1. HEREDITY GENETICS

2. HEREDITY Heredity Is the passing of traits from parents to offspring. Genes on chromosomes control the traits that show up in an organism. The different forms of a traits that a gene may have are alleles.

3. Chromosome

4. CELL DIVISION During meiosis a pair of chromosomes separates and the alleles move into separate sex cells. Each sex cell now contains one allele for each trait. The study of how traits are inherited is genetics.

5. Mitosis

6. Meiosis

7. Gregor Mendel the father of Genetics Mendel was the first to use mathematics of probability to explain heredity and to trace one trait for several generations. Hybrid receives different genetic information for a trait from each parent.

8. Mendel and Beans Experiment

9. ALLELES Dominant allele covers up or dominates the other. Recessive allele the trait seems to disappear. Probability helps you predict the chance that something will happen.

10. Dominant and Recessive Allele

11. GENETICS Punnet square can help you predict what an offspring will look like. Upper case letters stand for dominant alleles Lowercase letters stand for recessive alleles. Genotype the genetic make up of an organism.

12. Punnet Square

13. GENETICS Homozygous an organism with two alleles for one trait that are the same ( written TT) Heterozygous an organism with two alleles for one trait that are different ( written Tt) Phenotype the way an organism looks and behaves as a result of its genotype.

14. Phenotype

15. Genotype

16. Genetics since Mendel Incomplete dominance Neither allele for a trait is dominant. The phenotype produced is intermediate between the two homozygous parents. Multiple alleles More than two alleles that control a trait are called multiple alleles. Traits controlled by multiple alleles produce more than three phenotypes.

17. Incomplete Dominance

19. Polygenic Inheritance A group of gene pairs acts together to produce a trait, which creates more variety in phenotypes. Many human traits are controlled by polygenic inheritance, such as hair and eye color.

20. Polygenic Inheritance

22. MUTATIONS Mutations are genes that are altered or copied incorrectly. A mutation can be harmful, beneficial or have no effect. Chromosome disorders caused by more or fewer chromosomes than normal. Down’s syndrome caused by an extra copy of chromosome 21.

23. Normal Karyotype

24. Trisomy 21

25. Down Syndrome /Trisomy 21

27. Cleft Lip and Palate

28. Trisomy 18

30. Trisomy 18/Edwards Syndrome

31. Recessive Genetic Disorders Both parents have a recessive allele responsible for the disorder and pass it to their child. Because the parents are heterozygous, they don’t show any symptoms. Cystic Fibrosis is a homozygous recessive disorder.

32. Cystic Fibrosis

35. Hutchinson–Gilford Progeria Syndrome

36. CAUSE The gene LMNA encodes a protein called prelamin A. Prelamin A has a farnesyl group attached to its end. Farnesyl group is removed from prelamin A. Farnesyl group remains attached to prelamin A. Normal form is called prelamin A. Abnormal form of prelamin A is called progerin. Prelamin A is not anchored to the nuclear rim. Progerin is anchored to the nuclear rim. Normal state of the nucleus. Abnormally shaped nucleus.

37. Sex Determination Chromosomes that determine the sex of an organism are XX in females and XY in males. Females produce eggs with an X chromosomes only. Males produce sperm with either an X or a Y chromosome.

38. Sex-linked disorders An allele inherited on an X or Y chromosome is a sex-linked gene. Color blindness is a sex- linked disorder caused by a recessive allele on the X chromosome. A pedigree follows a trait through generations of a family.

39. Advances in Genetics Genetic Engineering is changing the arrangement of DNA that makes up a gene. Recombinant DNA. Insertion of a useful segment of DNA into a bacterium. Insulin is a made by genetically engineered organisms.

40. Gene therapy A normal allele is placed into virus, which delivers the normal allele when it infects its target cell. May be used to control cystic fibrosis or other genetic disorders. Genetically engineered plants created by inserting the genes that produce desired traits in one plant into a different plant.

41. Sex- linked trait on the X chromosome is color blindness Xc Normal female Normal male Carrier female Color-blind male

42. Sex-linked chromosome

43. Questionnaire 1. What is the genotype of the first generation female person 4 ? Xc X 2. What is the genotype of the first generation male, person 5 ? Xc Y 3. What is the probability in percent of person 6 passing on the color-blind trait ? 0 %

44. Questionnaire 8. What is the probability in percent of person 7 passing on the color-blind trait? 50 % 9. Person 5 is color-blind. However, his sons do not have this condition. What accounts for this? Sons inherited only the Y chromosome from their father.