Genetics – the study of heredity

1. Genetics – the study of heredity Based on the study of probability (likelihood)

2. 1. Why should we study genetics? • Disease causes/treatments • Biotechnology – agriculture, animal husbandry • Breeding • Pedigrees- family lineages • Evolutionary trends

3. 1.How are genes passed on to our offspring? 2. Sperm carry ½ and eggs ½ of genetic code.

4. 1. How are sperm & eggs produced? 2. Meiosis – germ cells divide to produce haploid cells (1 set of chromosomes) 3. Haploid =1N

5. 2. Meiosis has 2 divisions to reduce chromosome number

6. 2. What are the phases of meiosis? • Meiosis I • Prophase I- Crossing over of alleles occurs! • Metaphase I- homologous chromosomes side by side • Anaphase I- ho. chrom. separate (not chromatids) • Telophase I- 2 cells with 2 chromatids of every chromos.

7. Meiosis II • Prophase II- nothing happens • Metaphase II- chromo align single file • Anaphase II- chromatids pull apart • Telophase II- 4 total cells w/ 1 copy of each chromo.

10. 1N + 1N = 2N (a diploid cell) 46 XX= female 46 XY = male 23 pr homologous chromosomes

11. What are the results of meiosis? • 4 cells • Genetically different • Haploid (1N) • In females, only one egg is used

13. What happens if chromosomes don’t separate properly?

14. Nondisjuction results in trisomy or monosomy

15. Dragon genetics activity to learn basic vocabulary Check for understanding following activity: BB Bb Bb Allele/gene Genotype/phenotype

16. Mate your dragons

17. Punnett squares • Designed to PREDICT outcomes (expected ratios)

18. Single gene crosses • monohybrid: Aa x Aa • Or : AA x Aa • Or Testcross: aa x A_____

19. Cystic fibrosis • Due to a recessive allele (ff) • Faulty membrane protein does not regulate NaCl • Cells create mucous around them/breeding ground for bacteria • Chromo #7

20. Huntington disease • Due to a dominant allele • Late onset (35 years+) • Protein (huntingtin) destroys nerve cells • Due to a repeat of more than 21 CAG in a gene • Chromosome 4 (discovered in 1983) • Maracaibo, Venezuela- Huntington research

22. Di- crosses probability problems • Rh factors- effect on fetus- protein on RBC- rh from RHESUS monkey- Rh neg makes antibodies against Rh protein- • Rh is important during fetal development • Albinism- due to recessive alleles

23. Review terms • Alleles/gene • Genotype/phenotype • Homozygous/heterozygous • Probability • Offspring/ F1/F2 generations • Dominant/recessive

24. Quiz • 1. Explain how an allele is related to a gene. • 2. What is the relationship between a genotype and a phenotype? • 3. Which of the following combinations are homozygous? BB Bb bb

25. 4.  T-tall t – short Y –yellow y- green • Cross a plant that is heterozygous tall and homozygous for green seeds with a plant that is short and is also homozygous for green seeds. •  List the genotypes and ratios for the above cross. • List the phenotypes and ratios for the above cross.

26. Codominance • Both alleles of a gene express themselves= both proteins are produced • Examples: • AB blood type (protein “A” and protein “B”) • Sickle cell trait ( point mutation in hemoglobin)- produces 3 phenotypes- normal, trait, anemia

27. Blood type importance Your immune system makes antibodies against foreign proteins. Antibody A attacks blood type A Antibody B attacks blood type B Antibodies A & B attack blood type AB Antibodies A & B DO NOT attack blood type O

28. blood types- multiple alleles Phenotype (protein) Genotype (alleles) AA or AO BB or BO AB OO • Blood type A • Blood type B • Blood type AB • Blood type O

29. Blood type lab • Antibodies can cause blood to clump (agglutinate) • This is how blood is “typed” for accuracy for transfusions.

30. What is the importance of sickle cell trait? • Evolutionary advantage to survive Malaria • “heterozygote” advantage- NS (trait) • “S” cells sickle and the protozoan is killed

31. Video clip on sickle cell evolution http://www.pbs.org/wgbh/evolution/library/01/2/l_012_02.html

32. Normal RBCs vs. Sickle RBCs phenotype genotype NN NS SS • Normal blood cells • ½ normal & ½ can sickle • all can sickle

33. Incomplete dominance • 2 alleles “blend” their traits and produce a 3rd phenotype • Examples: • Palamino horses (ncomplete & polygenic) • Tay-Sachs enzyme levels (enzymes, some enzymes, no enzyme)

34. Some flowers

35. X linked genes • Genes that are located on the X chromosome only • Examples • Hemophilia • Red-green color blindness • Duschene muscular dystrophy • Calico cats • ALD (Lorenzo’s oil disease)

36. hemophilia • Hemophiliacs lack protein factors for clotting.

38. Pedigrees

39. Red – green color blindness

41. Muscular dystrophy

42. Image of Calico cat- x linked & epistatic genes

43. Epistatic genes • Genes that “cancel” out other genes

44. Pedigrees • Family trees that show inheritance

45. Environmental effects on genes

46. Polygenic inheritance • More than one gene codes for a trait Examples” skin color, eye color, height, hair color Genes are “additive”

47. Chromosomal changes

48. Turner’s Syndrome Occurs in females. Missing an entire X chromosome. Non-working ovaries (no menstrual cycle) Short stature and webbed neck Increased risk of heart and cardiovascular problems

49. Triple X Syndrome • Three X chromosomes • Only one X chromosome is active at a time (little adverse effects) • Tall stature, small head, fold in skin • Learning disabilities. Low self esteem • Fertile

50. Poly X Syndrome • XXXX and XXXXX • Similar symptoms to XXX • Small head and jaw • Very tall stature • Irregular shaped heart and lungs • Very low IQ 10-15