# probability of inheritance

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

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Mrs. Anna WardSeventh Grade ScienceRidge Road MSProbability of InheritanceIn 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.DO NOW!!!!GgggggggG=Gray fur Dominantg=white fur recessive

Gg x gg

1 Gg to 3 gg

1 gray rat to 3 gray rats

or

25 % gray75 % white

DO NOW!!! Solution GgggQuiz tomorrow to Check for Understanding

Progress Reports tomorrow at the end of class

Writing Tasks

Missing AssignmentsLast day for Late Science Fair Projects is Friday

Announcements

Short video review on Punnett Squares

Review Questions for Stickers

Calculating Ratios from Punnett SquaresIndependent Practice

Ink Think Article Genes tell old StoryAgenda

http://www.youtube.com/watch?v=d4izVAkhMPQREVIEW FROM FRIDAY:PUNNETT SQUARES

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?Review Questions for StickersWhy 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

Calculating Ratios from Punnett Squares

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 bbor 1:2:1

Calculating Ratios from Punnett SquaresBBBbBbbb

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 Blueor 3:1

Calculating Ratios from Punnett SquaresBBBbBbbb

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 RatiosBBBbBbbb

FfFfFfFfNow 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 FfPhenotype Ratio: 100 % Black FurFfffFfff

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 RabbitsIndependent PracticeSheets

Remember this from last week?

Underline or highlight things you want to remember or you deem importantCircle words you dont know? Mark thinks you dont 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 sisters bunny, Basil Q. Hoppenfluff