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. 90. Independent assortment Monohybrid cross True breeding Cross pollination Self pollination Alleles Homozygous dominant Heterozygous Homozygous recessive Genotype Phenotype 101. 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 • Do you remember these? • Trait: characteristic of an organism. • Gene: piece of DNA that codes for a protein. • Allele: different forms of a gene. • Phenotype- observable feature 9eye color, hair color, blood type) • Genotype- arrangement of alleles (Aa, Tt, Bb Gg)

11. Useful Terms • Do you remember these? • P generation (parental): true breeding • F1 (first filial) offspring of P generation • F2 (second filial) offspring from F1 cross

12. 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

14. Floral Anatomy • pollination • fertilization

15. Floral Anatomy

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

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

20. 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.

21. 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.

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

23. Tongue Rolling

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

27. Data summary from dihybrid lab

28. Data summary from dihybrid lab

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

30. 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

31. 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%

32. 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

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

34. GG x Gg

35. Gg x gg

36. Gg x Gg

37. 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:

38. 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:

39. 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?

40. 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

41. 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.

42. 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

43. 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

44. PTC tasting

45. Reality Show? • Do you recognize this family? • *Hint: They are from a TV show

46. They are the Roloff family from TLC’s show Little People Big World How are the members of this family the same? How are they different?

47. Great! You probably noticed that the family members share facial features, hair color etc. They are different because of their height Some family members (including the parents) exhibit the characteristic short stature of Achondriplasia, a dominant genetic disorder that results in a form of dwarfism.

48. How is it possible for Matt and Amy (the parents) to have a child like Zach with Achondriplasia and three children who do not have the disease?

49. The key is understanding dominant and recessive genes and the concept of segregation

50. Zach Jeremy Zach and Jeremy are Fraternal Twins – what does that tell us about their genes? Fraternal twins have genes that are different - genetically, they are no more similar than any other set of siblings. If Zach and Jeremy were Identical Twins, how would this picture change? Both boys would either display the short stature of Achondriplasia or be of normal height – Identical twins have identical genes!