170 likes | 252 Views
Probability of Inheritance. Mrs. Anna Ward Seventh Grade Science Ridge Road MS. DO NOW!!!!.
E N D
Probability of Inheritance Mrs. Anna Ward Seventh Grade Science Ridge Road MS
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.
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
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
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
http://www.youtube.com/watch?v=d4izVAkhMPQ REVIEW FROM FRIDAY:PUNNETT SQUARES
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?
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
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
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
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
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
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
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”
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