Topic : Genetics Aim : Explain the basic principles of genetics.

1. Topic: Genetics Aim: Explain the basic principles of genetics. Do Now: What is the meaning of the term “heredity?” HW: Read p. 129. Write a one PARAGRAPH summary about Mendel’s experiment. DO NOT COPY WORD FOR WORD! PUT IT IN YOUR OWN WORDS.

2. A characteristic of an organism Ex: Hair color, eye color, height, skin color… Trait

3. Genetics • The study of heredity (passing on of traits to offspring)

4. Gregor Mendel • Father of Genetics • Studied how traits are passed on from one generation to next

6. Used PEA PLANTS

8. Genes • Units of heredity (DNA) found on chromosomes

9. 2 genes (ALLELES) for every trait • 1 from each parent Gene from dad Gene from mom

11. Dominant Allele • “Stronger” gene • Capital letter • Example: T = tall pea plant

12. Recessive Allele • “Weaker” gene • Lower case • Example: t = short pea plant

13. DOMINANT RECESSIVE

14. RECESSIVE DOMINANT

15. Phenotype • Physical appearance • Tall, short, blue eyes, brown eyes…

16. Genotype • Genetic Makeup

18. Gene Combinations

19. Tall Pure dominant OR Homozygousdominant TT + T T TT

20. tt • Short • Pure recessive OR Homozygous recessive + t t tt

21. Tt • Tall • Hybrid OR Heterozygous • *ALWAYS SHOWS DOMINANT TRAIT + t Tt T

22. Example: G = green seeds, g = yellow seeds • Give 3 possible gene combos with phenotypes & genotypes.

23. GG, gg, Gg • GG • Phenotype = green • Genotype = • Homozygous dominant or pure dominant

24. gg • Phenotype = yellow • Genotype = Homozygous recessive or pure recessive

25. Gg • Phenotype = green • Genotype = hybrid or heterozygous

26. W = widow’s peak w = straight hairline

27. P = bent pinkie p = straight pinkie (cannot bend inwards)

28. E = attached earlobes e = unattached earlobes

29. R = Rolling of the tongue • r = cannot roll tongue

30. C = Cleft chin c = smooth chin

31. D = Dimples d = Without dimples

33. Let’s summarize… • Explain what is studied in genetics. • Who is the father of genetics? What did he use in his experiments? • How many genes (alleles) are needed for every trait? • Explain the difference between a dominant and recessive gene. • Explain the difference between genotype and phenotype.

34. Sometimes tens, or even hundreds of genes can play a role in just one trait! Melanin, a brown pigment, is controlled by the following genes: brown-blue gene on chromosome 15 green-blue gene on chromosome 19 Another brown-type gene was also discovered on chromosome 15. Recently, a gene for a brownish yellow pigment, lipofuscin, that appears in amber, green and violet irises was discovered. And there's likely at least one other gene, not yet located, that plays a role in iris color.

35. Goldfish have 96 chromosomes in each cell while humans only have 46. Dogs have 78 chromosomes. And here’s the real shocker, a fern has 512 chromosomes.

37. Take a close look at your fingertips. You can easily see that the skin is folded into patterns. These patterns are called dermal ridges, forming whorls, arches and loops. For the most part, the number of dermal ridges in a fingerprint pattern is determined by genetics, but the pattern can also be changed early in pregnancy. During weeks 6-13 of prenatal development, the fetus touches the finger and toe pads to the wall of the amniotic sac which sometimes can alter the ridge pattern. This explains why the fingerprints of identical twins are not exactly alike, even though they have identical genes.