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Probability of Inheritance

Probability of Inheritance. Mrs. Anna Ward Seventh Grade Science Ridge Road MS. DO NOW!!!!.

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Probability of Inheritance

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  1. Probability of Inheritance Mrs. Anna Ward Seventh Grade Science Ridge Road MS

  2. DO NOW!!!! In rats, gray fur (G) is dominant over white fur(g). Complete a Punnett Square to identify the possible fur colors of offspring between a rat that is heterozygous for gray fur (Gg) with a rat that is homozygous recessive (gg) for white fur. In addition, identify the ratios of gray fur to white fur.

  3. G=Gray fur Dominantg=white fur recessiveGg x gg1 Gg to 3 gg1 gray rat to 3 gray ratsor 25 % gray75 % white DO NOW!!! Solution G g g g

  4. Quiz tomorrow to Check for Understanding • Progress Reports tomorrow at the end of class • Writing Tasks • Missing Assignments—Last day for Late Science Fair Projects is Friday Announcements

  5. Short video review on Punnett Squares • Review Questions for Stickers • Calculating Ratios from Punnett Squares • Independent Practice • Ink Think Article “Genes tell old Story” Agenda

  6. http://www.youtube.com/watch?v=d4izVAkhMPQ REVIEW FROM FRIDAY:PUNNETT SQUARES

  7. Review Questions for Stickers In humans, brown eyes (B) are dominant to blue eyes (b). • What are the possible phenotypes for eye color as listed above? • What would the be genotype of: • a homozygous dominant human? • A homozygous recessive human? • A heterozygous human? • Which genotype(s) would code for brown eyes? • Which genotype(s) would code for blue eyes? • Draw a Punnett Square that crosses a homozygous dominant woman (BB) with a heterozygous man (Bb). What are the possible genotypes and phenotypes? • Draw a Punnett Square that crosses a heterozygous female (Bb) with a homozygous recessive male (bb). What are the possible genotypes and phenotypes?

  8. Why do we use Punnett Squares? • What does the term PUREBRED mean? • Where have you heard this term before? • Would PUREBRED BE HETEROZYGOUS or HOMOZYGOUS? • What does the term HYBRID mean? • Would HYBRID be HETEROZYGOUS or HOMOZYGOUS? • Any other questions from the video? Class Discussion

  9. Calculating Ratios from Punnett Squares

  10. For Monohybrid Crosses, the ratios are always going to occur in fourths, because there are four squares. • To Calculate the GENOTYPIC RATIOS, count the number of each GENOTYPE and put that over 4. • Example: The Genotypic Ratio in the figure to the right is: 1 BB to 2 Bb to 1 bb or 1:2:1 Calculating Ratios from Punnett Squares

  11. To Calculate the PHENOTYPIC RATIOS, count the number of each PHENOTYPE and put that over 4. • There are typically only two phenotypes for monohybrid crosses, the dominant & the recessive trait. • Example: The Phenotypic Ratio in the figure to the right is: 3 Brown to 1 Blue or 3:1 Calculating Ratios from Punnett Squares

  12. This is something you should be very familiar with from MATH class. • For monohybrid crosses, it is always going to be a factor of 25%, because there are 4 squares. • You can calculate the percentages based on the phenotype or genotype. • Example: • The genotype is 25% BB, 50% Bb, and 25% bb. • The phenotype is 75% brown, 25% blue. Calculating Percentages from Ratios

  13. Now you try! Question # 1 In Rabbits, Black Fur (F) is dominant to White Fur (f). Imagine you have a Homozygous Dominant Black Male Rabbit that you are going to mate with a Homozygous (FF) Recessive White Female Rabbit (ff). Draw the Punnett Square to predict the offspring. What is the genotype ratio? What is the phenotype ratio? Genotype Ratio: 100 % Heterozygous or Ff Phenotype Ratio: 100 % Black Fur

  14. Now you try! Question # 2 In Rabbits, Black Fur (F) is dominant to White Fur (f). Imagine you have a Heterozygous Black Male Rabbit (Ff) that you are going to mate with a Homozygous Recessive White Female Rabbit (ff). Draw the Punnett Square to predict the offspring. What is the genotype ratio? What is the phenotype ratio? Genotype Ratio: 50% Heterozygous (Ff) Rabbits to 50% Homozygous Recessive Rabbits (ff) Phenotype Ratio: 50% Black Rabbits, 50% White Rabbits

  15. Independent PracticeSheets

  16. Remember this from last week? • Underline or highlight things you want to remember or you deem important • Circle words you don’t know • ? Mark thinks you don’t understand • Attach the Passage in your Science Notebook. INK THINK:“Old Genes Tell the Story”

  17. In Rabbits, Black Fur (F) is dominant to White Fur (f). Imagine you have a Heterozygous Black Male Rabbit that you are going to mate with a Heterozygous Black Female Rabbit. • Draw the Punnett Square to predict the offspring. • What is the genotype ratio? • What is the phenotype ratio? EXIT TICKET OUT THE DOOR My sister’s bunny, Basil Q. Hoppenfluff

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