Reference no: EM132849799

Lecture title: Mendelian Genetics, Part I

1. GUIDING QUESTION: The history of the study of inheritance is a peculiar one, but also one that reveals that the march of scientific progress is not always a consistent driving forward but often occurs in spurts. Significant time was lost in the study of genetics during the late 19th Century. Charles Darwin published his ideas about evolution and natural selection but utterly failed to understand the mechanism of inheritance. Meanwhile, Gregor Mendel (a contemporary of Darwin) deciphered the basics of genetic inheritance; however, the scientific establishment at the time overlooked Mendel's insights and only re-discovered his work in the early 20th Century, long after Mendel had passed. For approximately 40 years, biologists failed to merge Mendel's genetic work with Darwin's evolutionary work. That is a lot of lost time. Reflect on this issue. What human factor(s) do you think likely contributed to such a lag in scientific progress? Name at least one change in practice that scientists could adopt that might prevent (or at least minimize) such lags going forward in the 21st Century.

2. Who is Gregor Mendel? During what time period did he live? What kinds of questions did he seek to answer?

3. Define the following terms: gene, allele, complete dominance, dominant allele, recessive allele, genotype, phenotype, homozygous, heterozygous, Punnett square, monohybrid cross,dihybrid cross, and locus.

4. List at least seven monogenic traits in humans (as discussed in class lecture).

5. Erasmus Darwin had (not well-formulated) ideas of evolution. Who is Erasmus Darwin?

6. Who is Jean-Baptiste Lamarck? Explain "Lamarckism" in terms of inheritance. Is Lamarckism biologically correct?

7. What is a homunculus and the "preformation hypothesis?"

8. What type of plant species is Mendel widely known for using in his landmark genetics experiments? Name at least five traits that he studied in this model system.

9. Briefly summarize the reproductive life cycle of pea plants and how Mendel performed manipulative breeding experiments in this model system.

10. How did Mendel produce "pure-bred" pea plants that bore yellow seeds or green seeds only? (HINT: We would now call these plants homozygous for the yellow allele or the green allele.) What were the results of Mendel's initial cross of homozygous (pure-bred) yellow and homozygous (pure-bred) green pea plants? Why was this surprising at the time (mid-19th Century)?

11. What is the classic ratio of pea color phenotypes (that Mendel observed) for a monohybrid cross in the case of one gene, two alleles, and complete dominance?

12. What is the classic ratio of pea color and texture phenotypes (that Mendel observed) for a dihybrid cross in the case of one gene, two alleles, and complete dominance?

13. Name and describe the two laws known as Mendel's laws. In what phases of meiosis are these two laws now known to apply?

Lecture title: Mendelian Genetics, Part II

14. GUIDING QUESTION: For much of the 20th Century, the so-called nature/nurture debate raged among scientists and other scholars. It is now well understood that most of the human traits of interest in this debate are determined by BOTH "nature" and "nurture." More specifically, this means that many human traits of interest (such as alcoholism, personality, intelligence) are influenced by a combination of, or interaction between, genetics and environment. Let's have a closer look at alcoholism. Provide at least one argument for the genetic basis of this human condition and at least one argument for the environmentally determined aspect of this condition. (You will need to do some research; do your best to use only reliable resources!)

15. By chance, _______________ chose a model organism (pea plants) and study traits that: (1) ______________________, and (2) ________________________.

16. The topic of "sex-linked traits" will be discussed in the upcoming lectures on "chromosomal biology." Other than "sex-linked traits," what other five topics involving increasingly complex genetics were addressed during this lecture?

17. Define incomplete dominance, and discuss the two examples addressed in lecture involving flower color in snapdragons and coat color in some horses.

18. Define co-dominance, and what is meant by "genes with multiple alleles." How does the ABO blood typing system exemplify co-dominance? Which alleles are co-dominant? Which allele is recessive?

19. What is an antigen? What is an antibody? For each of the four primary blood types in humans (A, B, AB, and O), list the red blood cell surface antigens and immune system antibodies associated with each blood type? How is this information fundamentally important in preventing blood transfusion reactions?

20. What is "the Rh factor?" Do the Rh +/- alleles conform to co-dominance, incomplete dominance, or complete dominance? What is hemolytic disease, and what are the preconditions in which hemolytic disease may occur during pregnancy?

21. What is meant by the term "polygenic inheritance?" Name three human traits that are polygenically inherited.

22. Can a Punnett square be used (theoretically) to predict offspring phenotypes for (at least some) polygenic traits, such as skin color? Is it practical to use Punnett squares for this purpose?

23. Define pleiotropy, and discuss the two examples addressed in lecture involving the so-called Frizzle mutant allele in chickens and the sickle-cell anemia mutant allele in humans. How is the mutant sickle-cell anemia allele emblematic of the potential role of heterozygotes and pleiotropy in enhancing human genetic variation?

24. Define epistasis, and discuss the two examples addressed in lecture involving coat color in mice (and other mammals) and fruit color in some plants.

25. Although genes often play a role in determining biological traits, the role of _______________ is also very important.

26. Give an example of a relatively (1) small, (2) medium, and (3) large environmental effect on phenotype.

27. What is polyphenism, and how are ant castes emblematic of polyphenism?

28. What is an inducible defense, and how are microscopic Daphnia freshwater zooplankton emblematic of inducible defense?

29. What is the role of environmental temperature in sex determination of certain reptiles, such as turtles?

30. Explain how the coat color of Siamese cats demonstrates the role of environment in phenotype determination.

31. What is the current understanding of the so-called "Nature vs. Nurture" debate with respect to traits of wide interest in humans?

Lecture title: Chromosomal Biology, Part

32. GUIDING QUESTION: There are several non-lethal human abnormalities that are caused by departures from the normal number of sex chromosomes (XX in females, XY in males). In class, we discussed one of these conditions, Klinefelter's Syndrome, in which individuals possess two X chromosomes as well as one Y chromosome (XXY). Most individuals with this condition are characterized by at least a few of the following characteristics: female-type pubic hair pattern, small testes, breast development, poor beard growth, and osteoporosis among other items. Other human conditions caused by sex chromosomal abnormalities include Turner Syndrome and Trisomy X. For each of these two conditions, point out the nature of the sex chromosomal abnormality (that is, how many X and/or Y chromosomes). Then, provide at least three characteristics that individuals with each of these two conditions commonly possess.

33. Chromosomes are composed of ___________ and ____________. Chromosomes reside in what important cellular organelle (in eukaryotes)?

34. The DNA in a chromosome codes for _____________ of genes, and each gene is made up of ___________ of nucleotides.Each gene directs the production of a single______________. How many genes do humans have?

35. What is a karyotype, and how is it important in diagnosing certain genetic disorders?

36. What is the central tenet of the chromosome theory of inheritance?

37. List and discuss the biological consequences of each of the four major types of chromosomal rearrangements.

38. REVIEW the following terms: homologous pairs (of chromosomes), genetic locus (plural = loci), allele, dominant, recessive, homozygous, and heterozygous.

39. What is an autosome? What is a sex chromosome? On which chromosome is the SRY gene located, and what is this important gene's primary function?

40. List three (of the five) ways in which new combinations of alleles arise that directly involve chromosomes. Which two of these three ways is directly related to Mendel's Laws?

41. What is meant by the term "genetic linkage?" What impact does crossing over have on genetic linkage?

42. Explain why (in the left figure below) why only two gamete types are represented for the heterozygote individual in the F1 generation. Then explain why (in the right figure below) two additional genotypes/phenotypes are observed in actual crosses in the lab despite the Mendelian prediction of only two genotypes/phenotypes (corresponding to "ggww" black-bodied flies with reduced wings and "GgWw" gray-bodies flies with normal wings).

43. Discuss the benefits of studying genetic disorders in humans. Provide three reasons why doing so is difficult in humans.

44. Two human disorders that are attributable to a mutant allele at a single locus are sickle-cell anemia and cystic fibrosis. For each of these genetic disorders, what areas of the world are predominantly affected? In at least one case (sickle-cell anemia), there is a well-documented benefit to human bearers of the mutant allele; what is this benefit?

45. What is meant by "trisomy 21," and what human disorder does it cause? What is a chromosomal non-disjunction? In what stage(s) of meiosis might a non-disjunction occur?

46. What is Klinefelter's Syndrome? Is it caused by a chromosomal non-disjunction? Which human sex is affected by this condition?

Lecture title: Chromosomal Biology

47. GUIDING QUESTION: Some clinical geneticists provide genetic counseling to couples wishing to build a family. Pedigree analysis can be used to determine the likelihood that the couple's offspring would inherit a genetic condition, such as sickle-cell anemia, cystic fibrosis, and Huntington's disease, to name a few. One common misconception about pedigrees is that the presence of many affected individuals in a family does NOT always mean that the trait is dominant. How is this possible? Why might recessive disorders be maintained within families and in the general population as well?

48. Differentiate between autosomes and sex chromosomes.

49. What is a genetic carrier? Are carriers associated with autosomal dominant or recessive traits?

50. List the following major features of autosomal recessive genetic conditions/disorders: homozygotes/heterozygotes, the possibility of carriers, the possibility of generation-skipping, the commonness or rarity in human populations.

51. List the following major features of autosomal dominant genetic conditions/disorders: homozygotes/heterozygotes, the possibility of carriers, the possibility of generation-skipping, the commonness or rarity in human populations.

52. What kind of inheritance is exhibited by Huntington's disease? Cystic fibrosis? Sickle-cell anemia? Achondroplasia ("dwarfism")?

53. Be sure that you can answer common questions (e.g., is this pedigree possible given a certain pattern of inheritance?) using standard pedigrees for (a) autosomal dominant and (b) autosomal recessive genetic conditions/disorders.

54. Can males be heterozygous for X-linked genes? Why or why not?

55. Are males more or less likely to inherit X-linked recessive disorders? Why? What about females?

56. Are X-linked recessive disorders relatively common or rare?

57. Are males more or less likely to inherit X-linked dominantdisorders? Why? What about females?

58. Are X-linked dominant disorders relatively common or rare?

Attachment:- Mendelian Genetics.rar