Gene, chromosome,DNA

1. Gene, chromosome,DNA DNA

2. Patterns of Inheritance • Complete Dominance • Incomplete Dominance • Codominance • Pleitrophy • Epistasis • Multiple Alleles • Polygenic • Sex Linked • Sex influenced • multifactorial

3. Blending theory • Genetic materials are like liquids Particulate theory Hereditary units are discrete units or genes

4. Mendel • Made genetics quantifiable • Experimental crosses • Character- detectable inherited feature • Trait-variation of a character

5. True breeding or pure bred- always produced the same trait • Hybrids produced different variants WHY

7. Nature vs Nurture • What role is played by genetics? • What role is played by the environment?

8. A a AA aa a A A a Gametes (A,a) segregate a A A a

9. Principles of Heredity • Alternative versions of genes (alleles) account for variations in a trait. • For each character, an organism inherits two alleles, one from each parent. • If alleles differ, then the dominant will be fully expressed over the recessive. • The two alleles segregate (separate) during gamete formation. • Alleles on different chromosomes segregate independently of one another

10. Independent Assortment and Segregation a A B b For an organism of the genotype AaBb

11. Meiosis results in the following:

12. Independent Assortment and Segregation A a ab AB b B For an organism of the genotype AaBb

13. Independent Assortment and Segregation a A AB ab B b For an organism of the genotype AaBb

14. Independent Assortment and Segregation A a aB Ab B b For an organism of the genotype AaBb

15. Independent Assortment and Segregation A a ab AB b B For an organism of the genotype AaBb

16. Calculate the posssible gametes from the following crossesBbHh, DDHh, BbDd, bbhh • BH, Bh, bH, bh • DH,Dh • BD, Bd, bD, bd • bh

17. Genetic Crosses and Problems • Monohybrid • Dihybrid • Pedigree

18. Monohybrid Cross-consider onlyone trait Gametes Offspring F1 Gametes

19. Monohybrid Cross-consider onlyone trait Gametes Offspring F2 Gametes Genotypic ratio 1 : 2 : 1 Phenotypic ratio 3 : 1

20. Law of Multiplication of Probabilities • Bb ½ B or ½ b XBb ½ B or ½ b 1/4BB + 1/2Bb + ¼ bb

21. BB ½ B or ½ B XBb ½ B or ½ b ½ BB + ½ Bb

22. Dihybrid cross-cross two traitsheterozygous black wings BbWw X BbWw Phenotypic Ratio 9:3:3:1

23. Crossing over During prophase of meiosis homologous pairs may exchange genetic material. TETRAD or synapsis

25. New Genetic Combinations • Recombination during fertilization brings together two sets of genetic instructions • Meiosis-crossing over brings about new combinations • Random genetic mutation can result in random genetic change

26. Autosomal Complete Dominance b b • One gene is able to dominate the other recessive allele • Example all offspring express B as black fur over b white B Bb Bb B Bb Bb All black offspring

27. Autosomal Dominant • Huntingtons Disease • Achondroplasia • Certain Form of Breast Cancer

28. Galactosemia, Albinism • Sickle cell Anemia • Cystic Fibrosis • Tay-Sachs • PKU-phenylketonuria

29. Autosomal Dominant Patterns

30. Autosomal Recessive Pattern Gene is unable to express itself unless it is in a homozygous condition.

32. C c CC Cc ? ? C c Cc c c

33. Incomplete dominance- both genes are expressed as intermediate forms

34. RR-red, WW-white RW-pink R R RW W RW W RW RW

35. Red crossed with white results in pink flowers R R RR’ RR’ R’ RR’ RR’ R’

36. Incomplete dominance • Both genes are unable to be expressed ,the heterozygote is intermediate in expression R’ R R’ R R’ R’ R’ R R’ R R R

37. CODOMINANCE- each gene of the allele is expressed iA iA The A,B, O Blood type shows Codominance genotypes iAiA, iBiB, iOiO, iAiB, iAiO ,and iBiO iAiB iAiB iB iAiB iAiB iB

38. Blood Groups Type Genotypes

40. Multiple Alleles • In this pattern more than two alleles are possible for a trait. • Blood Groups or types are an example of this also.

41. Blood Groups Type Genotypes

42. What about RH Factor • Single dominant gene produces an RH antigen labeled + • RH negative individuals are homozygous recessive - -

43. Polygenic • More than one pair of genes control the trait • Genes working together • Expression is varied • Race is an example • Most common form of inheritance

44. Pleitrophy • A gene which affects an organism in many ways • Multiple phenotypic effects • Ex. Sickle-cell anemia, albinism

45. Epistasis • A gene at one location alters the phenotypic expression of another gene • Coat color in some mammals

46. Polygenic Inheritance • Additive effect of two or more genes on phenotypic expression • Phenotypic expression varies along a continuum • Skin and eye pigmentation

47. Multifactorial • Influenced by both environment and heredity

48. Sex or X linked Inheritance- genes that are carried on the X chromosome

49. Barr Bodies • When multiple X chromosomes are present one or more will be inactivated leaving only one • The inactive X forms a dark staining Barr body • Random inactivation can result in mosaics

50. Sex-Linked Disorders • Genes carried on the X chromsome • Males only have one- more likely to have trait • Females can be carriers • Most important diseases are recessive