FUNDAMENTALS OF GENETICS

1. FUNDAMENTALS OF GENETICS USEFUL MATERIALS Video- Garden of Inheritance Guinea Pig Work sheet Text pages 159-176 Worksheet and word search

2. 75. Independent assortment Monohybrid cross True breeding Cross pollination Self pollination Alleles Homozygous dominant Heterozygous Homozygous recessive Genotype Phenotype Test cross Read: 159-170 Vocabulary

3. Remember this about chromosomes? • X = shorthand for chromosomes • 46 total – 23 from mom and 23 from dad (23 pairs) centromere Chromatids (2)

4. Types of Chromosomes • Autosomes – do not determine sex (1-22) • Sex Chromosomes – determine sex (X and Y) = 23rd • XY – male • XX - female

5. Hereditary Terms • Trait – genetic characteristic of an organism • Gene – DNA sequence that codes for a protein (may lead to a trait) • Allele – different forms of a gene

6. I. Principles of Heredity • There are two factors which determine what and who you are, or what an organism looks like and how it behaves. • HEREDITY - the genetic make-up • ENVIRONMENT- conditions during development • Is it “NATURE OR NURTURE” that determines the ultimate product? • Studies on TWINS are inconclusive

7. II. PARADOX OF HEREDITY • A paradox is a seeming contradiction. • “Success is measured sweetest by those who never succeed.” – Dickens • “We are most lonely at times when we are among many men” H. D. Thoreau • Consider a situation in which a father and his son are driving down the road. The car collides with a tree and the father is killed. The boy is rushed to the nearest hospital where he is prepared for emergency surgery. On entering the surgery suite, the surgeon says, "I can't operate on this boy. He's my son."

8. So what is the paradox of heredity? • Why are some characteristics inherited exactly and others are variable? • Species Characteristics: 5 fingers, walk erect, nervous system, appendix, 2 eyes • Individual Characteristics: height, hair color, skin color, hair line

9. Diagram 2 homologous pairs of chromosomes with alleles on each pair X X X X

10. Useful Terms • Phenotype- observable feature (eye color, hair color, blood type) • Genotype- arrangement of alleles (Aa, Tt, Bb Gg)

11. III. History • Gregor Mendel: Austrian Monk (1822-1884) • Published the results of scientific research on Garden Peas (Pisium sativum) in 1865. Why study peas? • Great natural variation- stem length, seed color, pod shape ,pod color, small, edible, easy to grow, many offspring, easy to cross fertilize, grow well in tne climate

13. Floral Anatomy • pollination • fertilization

14. Floral Anatomy

15. More Useful Terms • P generation (parental): true breeding • F1 (first filial) offspring of P generation • F2 (second filial) offspring from F1 cross

16. IV. EXPERIMENTAL CROSSES FOR INDIVIDUAL TRAITS Must begin with PURE BREEDING parents: HYBRID offspring F1 First Filia Generation Cross Pollination P yellow X green tall X short wrinkled X round F1 yellow tall round these are TEST CROSSES to determine dominance and recessiveness

17. P yellow X green F1 yellow allowed to Self Pollination F1 yellow X yellow Tall X Tall Round X Round F2 3 yellow 1 green 3 tall 1 short 3 round 1 wrinkled **Large sample sizes are needed to get an accurate picture of the frequency P red X white F1 red (self) F2 705 red 224 white

18. V. PUNNETT SQUARE Method for determining possible allele combination for the offspring Gametes outside Offspring Inside

19. Who was Punnett? • REGINALD CRUNDALL PUNNETT (1875-1967)was among the first English geneticists. He created the “Punnett Square” – a diagram to work out the possible allele combinations of the offspring of two parents.

20. How are gametes produced? • Meiosis! • Where does this process happen in a flower? • If a person is a tongue roller with the genotype Tt, what happens to the alleles during meiosis? Draw the process.

21. Draw summary and short hand of meiosis with 1 pair of chromosomes

22. Tongue Rolling

23. X X Chromosomes with alleles Gene: tongue rolling Alleles: T- can roll t – unable to roll

26. Monohybrid (one feature) Dihybrid (two features) VI. TEST CROSSES

27. Some more terms… • Homozygous Dominant – TT – given two dominant alleles from parents • Homozygous Recessive – rr – given two recessive alleles from parents • Heterozygous – Gg – given one dominant allele and one recessive allele from parents

28. Setting up a Punnett Square • Brown eyes (B) are dominant to blue eyes (b) • Cross a homozygous brown-eyed person with a blue-eyed person • BB vs. bb B B b Bb Bb b Bb Bb What is the probability of having an offspring with heterozygous brown eyes? 4/4 or 100%

29. Another Example • Tongue rolling(T) is dominant to non-tongue rolling (t) • Cross a homozygous tongue roller with a heterozygous tongue roller • TT vs. Tt T T T TT TT t Tt Tt What are the genotype possibilities? 2/4 or 50% TT and 2/4 or 50% Tt

30. Useful Terms • Phenotypic ratio- Pattern of offspring distribution according to phenotype Usually written as a fraction. observable feature (eye color, hair color, blood type) • Genotypic ratio- Pattern of offspring distribution according to genotype. Usually written as a fraction. • arrangement of alleles (Aa, Tt, Bb Gg)

31. Practice Problems • Pea Plants: green – G yellow – g • GG x gg • GG x Gg • Gg x gg • Gg x Gg Genotypic/phenotypic ratios:

32. GG x Gg

33. Gg x gg

34. Gg x Gg

35. Albinism is the result of the expression of a recessive allele for skin pigment There are several forms of albinism

36. A normal pigmented male (who has an albino mom) and an albino female get married and have two children. What are the phenotypic ratios and genotypic ratios? What alleles will you use? Genotypic Ratio: Phenotypic Ratio:

37. Some more practice problems: • Two “normal” heighted but heterozygous people have a child who is a midget. The wife is pregnant. What is the chance that their second child will be of normal height? What alleles will you use? Genotypic Ratio: Phenotypic Ratio:

38. Dimples is a dominant trait. A heterozygous mom and a homozygous recessive dad have a child. What is the phenotypic ratio and genotypic ratio of the possible offspring? What is the genotype and phenotype of the parents?

39. Finding phenotypes and genotypes for 2 traits. • Read lab • Observed ratio- a record of the results of an event that has occurred • Expected ratio- mathematically calculated results of an event prior to it occurring

40. Finding phenotypes and genotypes for 2 traits. • Chance- not planned, accidental, not expected • Sample Size- number of events recorded large sample side is needed to reduce the influence of chance and allow the true patterns to emerge.

41. Dihybrid Cross Cross 2 pea plants that are both heterozygous purple flowered and heterozygous for smooth seeds. P= purple p= white N= non-wrinkled (smooth) n= wrinkled • Step 1: Figure out the different gametes for each parent • Step 2: Set-up the cross and complete • Step 3: Calculate the genotypic and phenotypic ratios

42. Example of Ratios

43. Data summary from dihybrid lab

44. Data summary from dihybrid lab

45. VII. Mendel’s Laws Mendel was a patient and keen observer. • Some characteristics mask others yet reappear. • Principle of Dominance and Recessiveness • Features can skip a generation. • Theorized there were 2 factors for each trait. • Principle of Segregation of Alleles • Pairs of factors separate into gametes without influenceing each other. • Principle of Independent Assortment

46. Quiz Topics –FRIDAY 3/5 Read: 159-170 • Vocab 90-101 • Worksheets (pg 127 and pg 129) • Mendel and his laws • Terminology (P, F1, F2, heterozygous, homozygous dom, homozygous rec, phenotype, genotype, trait, gene, allele) • Monohybrid vs Dihybrid crosses • Doing monohybrid problems

47. Review Questions • RRTT • RrTt • RRtt • Rrtt • List gametes possible from these parents

48. (T) is the allele for tall humans and is dominant over the allele (t) for short humans. The allele for widows peak (W) is dominant over (w) non-widows peak hairlines. What are the phenotypes for the following parents? TtWw - _________________ TTww - _________________ What are the possible gametes formed by the parents listed above? AND

49. 1. A woman with free ear lobes marries a man with attached ear lobes. Two of their children have attached ear lobes and two have free ear lobes. The alleles are (E) - free (e) - attached • A. what is the genotypes of the woman? • B. what is the genotype of the man? • C. What are the chances of the 5th child having free ear lobes?

50. (F) striped fur is dominant over (f) white fur in Australian cats. What is the result of a cross between a homozygous recessive parent and a heterozygous parent? Give phenotypic ratios and genotypic ratios. Genotypic Ratio: Phenotypic Ratio: