Biology 178-001 (Spring 2006): Study Guide for Exam 4

1. How Cells Divide (Chapter 11, P 207-221)

  • Know how prokaryotes divide, including the mechanism of bacterial DNA replication. What is the site of DNA replication called in prokaryotes? What is the FtsZ protein?
  • How are eukaryotic chromosomes organized? What are nucleosomes? Solenoids? What is the composition of chromatin? Why are histones required, and how are they able to wind up the DNA? What is euchromatin? Heterochromatin? How are chromosomes further condensed during mitosis and meiosis?
  • What is a karyotype? What are karyotypes used for? How is a karyotype prepared?
  • What are homologous chromosomes? How do chromosomes duplicate and when? What are centromeres, kinetochores, and sister chromatids? During mitosis how do the microtubules attach to chromosomes?
  • What is ploidy? What are haploid cells? Diploid cells? What is aneuploidy? What are monosomy and trisomy? How many chromosomes do human cells possess?
  • Know why the eukaryotic cell cycle is more complex than the prokaryotic cycle. Know all the stages of the eukaryotic cell cycle and what occurs at each stage. Which is the longest phase of the cell cycle? What determines the length of the cycle in different cells?
  • How would you define mitosis? Know the stages of mitosis (including their order), what occurs at each stage, and the order in which the stages occur (be able to draw and label the stages of mitosis – practice from memory!!!). Also know that mitosis is a continuous process. How does mitosis differ in fungi and some protists from plants and animals? Be able to recognize mitotic and meiotic stages from micrographs.
  • Which organelle reabsorbs the nuclear envelope lipids and proteins? How is a microtubule stabilized during mitosis (and meiosis)?
  • Know what the kinetochore microtubules are. What mechanisms does the cell use to pull the sister chromatids apart? What are cohesins?
  • Know the function and composition of the contractile belt and what a cleavage furrow is. How is the cell cycle different in plant and animal cells (including the mechanisms these cell types use in cytokinesis)? What is the reason for this difference? Be able to diagram cytokinesis in both cell types.
  • Know how the cell cycle is controlled, including the 3 checkpoints, and what occurs when conditions are or are not favorable at each checkpoint. Know what is assessed at each checkpoint (eg. has all the DNA replicated?). Why is it important for cells to control their division rate?
  • What are the mechanisms of cell cycle control at the molecular level?
  • What is the name of the type of enzyme that adds phosphates to molecules? Removes phosphates? What are cyclins and cdks and how do they function? Which cell cycle molecule is synthesized and degraded at specific points in the cell cycle? How are cdks activated (2 mechanisms)? Inactivated?

2. Sexual Reproduction and Meiosis (Chapter 12)

  • What is the biological purpose of sex?
  • In sexual reproduction, what 2 methods maintain chromosome number from generation to generation?
  • Know what gametes and fertilization are and to what the term “alternation of generations” refers.
  • Understand that there are 3 types of sexual life cycle, which differ with respect to how gametes are produced, and which is the dominant stage (diploid or haploid). What are the names of these 3 cycles? How were their names derived? What is a zygote? How is it produced? Know the animal life cycle (be able to draw and label).
  • Know what maternal and paternal chromosomes are, how crossing over occurs, between what and when in meiosis it occurs. Also know the function of crossing over, and what synapsis is. During synapsis, where in the cell would you find the homologues? What is the synaptonemal complex? What is the function of a recombination nodule? What is the composition of a recombination nodule? Be able to answer questions on micrographs of synaptonemal complexes (examine the website you were given in class!) What are chiasmata? What happens to the synaptonemal complex after completion of crossing over? How are the homologues now joined and where are they in the cell? What would be the consequence of no crossing over in meiosis?
  • Know the stages of meiosis, what occurs at each stage, and the order in which the stages occur (be able to draw and label!). What are the 3 principle events (remember the video!) that distinguish meiosis from mitosis? How many times in meiosis is the DNA duplicated? What is the ploidy of the daughter cells? Which event is lacking in meiosis that results in this ploidy? What happens to the chiasmata in prophase I? Why in metaphase I do the microtubules only attach to the outward facing kinetochores? What is the significance of this? Be able to define independent assortment. Know the equation (and be able to use) that determines how many possible gametes can occur as a consequence of independent assortment alone. What does n represent? What are the sources of genetic variation in meiosis?
  • Know the differences between mitosis and meiosis. Finally, know the evolutionary consequences of sex.

3. Gametogenesis (Chapter 50, P 1068-1074)

  • What is gametogenesis?
  • What is spermatogenesis? How many daughter cells are produced by this process? Where in the body does it occur? Be able to describe the structures and functions of the seminiferous tubules and the epididymis. What happens to the cells as they move from the outside of the tubule to the lumen?
  • What are spermatogonia? What is their ploidy? Their function? What are primary and secondary spermatocytes? What are spermatids? What is their ploidy? How do they change as they mature? By which process are all these cells produced, mitosis or meiosis? What is the function of a sertoli cell?
  • Be able to describe the structure (and label diagrams) of sperm. What is the acrosome? What is its function? Where would you find the mitochondria?
  • What is oogenesis? How many daughter cells are produced by this process? Where in the body does it occur? In what stage of meiosis are the oocytes of a newborn baby girl? What are primordial follicles?
  • What is the function of FSH? What are polar bodies? What is their function? In what stage of meiosis are secondary oocytes? What is the structure of a follicle?
  • What is ovulation? What is the corpus luteum? What is its function? What process will result in an oocyte completing meiosis II? Where in the body would this occur? If an ovum is fertilized how is the corpus luteum maintained? What happens to the cycle if the corpus luteum degenerates?

4. Patterns of Inheritance (Chapter 13, P 241- 256, 259-262, 265-266, & 270-274)

  • What ideas were prevalent about heredity in the scientific community prior to Mendel’s time? Be familiar with the works of Koelreuter and Knight and how these differed fundamentally from the work of Mendel.
  • Know why the work of Mendel is so important, how he designed his experiments, and why he chose the garden pea as his study subject. Know what the P, F1, and F2 generations are. What were Mendel’s conclusions from his experiments?
  • Be able to define genes, homologous chromosomes, heterozygotes, homozygotes, alleles, loci, genotype, and phenotype. Know what dominant and recessive traits are and how they are represented in genetics problems.
  • Know how to perform monohybrid and dihybrid genetic crosses (you will be asked to work through problems).
  • Know what a testcross is and why it is performed. What results would you predict from a testcross?
  • Know Mendel’s 2 laws and be able to define them in terms of meiosis.
  • How would mendelian traits be defined? Non-mendelian traits? Be able to work through problems on both mendelian and non-mendelian patterns of inheritance.
  • Be able to work with problems involving multiple alleles and know what codominance is, particularly the example of the ABO bloodtype. Why do different individuals have different ABO blood types? Which type is the universal donor? Universal recipient? Know also what the Rhesus blood group antigen is, the danger it can pose during pregnancy (including what erythroblastosis fetalis is), how such problems can be resolved, and be able to work through problems on both the Rhesus factor and ABO blood groups. Why is Rhesus a problem in pregnancy, but ABO is not? How does one develop antibodies to Rhesus? ABO?
  • Know what quantitative traits (polygenic inheritance are (including being able to identify graphs of this type of inheritance) and be able to give examples.
  • What is pleiotropy? Be able to give examples and work through problems involving this type of inheritance. What are lethal alleles? How would you recognize a situation involving lethal alleles?
  • Know what incomplete dominance is, how it differs from codominance, and how it alters the typical Mendelian phenotypic ratio. Be able to work with problems on both incomplete dominance and codominance.
  • Know how the environment can affect the expression of some alleles and be able to give an example. Be able to work with problems on this type of inheritance.
  • Know that genetic diseases can be inherited both recessively and dominantly. What is hemophilia? Know what sex-linked hemophilia is and how it is inherited. What is the genotype of a carrier? Sufferer? How did this disease impact history?
  • Know what causes sickle-cell anemia, its effects, and how it is inherited. Also know why this disease is common in blacks (why heterozygotes have a selective advantage). What is Plasmodium falciparum? Where in the body would you find it?
  • Know what Huntington’s disease is, how it is inherited, and why the deleterious allele continues to persist. Why do nerves degenerate in this disease? What is the cure for this disease?
  • Who (and in what year) was responsible for the Chromosomal Theory of Inheritance? What evidence was this based on? What was the response of the scientific community and what was their reasoning? Who was responsible for the evidence that finally convinced the scientific community? Why was this evidence so convincing?
  • Be familiar with Morgan’s Drosophila eye color experiment. What year was this discovery made? How did this demonstrate sex linkage? Be able to work through problems involving this data.
  • Know what autosomes and sex chromosomes are and how the sex of a human is determined. How is the sex of other organisms determined? What is a Barr body? What is the reason for the occurrence of a Barr body in cells? Which X chromosome is inactivated? Where in the cell would you find a Barr body?
  • Be able to solve problems on sex linkage.
  • Know what nondisjunction, aneuploidy, monosomy, and trisomy are. Be able to give an example of nondisjunction of autosomes. Why do older mothers have a greater tendency to produce children with aneuploidy than younger mothers? Know the examples of nondisjunction of sex chromosomes (triple X syndrome, Klinefelter syndrome, Turner syndrome, OY, and XYY males) and how they arise. What are the phenotypes of these individuals? What is the significance of the Klinefelter calico cat?
  • Be able to solve problems involving pedigrees, including being able to draw your own.
  • Know what genetic counseling is and what methods genetic counselors use.

FOR THIS EXAM, USE YOUR QUIZZES, THE QUESTIONS FROM P 276-278, AND THE PRACTICE EXAM TO STUDY. MAKE SURE YOU HAVE DONE THE PRACTICE EXAM PRIOR TO COMING TO THE REVIEW SESSION (BRING YOUR ANSWERS WITH YOU), WHICH WILL BE ON TUESDAY, APRIL 11th AT 2 PM IN SCIENCE 106. YOU WILL NEED TO BE ABLE TO DRAW ALL THE STAGES OF MITOSIS AND MEIOSIS FOR THIS EXAM (PRACTICE, PRACTICE, PRACTICE FROM MEMORY!). ALSO, YOU WILL HAVE TO BE ABLE TO SOLVE GENETICS PROBLEMS– THE MORE PRACTICE (ie. THE MORE PROBLEMS YOU HAVE ATTEMPTED), THE MORE COMPETENT YOU WILL BE - KEEP WORKING AT IT!!!