Bell Ringer 12/2/13 Create a vocab chart on a new sheet of paper

1. Bell Ringer 12/2/13Create a vocab chart on a new sheet of paper

2. Genetics • http://www.youtube.com/watch?v=B_PQ8qYtUL0

3. Genetics Using Punnett Squares

4. Early Genetics • The study of genetics began with observations made by Gregor Mendel. • After noticing that the flowers his pea plants were either violet or white, Mendel began to study the segregation of heritable traits. Between 1856 and 1863 he cultivated and tested at least 28,000 pea plants. Remember that Mendel worked almost 150 years ago when nobody knew about genes or even the structures (chromosomes) that carry genes.

5. Here are some traits observed by Mendel:

6. Mendel’s Conclusions • Law of segregation – • every individual has 2 forms (alleles) of a gene and when sex cells (gametes) are produced each gamete produced receives one of these alleles • Law of Independent Assortment • Genes of individual traits are inherited independently of each other • Ex: gene for eye color is independent of hair color gene

7. Lets consider a single gene… • A gene carries information that determines your traits. Traits are characteristics you inherit from your parents. • Genes are located in chromosomes. • Chromosomes come in pairs and there are thousands, of genes in one chromosome.

8. Continued… • In humans, a cell’s nucleus contains 46 individual chromosomes or 23 pairs of chromosomes. • Half of the chromosomes come from one parent and half come from the other parent. This is a human karyotype representing the 23 pairs of chromosomes in a male Here is the detailed structure of a chromosome

9. Definitions • Allele- discrete version of the same gene • Genotype- the genes of an organism for one specific trait • Phenotype- the physical appearance of a trait in an organism

10. Definitions • Dominant trait refers to a genetic feature that “hides” the recessive trait in the phenotype of an individual. • The term "recessive” describes a trait that is covered over (or dominated) by another form of that trait and seems to disappear. • Homozygous= two alleles that are the same for a trait (Pure) • Heterozygous= two different alleles for a trait (Hybrid)

11. Practice • We use two letters to represent the genotype. A capital letter represents the dominant form of a gene (allele) and a lowercase letter is the abbreviation for the recessive form of the gene (allele). • Example below: P=dominant purple and p= recessive white The phenotype for this flower is violet while its genotype (if homozygous) is PP. The phenotype for this flower is white while its genotype is pp (to be white the flower must have two of the recessive copies of the allele).

12. Punnett Squares • The Punnett square is the standard way of working out what the possible offspring of two parents will be. • It is a helpful tool to show allelic combinations and predict offspring ratios.

13. Before we go further lets review how to set up a Punnett Square… We begin by constructing a grid of two perpendicular lines.

14. Next, put the genotype of one parent across the top and the other along the left side. For this example lets consider a genotype of BB crossed with bb. B B • Notice only one letter goes above each box • It does not matter which parent’s genotype goes on either side. b b

15. Next, fill in the boxes by copying the column and row head-letters down and across into the empty spaces. B B b b b B B b b B b B

16. Punnett Squares • Now that we have learned the basics of genetics lets walk through some examples using Punnett Squares.

17. W w Usually write the capital letter first W W W w W Lets say: W- dominant white w- recessive violet w W w w w Parents in this cross are heterozygous(Ww). Note: Make sure I can tell your capital letters from lowercase letters. What percentage of the offspring will have violet flowers? ANSWER: 25% (homozygous recessive)

18. Red hair (R) is dominant over blond hair (r). Make a cross between a heterozygous red head and a blond. R r r r 50% What percentage of the offspring will have red hair?

19. Let’s try some more… In pea plants, tall pea plants (T) are dominant over short pea plants (t). Construct a Punnett Square for a heterozygous tall pea plant and a short pea plant. T t What are the percentage of phenotypes? t t 50% tall 50% short

20. Black eyes (R) is dominant over red eyes (r) in rats. Make a cross between a homozygous rat with black eyes and a rat with red eyes. R R What is the possibility of a red eye off springs? r r 0% 

21. References • http://www.athro.com/evo/gen/punnett.html • http://www.kidshealth.org/kid/talk/qa/what_is_gene.html • http://brookings.k12.sd.us/biology/ch%2011%20genetics/punnettpractice.ppt#1 • http://www.usoe.k12.ut.us/CURR/Science/sciber00/7th/genetics/sciber/punnett.htm • http://www.biotechnologyonline.gov.au/images/contentpages/karyotype.jpg

22. Bell Ringer 12/3/13Add these terms to your vocab chart: • Hybrid • Allele • Dominant • Recessive • Phenotype • genotype • Homozygous • Heterozygous • Law of segregation • Law of Independent Assortment These terms will be checked on Thursday during the bell ringer

23. HeterochromiaIridum http://images.search.yahoo.com/search/images?_adv_prop=image&fr=ytff1-yff24&va=heterochromia+iridum

24. Work with your group to complete the “punnett square practice” worksheet

25. Bell Ringer 12/3/13 Complete your punnett square practice handout pg 2-3 20 min

26. Self-grade your paper • For each of the genotypes (AA, Aa or aa) below determine what the phenotype would be. • Purple flowers are dominant to white flowers. PP - purplePp- purplepp- white

27. AA – homoz dominant • GG – homoz dominant • TT – homoz dominant • Ff – heterozygous • Pp – heterozygous • Tt - hterozygous

28. Aa – heterozygous • Ii – heterozygous • aa – homoz recessive • gg – homoz recessive • tt – homoz recessive • Oo - heterozygous

29. Hairy knuckles are dominant to non-hairy knuckles in humans. HH - hairy Hh - hairy hh - non-hairy • Bobtails in cats are recessive. Normal tails are dominant. TT - bobtail Tt - bobtail tt – normal tail

30. Round seeds are dominant to wrinkled seeds in pea plants. RR - round Rr - round rr – wrinkled • No-cleft chin is dominant. Cleft chin is recessive. CC – no cleft Cc – no cleft cc -cleft

31. 2) For each of the following write whether it is homozygous dominant, heterozygous or homozygous recessive.

32. Use the following information for questions 3-5: • In dogs, the gene for fur color has two alleles. The dominant allele (F) codes for grey fur and the recessive allele (f) codes for black fur.

33. 3) The female dog is heterozygous. The male dog is homozygous recessive. Figure out the phenotypes and genotypes of their possible puppies by using a Punnett Square.

35. 4. The female dog has black fur. The male dog has black fur. Figure out the phenotypes and genotypes of their possible puppies by using a Punnett Square.

36. 5) The female dog is heterozygous. The male dog is heterozygous. Figure out the phenotypes and genotypes of their possible puppies by using a Punnett Square.

37. Use the following information for questions 6-8: • In fruit flies, red eyes are dominant (E). White eyes are recessive (e). •  6) If the female fly has white eyes and the male fly has homozygous dominant red eyes, what are the possible phenotypes and genotypes of their offspring?

38. 7) If the female fly has EE and the male fly has EE, what are the possible phenotypes and genotypes of their offspring?

39. 8) If both flies are heterozygous, then what are the possible phenotypes and genotypes of their offspring?

40. Use the following for questions 9-11: • In dogs, there is an hereditary deafness caused by a recessive gene, “d.” A kennel owner has a male dog (Gilbert) that she wants to use for breeding purposes if possible. The dog can hear. • 9) What are the two possible genotypes of Gilbert? • DD or Dd

41. 10) If the dog’s genotype is Dd, the owner does not wish to use him for breeding so that the deafness gene will not be passed on. This can be tested by breeding the dog to a deaf female (dd). Draw two Punnett squares to illustrate these two possible crosses.

42. 11) In each case, what percentage/how many of the offspring would be expected to be hearing? deaf? How could you tell the genotype of this male dog? Also, using Punnett square(s), show how two hearing dogs could produce deaf offspring.

43. Widow’s peak - dominant No widow’s peak - recessive

44. 12) If Wentworth Miller is Aa, and he and Rihanna had children, what are the possible phenotypes and genotypes of their children?

45. 13) Look at the phenotypes of Beyonce and Jay Z. If these two had children, could they have children with a widow’s peak? Why or why not?

46. Dihybrid Cross • Can you create a punnett square to cross these two pea plants: TtRr x ttRr *T=tall, t=short, R=round, r=wrinkled Hint: the punnett square is bigger than 4 parts

47. Vocab chart checked tomorrow Punnett square quiz Friday

48. Bell Ringer 12/5/13 • In humans, brown eyes (B) are dominant over blue (b)*. A brown-eyed man marries a blue-eyed woman and they have three children, two of whom are brown-eyed and one of whom is blue-eyed. Draw the Punnett square that illustrates this marriage. What is the man’s genotype? What are the genotypes of the children?

49. Incomplete Dominance • In this case, neither allele is completely dominant over the other, so the outcome of a cross is a 3rd phenotype that is different from either of the ones that were crossed

50. Example of incomplete dominance When curly hair is crossed with straight hair, sometimes wavy (a blend of the two) is the outcome: CC is curly (homozygous curly) cc is straight (homozygous straight) Cc is wavy (heterozygous) What is the outcome of a cross between a curly haired father and a wavy haired mother?