This exercise is designed to familiarize the student with ethology, the study of animal behavior, by observing the behavior of several different arthropods.

The homeobox genes that define the basic body plan of mice and fruit flies are illustrated in this graphic from The Human Evolution Coloring Book by Adrienne Zihlman. The accompanying article describes how these genes act as molecular architects in all animal species.

Unlike most population genetics labs, which involve simulations with beans or beads, this lab provides an opportunity to study a population of living organisms. Using Bar and wild-type Drosophila, students compare allele and genotype frequencies to Hardy-Weinberg expectations. Because the Bar mutation in Drosophila is sex-linked and incompletely dominant, students can determine the exact genotype of a fly from its phenotype. These data are evaluated to determine which (if any) of the five Hardy-Weinberg assumptions have been violated. This real-data approach allows students to appreciate the value of this null model and helps the instructor to discover and correct students' misunderstandings of the model.

Aging involves an intrinsic and progressive decline in function that eventually will affect us all. While everyone is familiar with aging, many basic questions about aging are mysterious. Why are older people more likely to experience diseases like cancer, stroke, and neurodegenerative disorders? What changes happen at the molecular and cellular levels to cause the changes that we associate with old age? Is aging itself a disease, and can we successfully intervene in the aging process?This course is one of many Advanced Undergraduate Seminars offered by the Biology Department at MIT. These seminars are tailored for students with an interest in using primary research literature to discuss and learn about current biological research in a highly interactive setting. Many instructors of the Advanced Undergraduate Seminars are postdoctoral scientists with a strong interest in teaching.

This exercise has been designed to help first-year biology students understand Mendelian inheritance. The pterin (red) eye pigments of wild type and mutant strains are separated using a simple paper chromatography system, and the patterns are analyzed to determine where the metabolic pathway is blocked in each mutant. Crosses of these strains are followed for two generations to provide data that students analyze to determine the mode of inheritance of each mutation, as well as the relationship between each mutant phenotype and the enzyme in the pathway which is affected by the mutation.

Symbiosis is defined as one organism living on, in, or with another organism. Three primary categories are mutualism (both organisms benefit), commensalism (commensal benefits and host not affected), and parasitism (parasite benefits and host harmed). Hands-on dissection of host animals provides examples of live symbiotes in all three types of symbiosis: mutualism: termite flagellates and rumen ciliates; commensalism: Leptomonas flagellates in Drosophila; parasitism: fish hosts (monogeneans on gills, larval digeneans and acanthocephalans in liver) and frogs (trematodes in lungs and bladder; ciliates, flagellates and opalinids in large intestine/cloaca). Possible changes in a relationship from commensalism to parasitism are discussed relative to a demonstration of tapeworm life cycle stages in rat and beetle hosts.

This exercise illustrates to introductory level students that Mendelian patterns of inheritance can be studied using biochemical assays as an indication of biochemical phenotypes. Students investigate the pattern of inheritance of aldehyde oxidase in different strains of Drosophila. Using this information, they study progeny from a mating between unknown parents, develop hypotheses about the parental genotypes, and investigate the results using chi-square test. In addition, students determine the location of the gene by determining the map distance between it and an eye color gene whose location on the same chromosome is already known.

Using Polymerase Chain Reaction (PCR), genetic variation in a laboratory population of Drosophila is characterized. The population contains flies with two variants of a molecular marker. DNA from individual flies is amplified by PCR, generating products which are either "long" or "short" when visualized on an agarose gel. Three PCR "genotypes" (long/long, long/short, and short/short) are distinguishable and should be present in Hardy-Weinberg frequencies. The exercise requires one session for grinding flies and preparing PCR reactions, and one for conducting and interpreting gel electrophoresis. PCR can be conducted with a standard thermal cycler, or using "hand cycling" with two water baths.