Chapter 11,13 & 14 Genetics

1. Chapter 11,13 & 14Genetics (Or why you really shouldn’t date your cousin, and especially your sister)

2. The Beginnings….. • Heredity: biological inheritance, the passing of genetic traits from one generation to the next • Genetics: the biological study of inheritance

3. Background... • Blending Inheritance: the blending of traits in the offspring: • Tall + short = medium offspring • Disproved by Gregor Mendel, a really boring monk • Came up with 5 laws of Inheritance, well sort of

4. Mendel’s Genetics: • Used math to prove inheritance • Studied pea plants using self-pollination of purebred pea plants • Followed traits for 3 generations to see how traits appear and disappear • P (parents), F1 (first generation), and F2 (second generation, from F1 cross)

5. Mendel’s Genetics:

6. Mendel’s Laws of Inheritance • 1. Unit Characters: individual factors control traits, these factors are called genes • Trait: Characteristic • Allele: different forms of a gene, Tall or short, same gene, T or t

7. 2. Dominance • Some factors are dominant over others, some are recessive. If the dominant is present, it will always show! • Example is Brown eyes over blue

8. 3. Segregation • Individual alleles separate during meiosis (one allele from each parent) • Phenotype: the physical characteristic • Genotype: the genetic make-up of a characteristic

9. The Genotype is described by two terms • Homozygous: two identical alleles, also called purebred • TT or tt, BB or bb • Heterozygous: two different alleles, called hybrid • Tt, Bb

11. 4. Independent Assortment • Individual traits sort independently. • Example is that height does not depend on eye • Allows for a two factor cross

13. 5. Incomplete Dominance • If genes are not dominant or recessive, they mix. • Example is 4o’clock flowers • Red flower crossed with a white flower = a pink flower • RR x rr = Rr

16. A few side notes…… • Codominance: a condition in which both alleles of a gene are expressed. (Hair color in cows) • Polygenic Inheritance: A single trait controlled by more than one gene (hair color, eye color)

17. In order for all this to work……. • Organisms can only inherit a single copy of a gene from each parent • Will replication and mitosis do the trick? • No…..We need…..

18. Meiosis • Meiosis is the process of reduction division in which the number of chromosomes per cell is cut in half and homologous chromosomes that exist in a diploid cell are separated. • Basically, it is mitosis that happens two times to make 4 daughter cells with a haploid chromosome number. • Meiosis animation 1, 2, 3, 4, 5, 6

19. Applying Mendel’s Genetics Probability: the likelihood that a particular event will occur. It is figured by number of times something occurs, by the total number of opportunities Figure by using Punnett Square

20. Tt x Tt Cross

21. Tt X TtCross

22. Gene linkage • Some genes do not undergo independent assortment, these genes are said to be linked. • Genes that are inherited together. • Early studies by Morgan with the fruit fly • Basic Types:

23. Sex Linkage • Genes that are linked and inherited according to your sex • On 23rd chromosome • Secondary sex characteristics, verbal and spatial tendencies

24. Linkage Groups • Packages of genes that are always inherited together • Located on chromosomes other than the sex chromosomes.

25. Crossing Over • Explain recombinants (individuals with new combinations of genes ) • If two homologous chromosomes were positioned side by side, sections of the two chromosomes might cross, break, and reattach. • Occurs during first meiotic division

26. Sex Determination • From the process of Meiosis • 23rd chromosome • Genes on sex chromosome are said to be linked

27. Mutations • Mistakes in the transmission of the genetic information • 1 in 1,000,000 genes are mutated • types: • Chromosomal • Gene

28. Chromosomal • Involve segments, whole, and entire sets of chromosomes, it is a change in the number and structure of chromosomes • Basic types:

29. Deletion: the loss of a part of a chromosome • Duplication: the addition of a part of a chromosome • Inversion: a reverse of a part of a chromosome • Translocation: Crossing over of two chromosomes

30. NonDisjunction: whole chromosome mutations, it is a failure to separate during meiosis • Too many chromosomes: called polyploidy • Trisomy: (2n+1)Downs Syndrome • Too Few Chromosomes: from the left over gametes • Turner’s Syndrome: (2n-1)

31. Gene Mutations • Mutations that result from a change involving many nucleotides within a gene, some may involve only one nucleotide • Point mutations: smallest change, effect single nucleotide

32. Frameshift mutation: when a point mutation single base is inserted or deleted, shifting the entire codon, this changes every codon following the mutation.

33. Beneficial Mutations • Mutations that benefit an organism for fitness • Short sheep in Ireland • Skin on a bulldog

34. Human Heredity • Heredity vs. Environment: Which has a greater effect on the expression of traits • Himalayan rabbit • Size

35. Disorders • Nondisjuction disorders • Downs syndrome-moon child • Kleinfelters Syndrome-sterile male, XXY • Turners syndrome- appear female, X

36. Sex Linked Genetic disorders • From genes on X & Y chromosome • Why do most show in males? • You need homozygous recessive to show in females, due to size difference.

37. Colorblindness: on X chromosome, 1% of women, 8 % of men, most common type is red- green. Color vision is on x chromosome • Hemophilia: Bleeders, recessive on X, missing clotting agent • 1 in 10,000 males, 1 in 100,000,000 females

38. Muscular Dystrophy: the wasting away of skeletal muscle, is carried on X chromosome

39. Autosomal Genetic Disorders • Huntington’s Chorea: Dominant disorder, deterioration of body from interior to exterior • Multiple Sclerosis: recessive • Sickle Cell Anemia: recessive • Allergies: recessive

40. Diagnosis of Genetic Disorders • Pre-Natal: • Amniocentesis: removal of a small amount of fluid from around the embryo, some disorders from biochemical abnormalities (Tay sachs), others from a karyotype (Downs Syndrome) • Ultrasound: can see kidney, heart, bone disorders, spina bifida

41. Diagnosis of Genetic Disorders • Pre-Natal: • Chorionic villus sampling (CVS): suction off a portion of the fetal tissue from the placenta. Because these cells are reproducing so quickly, enough cells in mitosis to do a quick karyotye, results in 24 hours

42. Diagnosis of Genetic Disorders • Newborn Screening • Some genetic disorders can be detected at birth by a simple test for chemicals or reflexes. • PKU, Fragile X, Mental Retardation

43. Genetic Engineering • Modifying the living world in an attempt to make it better • Accomplished by breeding and engineering • Breeding is done by selecting the most productive plants or animals to produce the next generation, you can increase productivity

44. Genetic Engineering • The manipulation of genes to directly change an organism DNA, in humans this technique is use to find cures and diagnose childhood disease. In plants, it us used to manufacture produce that is bigger and better

45. Breeding • Selective: choose the best, multiply • Inbreeding: crossing individuals with similar characteristics, problems are massive recessive traits and mutations

46. Hybridization: Also called outbreeding, crossing two individuals with dissimilar characteristics. The offspring tend to be stronger than parents (Hybrid-Vigor). The offspring is generally sterile, the example is the mule

47. Genetic Engineering Techniques • Restriction Enzymes: proteins that cut DNA at specific sequences • DNA Recombination: The use of a vector to incorporate DNA into another cell, sometimes done with plasmids

49. Genetic Engineering Techniques • DNA Insertion: cloning, inserting copies of DNA into cells, then growing cells with new code. Use needle to inject, or a bacteria cell that will conjugate with another cell