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Warm- Up

Warm- Up. Brown fur is dominant to white fur in a type of bunny. Draw a Punnett square to show a cross between a homozygous recessive dad and a heterozygous mom. What genotype(s) in the offspring will code for brown fur? What is the probability that their bunnies will have white fur?. Agenda.

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Warm- Up

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  1. Warm- Up Brown fur is dominant to white fur in a type of bunny. Draw a Punnett square to show a cross between a homozygous recessive dad and a heterozygous mom. • What genotype(s) in the offspring will code for brown fur? • What is the probability that their bunnies will have white fur?

  2. Agenda • Objectives: SWBAT: Analyze a dihybrid cross to determine the probability of a particular trait, given completed Punnett square • Go over and turn in homework • Notes • Stepwise Dihybrid crosses • Exit Ticket • Calendar • Quiz Thursday

  3. Friday’s Homework

  4. Steps to solving genetics problems • Identify the letter you’ll use. • Write the genotypes of the parents. • Draw the Punnett Square. • Determine the possible genotypes and phenotypes of the offspring. • Determine the probability of a given genotype or phenotype. COPY THE STEPS!

  5. Steps to solving genetics problems • Identify the letter you’ll use. (B) • Write the genotypes of the parents. (bb, Bb) • Draw the Punnett Square. • Determine the possible genotypes and phenotypes of the offspring. Bb= brown, bb= blue • Determine the probability of a given genotype or phenotype.

  6. For each Punnett Square that we’ve done, how many traits did we study?

  7. Monohybrid Crosses • Up to this point, we have only been looking at monohybrid crosses • Two parents are mated (hybrid) • We only examine one trait (mono) • Today we’re going to start looking at dihybrid crosses

  8. What is a Dihybrid Cross? • “Di” means two • In a dihybrid cross • Two parents are mated (hybrid) • We examine two traits (di) A dihybrid cross is used to determine the possible offspring of two parents based on two traits.

  9. c. In this example: • Tail length is indicated by S for short tail or s for long tail. • Coat color is indicated by B for brown coat or b for white coat while

  10. Steps to solving genetics problems • Identify the letter you’ll use. • Write the genotypes of the parents. • Draw the Punnett Square. • Determine the possible genotypes and phenotypes of the offspring. • Determine the probability of a given genotype or phenotype. COPY THE STEPS!

  11. Answer the questions in your notes section Short Tail is dominant to long tail Brown fur is dominant to white fur • What are the possible genotypes for a cat with a short tail? Use the letter “S” • What are the possible genotypes for a cat with brown fur? Use the letter “B” • What are the possible genotypes for a cat with a long tail? Use the letter “S” • What are the possible genotypes for a cat with white fur? Use the letter “B”

  12. Practice Questions 5. How many boxes show a cat with brown fur?( ____ / 16) 6. How many boxes show a cat with white fur? 7. How many boxes show a cat with a long tail? 8. How many boxes show a cat with a short tail?

  13. 9. What are the possible genotypes for a cat with a long tail and white fur? 10. What are the possible genotypes for a cat with long tail and brown fur? 11. What are the possible genotypes for a cat with a short tail and white fur? 12. What are the possible genotypes for a cat with short tail and brown fur?

  14. Practice Questions 13. How many boxes show a cat with white fur anda long tail? 14. How many boxes show a cat with brown fur and a long tail? 15. How many boxes show a cat with white fur and a short tail? 16. How many boxes show a cat with brown furand a short tail?

  15. How do we fill in a Dihybrid Cross? • http://www.dnaftb.org/5/problem.html

  16. Dihybrid practice sheet

  17. Exit Ticket • What are the possible genotypes for a yellow, wrinkled seed? • What’s the probability that a seed will be yellow and smooth?

  18. Warm Up • What is a family tree? • What’s the difference between a dihybrid cross and a monohybrid cross? • 3. What are the possible genotypes for a yellow, wrinkled seed? • 4. What’s the probability that a seed will be yellow and smooth?

  19. Agenda • Objectives: SWBAT: Identify the sex chromosomes in humans and recognize inheritance patterns that are sex-linked, using a pedigree or scenario • Notes • Human Chromosome Sheet • Pedigree Practice • Exit Ticket • Reminder • Quiz Thursday!

  20. Chromosomes • The sex chromosomes are the 23rd pair of chromosomes. • The other 22 pairs of chromosomes are called autosomes. • Traits or diseases can be either sex-linked or autosomal

  21. What are Pedigrees? • Pedigrees • chart • show how a trait is passed down over several generations • Can show autosomal or sex-linked traits b. Pedigrees look like family trees

  22. Example

  23. What are the Sex chromosomes? • The 23rd pair of chromosomes determine your sex. • There are two different sex chromosomes: X and Y • Females have the chromosomes XX • Males have the chromosomes XY • Where do we get the first X chromosome from?

  24. What are Sex-Linked Traits? a. Certain traits are called sex-linked because the traits are determined by genes on the X and Y chromosomes (the sex chromosomes). b. Most sex-linked traits are only found on the X chromosome.

  25. What are the Sex chromosomes? c. Genetic diseases or mutations are carried on the X chromosome. • Females are more likely to be carriers because they have two X chromosomes • Males are more likely to inherit genetic diseases because they only have one X chromosome • Example: Red/Green Colorblindness occurs in 1 out of 10 males in the US and 1 out of 100 females in the US.

  26. Look at Chromosome Chart

  27. Warm Up Yellow seed color (Y) is dominant to green seed color (y), and round seeds (R) are dominant to wrinkled seeds (r). A plant that is homozygous for green, wrinkled seeds is crossed with a heterozygous yellow and round plant. Draw the dihybrid cross. What’s the probability that they will produce plants with yellow, wrinkled seeds?

  28. Agenda • Objectives: SWBAT: Identify the sex chromosomes in humans and recognize inheritance patterns that are sex-linked, using a pedigree or scenario • Pedigrees • Complete Practice Sheet • White Board Practice (If there’s time) • Exit Ticket • Gather materials for Quiz

  29. Examine a Pedigree

  30. Pedigree Worksheet

  31. Put together packet • Phenotype Study • Genetics Review 1 • Reading guide 6.3 • Punnett Squares- Crosses involving one trait • Bill Nye Video Questions • Punnett Square Worksheet • Human Chromosomes • Bikini Bottom Genetics (I still have those that were turned in)

  32. Warm Up • What’s the phenotype of person #3? • What’s the genotype of person # 4? • Who are the children of person’s 1 and 2?

  33. Agenda • White Board Review • Turn in packets • Quiz • Video

  34. Draw the symbol for carrier female

  35. In bunnies, brown fur (B) is dominant to white fur (b) and short fur (S) is dominant to long fur (s). • What would be the genotype of a heterozygous brown bunny with short fur? 2. What about a homozygous white bunny with short fur?

  36. If brown fur is dominant to white fur and short fur is dominant to long fur, what’s the probability that the offspring will be brown with short fur?

  37. Write the genotype of a male with hemophilia (which is caused by a recessive gene on the X chromosome)

  38. A heterozygous tall plant is crossed with a short plant. The tall gene is dominant to the short gene in plants. What’s the probability that the offspring will be tall?

  39. What percent of the offspring are homozygous recessive?

  40. If the dominant fur color is gray and the recessive fur color is black, what’s the probability of the offspring having gray fur?

  41. In certain breeds of dogs, deafness is due to a recessive allele (d) of a particular gene, and normal hearing is due to its dominant allele (D). What percentage of the offspring of a normal heterozygous (Dd) dog and a deaf dog (dd) would be expected to have normal hearing?

  42. The following genotypes were found in a male cat and a female cat: BbSs(male) bbSS(female) Which one of the following choices is true of the phenotype of offspring from these parents? • All offspring will have black fur. • All offspring will have white fur. • All offspring will have long-haired fur. • All offspring will have short-haired fur.

  43. Hemophilia is a sex-linked recessive disease. If a woman has a genotype XRXrdoes she have hemophilia?

  44. If a man is XrY does he have hemophilia?

  45. A woman is XRXrand a man is XrY, what’s the probability that their children will have hemophilia?

  46. A man with a widow’s peak marries a woman with a straight hairline. Use the letter “H” • If one of his parents had a widow’s peak and the other did not, what is his genotype? • What’s the probability that they will have children with a widow’s peak?

  47. A pregnant couple wants to know if their child will have curly hair. Having curly hair is a dominant trait. The mother has the prettiest curls and so do her parents. The father however, has straight hair. What’s the probability that their child will have curly hair?

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