L100 - Exam two study guide (part 3) – Mitosis, Meiosis & Genetics

1. What is mitosis? Why is mitosis necessary? What is the result of mitosis?

2. What is meiosis?  Why is meiosis necessary?  What is the result of meiosis?

3. What are chromosomes? How many chromosomes do human somatic cells have? Know the relationship between chromosomes,DNA, genes and alleles. What are homologous chromosomes? sister chromatids?

4. Know the terms haploid and diploid. As the gametes are formed during meiosis, understand how and why the cells are going from a diploid to haploid state. When is the diploid state re-established?

5. Know the general process of meiosis. What are the end products of meiosis I? What are the end products of meiosis II? When do the sister chromatids separate? When do the homologous chromosome pairs separate? What are the KEY events in meiosis that we discussed in lecture and lab? Understand the series of events that occurs - you do NOT need to know what happens at each specific stage (prophase, metaphase, etc), just the order of events.

6. Genetic variability in the offspring of sexual reproducing species arises from three major sources: sexual reproduction, the law of independent assortment and crossing over. What is the law of independent assortment? What is crossing over? Understand what is exchanged during "crossing-over." Explain why variation is produced from these events. Tie this into the material you did in lab!!

7. What are autosomes? sex chromosomes? How many pairs of autosomes and sex chromosomes do we have in our somatic cells? gametes? What are the sex chromosomes?

8. Be sure you are comfortable with diagraming out meiosis. You should be able to label sister chromatids, homolgous pairs, show when DNA duplication occurs, show the process of crossing over, when sister chromatids split and when homolgous pairs split.

9. Understand: dominant allele vs. recessive allele; homozygous vs. heterozygous; homozygous recessive vs. homozygous dominant; genotype vs. phenotype.

10. If I were to give you a phenotype, you should be able to predict the genotype (assuming, you are given the information concerning the genetics behind the expression of the trait). If I give you a genotype for a trait, you should be able to give me the phenotype.

11. Understand genetic crosses and predicting the outcome. I can provide you with EITHER the phenotypes or the genotypes of the parents and expect you to be able to come up with the phenotypic and genotypic ratios of the possible offspring. See handouts for some practice questions and answers.

12. Understand: dominant allele vs. recessive allele; homozygous vs. heterozygous; homozygous recessive vs. homozygous dominant; genotype vs. phenotype.

13. Understand the concepts of multiple alleles & co-dominance. Specifically, understand the genetics involved in blood-typing. You should be able to determine the possible blood type(s) of the parents, given the blood type of the child, and the possible blood types of the child, given the blood types of the parents.

14. Understand incomplete dominance, co-dominance and x-linked traits. Again, understand the pattern of inheritance associated with these types of traits.

15. What is polygenic interitance? How does that affect the phenotypes in the popluation? What is the difference between a discontinuous trait and a quantitative trait? Again, provide examples.

16. Understand pedigree analyses. How are recessive traits passed on? Be sure you understand how to do the 'backwards' logic of the pedigree problems. Looking at the phenotype of an offspring, you should be able to predict the genotype of the parent (narrow down the options), and vice versa. Understand the different inhertitance patterns: autosomal recessive, autosomal dominant and x-linked recessive!

17. Explain how genes might interact with the environment. For example, why do Siamese Cats' ears, feet and tails tend to be black and the rest of the body off-white in coloring?

18. What is x-inactivation? Does this happen in males or females? Explain. How does x-inactivation cause the fur coloring (orange and black patches) in Calico Cats?

19. Explain gene linkage? Which of Mendelian laws of genetic does it violate?

20. Understand non-disjunction. You should understand meiosis well enough that you can determine when non-disjunction would have to occur (meiosis I or meiosis II) in order to get a particular combination of chromosomes in a cell.

21. Be comfortable with the three examples we discussed in class of syndromes resulting from an abnormal number of chromosomes: Down's Syndrome, Klinefelter syndrome and Turner's syndrome.

22. Can chromosomal errors be test for in an unborn child? If so how.

MAKE SURE YOU DO THE PRACTICE ROBLEMS posted the web under 'handouts.' Also the material that was presented in lab is NOT irrelevant to the lecture!! Make sure you understand the labs (#7 & #8) .