2. CHAPTER 11/14

3. I.Mendel A. Gregor Mendel 1. Austrian monk-carried out impt studies of heredity (passing on chars. from parents to offspring) 1. Austrian monk-carried out impt studies of heredity (passing on chars. from parents to offspring) a. traits are inherited 2. Father of Genetics 2. Father of Genetics a. branch of bio that studies heredity

4. 3. Used garden pea due to several good traits/easy to grow a. cross pollination b. true breeding plants (P1-parents) * F1- 1 st gen * F2- 2 nd gen 4. Laws of Heredity a. Law of Segregation b. Law of Independent Assortment

5. II. Crosses A. Genes exist in alternative forms = alleles 1. Dominant allele a. written 1 st b. capital letter (J) c. usually use letter of the dom trait * black hair = B

6. 2. Recessive allele a. lower case (j) letter of dom trait. B. Phenotypes & Genotypes 1. Phenotype = way an org looks (descriptions) a. blue eyes 2. Genotype = allele/gene combi an org has (letters) a. BB

7. b. Heterozygous genotype * Tt c. Homozygous genotype * TT (homoz dom) * tt (homoz rec) C. Punnett Squares 1. Diagram that shows the outcome of genetic combis (checkerboard) a. genes of parents written on the TOP & LEFT side of Punnett 2. Determine geno & pheno of offspring a. Ratios/ percentages/fractions

8. 3. Monohybrid Crosses a. cross between inds involving one pair of contrasting traits (HH x hh) * 4 boxes

9. 4 Dihybrid Crosses a. cross between inds involving 2 pairs of contrasting traits (HhFf x HhFf) * 16 boxes * pheno ratio-9:3:3:1 * geno ratio-4:1:1:1:1:2:2:2:2

11. III. Probability A. In reality you do not get the exact ratio of results shown in the square (chance plays a role) 1. like flipping a coin 2. probability of getting a T vs. a t is 50:50

12. Section 12.2 Summary – pages 315 - 322 IV. Incomplete dominance A. alleles neither dominant nor recessive (use 2 different letters-CAPITAL) 1. 4 boxes B. traits are inherited in an incomplete dominance pattern, the phenotype of heterozygous individuals is intermediate between those of the 2 homozygotes B. traits are inherited in an incomplete dominance pattern, the phenotype of heterozygous individuals is intermediate between those of the 2 homozygotes 1. blending

13. Section 12.2 Summary – pages 315 - 322 C. Example: Homozygous plant (RR) crossed w/ homozygous White-flowered snapdragon plant (WW): Homozygous Red-flowered snapdragon plant (RR) crossed w/ homozygous White-flowered snapdragon plant (WW): ALL of the F 1 offspring will be PINK (RW)

14. Section 12.2 Summary – pages 315 - 322 Incomplete dominance Red White All pink Red (RR) White WW Pink (RW) Pink RW All pink flowers 1/4 red: 2/4 pink: 1/4white

15. Section 12.2 Summary – pages 315 - 322 V. Codominance A. Codominant alleles cause the phenotypes of both homozygotes to be produced in heterozygous individuals. 1. both alleles are expressed equally a. cattle-red hair codominant with white hair = ROAN color

16. Section 12.3 Summary – pages 323 - 329 2. Sickle Cell Disorder=defective hemoglobin forms crystal-like structures that change shape of the RBC’s a. Normal (NN) red blood cells are disc- shaped, but abnormal red blood cells are shaped like a sickle (half-moon). b. homozygote for trait (SS) =sickle cell c. heterozygotes (SN) have both normal & sickle blood cells, but more normal

17. Section 12.3 Summary – pages 323 - 329  change in shape occurs in the body’s narrow capillaries after the hemoglobin delivers oxygen to the cells Sickle-cell disease Normal red blood cell Sickle cell

18. Section 12.2 Summary – pages 315 - 322 VI. Multiple Alleles A. common for more than 2 alleles to control a trait in a population 1. traits controlled by more than 2 alleles have Multiple Alleles

19. Section 12.3 Summary – pages 323 - 329 B. ABO blood group is a classic example of a single gene that has multiple alleles in humans.

20. Section 12.3 Summary – pages 323 - 329 Section 12.3 Summary – pages 323 - 329 Multiple Alleles Govern Blood Type Human Blood Types l A l A or l A i l B l B or l B i lA lBlA lB ii Genotypes Surface Molecules Phenotypes A B A and B None A B AB O

21. Section 12.3 Summary – pages 323 - 329 1. Determining blood type is necessary before a person can receive a blood transfusion because the RBC’s of incompatible blood types could clump together, causing death (immune system will attack).

22. Section 12.3 Summary – pages 323 - 329 2. Gene for blood type, gene l, codes for a molecule that attaches to a membrane protein found on the surface of RBC’s. a. l A & l B alleles each code for a different molecule

23. Section 12.3 Summary – pages 323 - 329 * l A allele is dominant to i, so inheriting either the l A i alleles or l A l A alleles from both parents will give you type A blood. b. Phenotype A Surface molecule A

24. Section 12.3 Summary – pages 323 - 329  l B allele is also dominant to i c. Phenotype B  B blood: must inherit the l B allele from one parent & either another l B allele or the i allele from the other Surface molecule B

25. Section 12.3 Summary – pages 323 - 329  l A and l B alleles are codominant  Universal receiver d. Phenotype AB Surface molecule B Surface molecule A

26. Section 12.3 Summary – pages 323 - 329 e. Phenotype O  Homozygous ii  Universal donor

27. Section 12.2 Summary – pages 315 - 322 A. Humans = 23 pairs 1. 22 pairs of homolog. chrms (autosomes) 2. 23 rd pair differs in males & females (sex chrms) a. XX = girl b. XY = boy 3. X chroms larger a. Barr body VII. Sex Determination

28. Section 12.2 Summary – pages 315 - 322 Sex determination XX Female XY Male X X XY XX Female XY Male XX Female XY Male

29. Section 12.2 Summary – pages 315 - 322 1. Traits controlled by genes located on sex chromosomes = sex-linked traits a. alleles for sex-linked traits are written as superscripts of the X or Y chromosomes a. alleles for sex-linked traits are written as superscripts of the X or Y chromosomes b. many found on the “X” b. many found on the “X” * males just one “X” thus all “X-linked” alleles are expressed even if recessive (from ma) B. Sex-linked inheritance

30. Section 12.2 Summary – pages 315 - 322 Females: Males: 1/2 red eyed 1/2 white eyed all red eyed White-eyed male (X r Y) Red- eyed female (X R X R ) F 1 All red eyed F2F2 Sex-linked inheritance

31. Section 12.3 Summary – pages 323 - 329 c. Females, who are XX, pass one of their X chromosomes to each child. Male Female SpermEggs Female Male FemaleMale Female EggsSperm

32. Section 12.3 Summary – pages 323 - 329 d. sex-linked traits in humans  2 traits that are governed by X-linked recessive inheritance in humans = red-green color blindness & hemophilia

33. Section 12.3 Summary – pages 323 - 329 People who have red- green color blindness can’t differentiate these two colors. Color blindness is caused by the inheritance of a recessive allele at either of two gene sites on the X chromosome. Red-Green Color Blindness

34. b. Determining gamete letters for parents * HhJj (heterozygous for both traits) HJHjhJhj

35. Section 12.3 Summary – pages 323 - 329 A. Metaphase chromosomes are photographed; the chromosome pictures are enlarged & arranged in pairs by a computer according to length & location of centromere. XI. Karyotype

36. Section 12.3 Summary – pages 323 - 329 1.Chart of chromosome pairs =karyotype (it’s valuable in identifying unusual chromosome numbers in cells) a. longest pair #1 b. pairs match (banding, length, traits) c. 23 rd pair = X, Y(smaller chroms) *1-22 pairs = autosomes d. Normal=23 pairs or 46 chrms

37. Section 12.2 Summary – pages 315 - 322 Sex determination  If you are female, your 23 rd pair of chromosomes are homologous, XX.  If you are male, your 23 rd pair of chromosomes XY, look different. X X Female YX Male

38. B. Nondisjunction 1. failure of homologous chroms to separate properly during meiosis- Anaphase a. monosomy 2N - 1 b. trisomy 2N + 1

39. C. Sex Chromo. Anomalies 1. Klinefelter’ Syndrome-XXY (47) 2. Turner’s Syndrome-X?(45) 3. XYY(47) 4. Downs-three 21(47)

40. Section 12.3 Summary – pages 323 - 329 Down syndrome is caused by autosomal trisomy (#21) Trisomy (3’s)

41. Section 12.1 Summary – pages 309 - 314 B. Pedigree is a graphic representation of genetic inheritance. 1. made up of a set of symbols that identify males/females, individuals affected by the trait being studied, & family relationships X. Pedigree A. Family tree that traces family thru successive generations

42. Section 12.1 Summary – pages 309 - 314 Pedigrees illustrate inheritance Male Female Affected male Affected female Mating Parents Siblings Known heterozygotes for recessive allele Death

43. Section 12.1 Summary – pages 309 - 314 2. Circle represents a female; a square represents a male Female Male ? I II III IV 1 2 1 1 1 3 2 2 2 4 3 3 5 4 4 5

44. Section 12.1 Summary – pages 309 - 314 3. Highlighted circles/squares represent individuals showing the trait being studied. ? I II III IV 1 2 1 1 1 3 2 2 2 4 3 3 5 4 4 5

45. Section 12.1 Summary – pages 309 - 314 4. Circles & squares that are not highlighted designate individuals that do not show the trait. ? I II III IV 1 2 1 1 1 3 2 2 2 4 3 3 5 4 4 5

46. Section 12.1 Summary – pages 309 - 314 5. A half-shaded circle or square represents a carrier, a heterozygous individual.

47. 1 2 1 1 1 32 2 2 4 3 3 5 4 4 5 ? I II III IV Section 12.1 Summary – pages 309 - 314 6. Horizontal line connecting a circle & a square indicates that the individuals are parents(marriage), & vertical line connects parents with their offspring.

48. Section 12.1 Summary – pages 309 - 314 7. Ea. horizontal row of circles & squares in a pedigree designates a generation, with the most recent generation shown at the bottom. 1 2 1 1 1 3 2 2 2 4 3 3 5 4 4 5 ? I II III IV

49. 1 2 1 1 1 3 2 2 2 4 3 3 5 4 4 5 ? Section 12.1 Summary – pages 309 - 314 8. The generations are identified in sequence by Roman numerals, & ea. individual is given an Arabic number. a. oldest kid: left I II III IV

50. Section 12.1 Summary – pages 309 - 314 XI. Disorders A. Cystic fibrosis XI. Disorders A. Cystic fibrosis 1. Due to a defective protein in the plasma membrane, cystic fibrosis results in the formation /accumulation of thick mucus in lungs/digestive tract.

51. Section 12.1 Summary – pages 309 - 314 B. Tay-Sachs disease 1. Tay-Sachs disease is a recessive disorder of the CNS. a. recessive allele results in the absence of an enzyme that normally breaks down a lipid produced & stored in issues of the CNS b. lipid fails to break down properly, it accumulates in the cells

52. Section 12.1 Summary – pages 309 - 314 1. Phenylketonuria (PKU), is a recessive disorder that results from the absence of an enzyme that converts 1 aa, phenylalanine, to a different aa-tyrosine. a. phenylalanine cannot be broken down, it & its by-products accumulate in the body & result in severe damage to the CNS C. Phenylketonuria

53. Section 12.1 Summary – pages 309 - 314 b. Infants affected by PKU are given a diet that is low in phenylalanine until their brains are fully developed.

54. Section 12.1 Summary – pages 309 - 314 Phenylketonuria Phenylketonurics: Contains Phenylalanine

55. Section 12.1 Summary – pages 309 - 314 D. Huntington’s disease 1.Huntington’s disease is a lethal genetic disorder caused by a rare dominant allele. a. It results in a breakdown of certain areas of the brain.

56. Section 12.1 Summary – pages 309 - 314 The end