Galactic dynamics: potential theory, orbits, collisionless Boltzmann equation, etc. Galaxy interactions. Groups and clusters; dark matter. Intergalactic medium; x-ray clusters. Active galactic nuclei: unified models, black hole accretion, radio and optical jets, etc. Homogeneity and isotropy, redshift, galaxy distance ladder. Newtonian cosmology. Roberston-Walker models and cosmography. Early universe, primordial nucleosynthesis, recombination. Cosmic microwave background radiation. Large-scale structure, galaxy formation.

Biology 2e is designed to cover the scope and sequence requirements of a typical two-semester biology course for science majors. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology includes rich features that engage students in scientific inquiry, highlight careers in the biological sciences, and offer everyday applications. The book also includes various types of practice and homework questions that help students understand—and apply—key concepts. The 2nd edition has been revised to incorporate clearer, more current, and more dynamic explanations, while maintaining the same organization as the first edition. Art and illustrations have been substantially improved, and the textbook features additional assessments and related resources.

By the end of this section, you will be able to do the following:

Explain Mendel’s law of segregation and independent assortment in terms of genetics and the events of meiosis
Use the forked-line method and the probability rules to calculate the probability of genotypes and phenotypes from multiple gene crosses
Explain the effect of linkage and recombination on gamete genotypes
Explain the phenotypic outcomes of epistatic effects between genes

By the end of this section, you will be able to do the following:

Discuss Sutton’s Chromosomal Theory of Inheritance
Describe genetic linkage
Explain the process of homologous recombination, or crossing over
Describe chromosome creation
Calculate the distances between three genes on a chromosome using a three-point test cross

Enzymes, nature's catalysts, are remarkable biomolecules capable of extraordinary specificity and selectivity. Directed evolution has been used to produce enzymes with many unique properties, including altered substrate specificity, thermal stability, organic solvent resistance, and enantioselectivity--selectivity of one stereoisomer over another. The technique of directed evolution comprises two essential steps: mutagenesis of the gene encoding the enzyme to produce a library of variants, and selection of a particular variant based on its desirable catalytic properties. In this course we will examine what kinds of enzymes are worth evolving and the strategies used for library generation and enzyme selection. We will focus on those enzymes that are used in the synthesis of drugs and in biotechnological applications. 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.

When two different strains of influenza infect a single cell, their genetic material can mix freely, resulting in a new third strain of influenza.