, epistasis, dominance-recessiveness, etc.)

We used finger print ridge count data to calculate the broad sense heritability of the trait. in our "population" (the class). Every student took his/her own fingerprints and did a ridge count on each one. We pooled everybody's data and proceeded with the calculation.

Narrow sense heritability (h^2)*: Heritability taking into account only the additive effects of polygenes. This measure is of interest to individuals who are interested in selection programs with the goal of shaping a population according to their interests (e.g. farmers or cattle breeders).

We used height data from students, their parents, aunts and uncles, and siblings, to calculate h^2 in a human population, since we had the data available. This kind of heritability is usually not calculated in humans.

*Actually performed a week later, on April 13.

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Lab quiz 1

During the last hour of today's lab students took the first lab quiz.

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