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Genetics

Genetics. Genetics A. Gregor Mendel 1. 1 st study on heredity a. passing of characteristics from parents to offspring. 2. Occupation: monk 3. Worked with pea plants a. self-pollinators meaning inherit all characteristics from the original plant or identical: true-breeding.

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Genetics

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  1. Genetics

  2. Genetics • A. Gregor Mendel • 1. 1st study on heredity • a. passing of characteristics from parents to offspring.

  3. 2. Occupation: monk 3. Worked with pea plants a. self-pollinators meaning inherit all characteristics from the original plant or identical: true-breeding.

  4. b. Produce sexually sperm & egg: gametes 1) sperm: pollen; egg: ovule 4. Cross pollination – pollen from one plant fertilizes egg from another

  5. a. hybrid: offspring have different characteristics from parents

  6. 5. Trait: specific characteristic a. studied 7 traits – p. 262, Green 179) b. original plant: P (parental) c. 1st generation: F1 (first filial)

  7. 6. conclusions: a. biological inheritance is passed from one generation to the next 1) chemical factors that determine traits: genes

  8. 2) genes controlled by 2 different characteristics per trait: allele ex. Height – short/tall

  9. b. Principle of Dominance: some alleles are dominant & some recessive. 1) upper case= dominant ex: A 2) lower case= recessive ex: a

  10. 7. Did the recessive alleles disappear? p. 261, 274 a. F1 crossed short & tall plants= all tall b. F2 self-pollination 1) ¼ of F2 generation showed recessive trait

  11. 8. Law of segregation: 2 alleles will separate during gamete formation. p. 264 9. Law of independent assortment: genes for different traits will sort independently. ex: blue eyes/blonde hair

  12. II. Probability & Punnett Squares • Principle of probability can be used to predict outcomes of genetic crosses. • What is the probability that a tossed coin will come up heads?

  13. B. Punnett squares show gene combination that might result from a genetic cross. 1. Reginald Punnett 2. follows Mendel’s segregation principle

  14. 3. Homozygous a. 2 identical alleles for a trait. ex: AA, aa b. true breeding

  15. 4. Heterozygous a. 2 different alleles for a trait ex: Aa b. hybrid

  16. 5. Phenotype: a. physical characteristic ex: brown hair 6. Genotype: a. genetic makeup ex. DNA

  17. 7. Monohybrid cross: 1 trait ex: AA x Aa (p. 266, 276) A A AA AA A Aa Aa a

  18. 8. Dihybrid cross: 2 traits (p. 267, 187) ex: TtYy x TTYY (Tt) (Yy) = TY, Ty, Yt, ty (TT) (YY) = TY, TY, TY, TY

  19. TY Ty tY ty TY TTYY TTYy TtYy TtYY TY TTYY TtYY TtYy TTYy TTYY TtYY TtYy TY TTYy TY TTYY TtYY TtYy TTYy

  20. III. Beyond Dominant & Recessive Alleles • Incomplete Dominance: one allele is not completely dominant over the other. • 1. F1 generation of four o’clock plants:

  21. red-flowered (RR) and white-flowered (WW) • offspring (RW): pink-colored flowers = x

  22. B. Codominance: both allels contribute to the phenotype of the organism. 1. Roan cows – have both red and white hair; some can look pink

  23. 2. Sickle-cell anemia: homozygous, hemoglobin forms crystal-like structures that change the shape of the RBC.

  24. a. cause slow blood flow, blockage, tissue damage & pain b. anemia: low # of RBC

  25. C. Multiple Alleles: a gene could have more than 2 alleles. 1. coat color in rabbits

  26. Full color: CC, Ccch, Cch, Cc Chinchilla: cchcch, cchch, cchc Albino: cc Himalayan: chch, chc

  27. 2. Blood types p. 331 a. determined by presence or absence of certain protein on surface of RBC b. Phenotype A: Ia is dominant to i

  28. c. Phenotype B: Ib is dominant to i d. Phenotype AB: Ia & Ib are codominant. e. Phenotype O: i allele is recessive & no surface protein

  29. f. Rh factor 1. Rh positive: Rh+/Rh+, Rh+/Rh- 2. Rh negative: Rh-/Rh- 3.Parents donate 1 Rh factor

  30. D. Polygenic Traits: traits controlled by 2 or more genes. 1. skin color in humans – 4 diff. genes control trait

  31. IV. Meiosis • Diploid vs. haploid • Homologous chromosomes • 2 cellular divisions • Genetic recombination

  32. E. Meiosis I 1. Prophase I: a. crossing over b. tetrad F. Meiosis II 1. very similar to mitosis

  33. G. Mistakes 1. Nondisjunction: failure of homologous chromosomes to separate

  34. 2. Trisomy: gamete with an extra chromosome is fertilized by a normal gamete. a. Klinefelter Syndrome 3. Zygote with an extra 21st chromosome: Down Syndrome

  35. 4. Monosomy: gamete with a missing chromosome is fertilized with a normal gamete. a. usually do not survive b. Turner’s syndrome

  36. 5. A gamete with an extra set of chromosomes is fertilized by a normal haploid gamete: triploid ex. Apples (3n)

  37. 6. Organisms with more than the usual # of chromosome sets are called polyploidy. ex. Day lily a. flowers & fruits are larger & plant healthier

  38. V. Human Heredity • Karyotype: picture of chromosomes arranged in pairs from largest to smallest.

  39. Used to see chromosomal abnormalities or genetic disorders. • 44 or 22 pairs of chromosomes are autosomes.

  40. 3. 2 of the 46 chromosomes are sex chromosomes a. 46XX; 46XY

  41. 4. Additional abnormalities: a. Cri-du-chat

  42. b. Williams Syndrome 1) fluorescent in situ hybridization, or FISH

  43. c. Reciprocal Translocation: Philadelphia Chromosome

  44. d. Robertsonian Translocation

  45. Find cause, symptoms, treatment for: • Klinefelter Syndrome 9. Tay-Sachs • Turner’s syndrome 10. Cri-du-chat • Williams Syndrome 11. Phenylketonuria • Philadelphia Chromosome • Robertsonian Translocation • Cystic Fibrosis • Huntington’s Disease • 8. Sickle-cell Anemia

  46. B. Pedigree Chart: shows relationships within a family. Key: male female carrier affected

  47. Sex-linked traits: traits controlled by genes located on sex chromosomes. • Thomas Morgan • 1) Fruit flies

  48. eye color located on X What can we conclude? eye color located on X

  49. b. Color blindness, muscular dystrophy, & anemia

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