Mrs. Anna Ward Seventh Grade Science James Martin MS

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 Thank you for finding your new assigned seats quickly and quietly.  I will be returning Argumentative Writing Essays today in class. Looking Forward:  Quiz Tomorrow  Gummi Bear Lab tomorrow—pre- lab sheet  March Notebook Check next week

 Short review of Punnett Squares  Calculating Ratios from Punnett Squares  Independent Practice  Ink Think Article “Genes tell old Story”

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 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?

 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 BBBb

 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 BBBb

 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. BBBb

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 Recessive White Female Rabbit. Draw the Punnett Square to predict the offspring. What is the genotype ratio? What is the phenotype ratio? Genotype Ratio: 100 % Heterozygous or Bb Phenotype Ratio: 100 % Black Fur

Bbbb Bbbb Question # 2 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 Homozygous Recessive White Female Rabbit. Draw the Punnett Square to predict the offspring. What is the genotype ratio? What is the phenotype ratio? Genotype Ratio: 50% Heterozygous (Bb) Rabbits to 50% Homozygous Recessive Rabbits (bb) Phenotype Ratio: 50% Black Rabbits, 50% White Rabbits

 Please write the answers in your science notebook.  The handouts are class copies and should be returned on the observation deck by the end of class.  Stay in your seats. When you are done, please raise your hand.

Ink Think:  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.  Raise your hand when you are done.

Tomorrow you will be completing a VERY fun candy lab. However, you will only be allowed to participate if you bring in your completed Pre-Lab Sheet for Homework. An alternative activity will be provided.

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. 1.Draw the Punnett Square to predict the offspring. 2.What is the genotype ratio? 3.What is the phenotype ratio? My sister’s bunny, Basil Q. Hoppenfluff