Genetics- the Study of Heredity

1. Genetics- the Study of Heredity Early Genetic Philosophy 300 B.C.- 1600 A.D. Abiogenesis- living things rise out of non- living things.(Spontaneous Generation)

2. Abiogenesis • Rotten logs -> snakes , moss • Horse hair -> worms and eels • Mud -> frogs and toads • Dead meat -> flies • Horse sweat -> fleas and lice

3. Abiogenesis Recipe for mice and rats - 1 lb. of wheat grains - 1 dirty shirt Leave in dark closet for two weeks.

4. Biogenesis- life from other life 1600’s(invention of microsope) Something in the cell causes new life. 1st hypothesis= Homunculus- little person in head of sperm cell.

5. Biogenesis Studies by Pasteur, Virchow, and Redi proved that there was something in the nucleus of both sperm and egg!

6. 1800’s Microscopes Improve! Chromatin grains turn into Chromosomes when cell divides! nucleus nucleus

7. Mitosis-body cell divides to form 2 new body cells. Both homologous chromosomes in both cells. Meiosis-sex cells(1/2 the number of chromosomes, only one homolog from a pair) form from cells in sex organs. 2 Types of Cell Division

8. Time for Terminology • Homologous- related chromosomes or genes. One from mom, one from dad • Haploid- cells having only one of each homolog(sperm and egg). • Diploid- cells having both homologs. (all body cells)

9. Mitosis and Meiosis • Mitosis allows for genetic continuity within an organism. • Meiosis allows genetic variety during sexual reproduction.

10. Time for Terminology • Karyotype- a picture of all of the chromosomes arranged in pairs

11. Time for Terminology • Genome- a list of all the genes on all of the chromosomes.

12. Time for Terminology • Genes- section of a chromosome which contain DNA for one trait. • Alleles- all the different forms of one gene. (ex. blue, green eyes etc.) video

13. Blond Hair Blue Eyes Tongue Roller Brown Hair Blue Eyes Non- Roller One from Ma, one from Pa

14. Time for Terminology • Dominant- a gene that shows up as a trait even when only one is present. • Recessive- a gene that will always “lose” to the dominant gene. Only shows when both genes are recessive.

15. Time for Terminology • Pure Dominant- the homologs both carry a dominant gene. • Pure Recessive- the homologs both carry a recessive gene. • Hybrid- the homologs carry different genes.(one of each)

16. Time for Terminology • Genotype- the two genes that code for your trait. (ex. Bb, tt) • Phenotype- the trait that a genotype actually gives you. (ex. blue eyes, non tongue-roller) video

17. Time for Terminology • Homozygous- the homologs carry two of the same genes. • Heterozygous- the homologs carry two opposite genes.

18. Too Much, Rholl!!

19. Simplify Please!!!! Punnett Square- technique used to solve genetic problems. Give each allele a letter. Capitol letters for dominant genes and lower case for recessive genes.

20. As Simple as 1, 2, 3 ... • 1. Choose your letters. (ex. B= blue, b= green) • 2. List Ma and Pa’s letters. (ex. = BB , = Bb ) • 3. Fill in the Punnett Square.

21. Sample Problem Tongue rolling is dominant over nonrolling. A homozygous tongue rolling man marries a hybrid woman. What are the chances their baby will be a tongue roller?

22. 2. = Tt = TT Answer: It is 100% certain that their baby will be a tongue roller. 3. Punnett Square T t T TT Tt T TT Tt 1. T= tongue rolling t= non-rolling

23. Incomplete Dominance Some traits there is no dominant gene. The two alleles are equal to each other. A hybrid genotype produces an in between phenotype.

24. Sample Problem In four o’clock flowers, red petals is incompletely dominant to white. What colored flowers might you get if you mated a pure red flower with a hybrid?

25. 2. = RR = RW Answer: 50% of babies will have red flowers, 50%pink. R R R RR RR W RW RW 1. R= red flowers W= white flowers

26. Co-dominant- both traits appear Ex. Sickle Cell Anemia: The gene for normal red blood cells (N) is co-dominant to the gene for sickled cells (S). The hybrid genotype gives you normal red blood cells that may sickle under low oxygen concentrations.

27. Sickle Cell Anemia: Co-dominant Predict the genotype and phenotype ratios of the babies born to a parent that is normal and a parent who is a hybrid.

28. Multiple Alleles Traits Allele- the different choices (forms) a gene can have for a certain trait. Most traits have only two choices, but some have three or more!(bloodtype , eye color)

29. Sample Problem In Adam’s flowers, purple petals are dominant to both yellow and pink. Pink is dominant over yellow.

30. Sample Problem A pure yellow flower mates with a purple flower. The offspring are 16 purple flowers and 17 pink flowers. What are the genotypes of the parents?

31. Sample Problem P1= purple = p p P2= pink = P1__?_ p= yellow p p P1 P1p P1p __ _p _p

32. Blood Types have Multiple Alleles There are 4 main types of blood: A, O, B and AB. What makes them different is the kinds of proteins found on the cell membrane of their red blood cells. Why blood type is important?- Mixing the wrong types of blood together can cause clotting, health problems and possible death. There are 3 blood type genes: A, B and o

33. Sex-linked Traits Some traits are on the X chromosomeand are called sex-linked. The results differ depending on the sex of the baby!

34. Women have 2 X chromosomes, men have one X and one Y. It’s not surprising there are equal #’s of male and females. X X X XX XX Y XY XY It’s Fitty, Fitty!

35. Males don’t have two “matching” chromosomes

36. H g X Y Y chromosomes do not have all the genes that an X chromosome has. You have to write the X and Y! F f

37. Sample Problem Hemophilia is sex-linked and recessive. It is on the X chromosome. A hybrid carrier woman marries a normal man. What are the odds that they will have a girl with hemophilia? A boy?

38. = XX = XY Answer: boys only (1/2). girls could be carriers (1/2) X X X X X X X Y X Y X Y 1. H= normal h= hemophelia

39. Multifactorial Inheritance • Traits caused by more than one gene pair. ex. hair color • One trait effects the expression of another trait. ex. hair/skin color • The environment has an effect on certain traits. ex. skin color

40. Pre-Natal Screening Certain parents may have genetic testing done in the womb if there is a concern of genetic disorders.

41. Newborn Screening All newborns are screened for genetic diseases using a blood test. In MN., we screen for PKU, Sickle Cell, Tay- Sachs, Galactosemia,and hyperthyroidism.

42. Some Genetic Diseases • Sickle Cell Anemia- homozygous recessive, bad red blood cells • Galactosemia- homozygous recessive, can’t digest milk sugar • PKU- homozygous recessive, can’t digest the amino acid, phenylanine • Tay-Sachs Disease- homozygous recessive, can’t digest fat

43. Other Genetic Diseases • Diabetes Mellitus- caused by many genes and environment, inability to produce insulin • Hemophilia- sex-linked recessive, blood clotting problems • Down’s Syndrome- 3 #21 chromosomes , common form of retardation

44. DNA Fingerprinting We are now able to analyze your unique DNA and compare it to others using Restriction Enzymes and Electrophoresis.

45. Everyone has a unique DNA “fingerprint”. • Each person has about 100,000 genes. • Each gene is made up of thousands of nitrogen bases. • The odds of two people having the exact same DNA is 0.(33 0’s)1 %

46. Who would steal from these innocent faces??

47. Restriction Enzymes- chemicals that cut DNA at specific sites • Flush Cut- used for DNA fingerprinting • Sticky Tails- used for genetic engineering and recombinant DNA.

48. Electrophoresis- technique used to seperate DNA segments by size All DNA segments created by restriction enzymes are put in the starting well of an agarose gel box

49. Electrophoresis- seperates DNA segments A steady electric current is applied to the end of the gel box. This causes DNA segments to move in the direction of the current.

50. Electrophoresis- seperates DNA segments Short segments are able to travel farther through the gel than longer fragments.