Probability of inheritance lesson 3
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Probability of Inheritance Lesson 3. Mrs. Anna Ward Seventh Grade Science James Martin MS. DO NOW!!!!.

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Probability of Inheritance Lesson 3

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Probability of inheritance lesson 3

Probability of InheritanceLesson 3

Mrs. Anna Ward

Seventh Grade Science

James Martin MS


Probability of inheritance lesson 3

DO NOW!!!!

In rats, gray fur is dominant over white fur. Complete a Monohybrid Cross 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 addtion, give the ratios of gray fur to white fur.


Probability of inheritance lesson 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


Announcements

  • Quiz today to check for understanding

Announcements


Agenda

  • Short video review on Punnett Squares

  • Quiz

  • Calculating Ratios from Punnett Squares

    • Independent Practice

  • Ink Think Article “Genes tell old Story”

Agenda


Review from yesterday punnett squares

  • http://www.youtube.com/watch?v=d4izVAkhMPQ

REVIEW FROM YESTERDAY:PUNNETT SQUARES


Probability of inheritance lesson 3

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 with a heterozygous man.

  • What are the possible genotypes?

  • Draw a Punnett Square that crosses a heterozygous female with a homozygous recessive male.

  • What are the possible genotypes?

Quiz


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 bb

    or 1:2:1

Calculating Ratios from Punnett Squares


Calculating ratios from punnett squares1

  • 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


Calculating percentages from ratios

  • 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


N ow you try

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 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


Now you try

Now you try!

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


Independent practice sheets

Independent PracticeSheets


Ink think old genes tell the story

  • 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”


Exit ticket out the door

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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