BIOL 120 - Study Guide - Test #4

Exam is scheduled for Monday, December 5th
Includes information from Chapters 8, 9, 13, 14, and 15

The exam with be entirely multiple choice, true/false, and matching. BRING A #2 PENCIL, ERASER, AND A NARROW SCANTRON SHEET. The following is a general outline of what I consider to be some of the more important points that we have covered so far. Test material will include everything covered through the end of Friday’s (Dec. 2^nd) lecture.

CHAPTERS 8 & 9: Human Genetics (8: 10, 11; 9: 14, 15)

· Humans and many other eukaryotes have two “kinds” of chromosomes: Autosomes (normal, everyday chromosomes); Sex chromosomes (those involved with determining sex)

· In humans, it is the Y (or genes on the Y, specifically the SRYgene) that determines sex, the X has nothing to do with sex, but instead has normal, everyday genes

· Sex Linkage: Genes located on the sex chromosomes are inherited in a criss-cross fashion. Y-linked genes are never expressed in females. X-linked recessive traits tend to be expressed more often in males than females. Males are said to be hemizygous for X-linked genes

· X-chromosome Inactivation: in female mammals, one X chromosome in each cell is inactivated (called dosage compensation). This X inactivation accounts for some differences between different tissues in some female mammals (i.e. calico coat color in cats). Allows for both male and female cells to be the same with respect to X-linked genes

· Human Disorders Caused by Changed in Chromosome Number

· Nondisjunction = failure of chromosomes (or chromatids) to disjoin during meiosis. 1/2 of the gametes will have an extra chromosome, and 1/2 of the gametes will be missing a chromosome. Results in aneuploidy.

· Human Aneuploidy: Sex chromosome nondisjunction - know the following- Klinefelter syndrome, triplo-X, Turner syndrome, XXY.

· Autosomal nondisjunction – know the following - Down syndrome, Edward syndrome, Patau syndrome.

· Alterations of Chromosome Structure – Deletions, Duplications, Translocation, Inversion

· Detection of chromosomal or genetic disorders: Amniocentesis, Chorionic villus sampling.

CHAPTERS 13 & 14: Classification, Speciation & Evolution (13:4; 14:1, 4, 5, 6, 7, 9, 12)

• All life on earth classified via taxonomy and named by binomial system of nomenclature.
• Each species given specific name - recognized by combination of Genus species.  Related genera grouped into Families, families into Orders, orders into Classes, classes into Phyla, and phyla into Kingdoms.  Only species are REAL - based on reproductive isolation (prezygotic & postzygotic – understand the basic kinds of pre- and postzygotic reproductive isolation).
• Systematics  deals with organizing groups of taxa together into a phylogeny, which attempts to group all organisms into monophyletic groups, or groups of individuals who all originated from a common ancestor.  Done by comparing homologous structures and grouping together individuals with the same derived character states = synapomorphic characters  (i.e. all mammals have hair, no other organisms do).
• Cladistics - used to create cladograms to organize life into taxonomic hierarchy.
• natural selection - how does it work?  What is decent with modification?
• evolution - definition?!? Evidence of evolution? causes?
• What are the three basic types of selection? Sexual selection?
• What is the biological species concept?
• Speciation by allopatric or sympatric models.  Have led to diversity of life.  Biological species concept highlights inportance of reproductive isolation.
• anagenesis vs. cladogenesis
• 4 basic steps involved in our hypothesis of the origin of life – what are they?
• How does the Miller-Urey experiment relate to these events?
• Know timing of major events in the history of life.
• Origin or eukaryotes – what is serial endosymbiosis? How did this lead to the formation of mitochondria & chloroplasts?

Chapter 15 – Geologic History & Macroevolution (15:3, 4, 5, 6, 10)

• Much of what we know about the history of life on earth is from the fossil record. The changes noted by following the fossil record are generally macroevolutionary changes. Changes in fossils used to generate the geologic record. The history of Earth has been divided into three eons: know these! The most recent eon is further divided into three Eras: know these and the major events that occurred during each.
• Mechanisms of Macroevolution: Continental Drift. Based on available evidence, all of the land masses on earth have come together to form a supercontinent at least 3 times, the most recent was ~250 mya. Pangea is the name given to this single continent - plate tectonics (movement) have slowly been moving landmasses to their present positions. The formation of Pangea – and it’s breakup – led to many important changes in animals and plants. Pangea split ~180 mya into Laurasia and Gondwana resulting in massive allopatric speciation; India collided with Asia ~55 mya forming the Himalyayan mountains; Isolated areas such as Australia developed vastly different life forms than other areas that were still connected.
• Mechanisms of Macroevolution: Mass Extinctions. At least 5 major mass extinctions are recorded in the fossil record, the most recent resulted in the extinction of the dinosaurs. Evidence suggests that a massive climate change resulted from a large asteroid impact near the Yucatan peninsula of Mexico. Following each mass extinction, adaptive radiations occur.
• Mechanisms of Macroevolution: Adaptive Radiation. Single types of organisms “radiating” into many kinds usually associated with some type of “release”: Competitive pressures removed; new resources become available, new adaptations allow organisms to take advantage of previously unavailable resources.