1.  HAPPY Wednesday!!! 
On page 51 in your journal Answer questions 1-7 (at your table) with your partner.

2. Long eyelashes (E) are dominant to short eyelashes (e).
1. What is the trait in this scenario?
What are the two alleles in this scenario?
A woman is homozygous recessive. What is her genotype?
A man is homozygous dominant. What is his phenotype?
A man is heterozygous for eyelashes. What is his genotype.
A woman’s genotype is EE. What is her phenotype?
A cross occurs between a homozygous recessive male and a heterozygous woman….
What percent chance will their first child have long eyelashes?
What percent chance will their 8th child have long eyelashes?
HINT…DRAW A PUNNETT SQUARE!

3. Long eyelashes (E) are dominant to short eyelashes (e).
What is the trait in this scenario?
Eyelash Length

4. Long eyelashes (E) are dominant to short eyelashes (e).
What are the two alleles in this scenario?
E and e OR
Long and short eyelashes

5. Long eyelashes (E) are dominant to short eyelashes (e).
3. A woman is homozygous recessive. What is her genotype? ee

6. Long eyelashes (E) are dominant to short eyelashes (e).
A man is homozygous dominant. What is his phenotype?
Long eyelashes

7. Long eyelashes (E) are dominant to short eyelashes (e).
A man is heterozygous for eyelashes. What is his genotype? Ee

8. Long eyelashes (E) are dominant to short eyelashes (e).
A woman’s genotype is EE. What is her phenotype?
Long Eyelashes

9. Long eyelashes (E) are dominant to short eyelashes (e).
A cross occurs between a homozygous recessive male and a heterozygous woman….
Male – ee
Female - Ee

10. Long eyelashes (E) are dominant to short eyelashes (e).
7. A cross occurs between a homozygous recessive male and a heterozygous woman…. e e Ee ee E e

11. Long eyelashes (E) are dominant to short eyelashes (e).
What percent chance will their first child have long eyelashes?
What percent chance will their 8th child have long eyelashes?
50%
50%

12. Test Friday

13. No tutorials today

14. You should have turned in….
Reebop Sub Day Video Notes Note Cards Harry Potter Practice Worksheet (Friday Sub Day) Penny Lab (Monday) Alien WS (Yesterday)

15. Set up today’s page in your journal…
Title: Dihybrid Crosses
Page: 52
Date:
Essential Question: How are dihybrid crosses different from a monohybrid cross?

16. Dihybrid Cross: a cross that shows the possible offspring for two traits
Trait one
Trait Two
Coat Texture: R: Rough r: Smooth
Fur Color: B: Black b: White
In this example, we will cross a heterozygous individual with another heterozygous individual. Their genotypes will be:
BbRr x BbRr

17. Dihybrid Cross BbRr x BbRr
Step 1: Find ALL possible gametes that can be made from each parent.
Remember, each gamete must have one B and one R.
DAD
MOM

18. Foil BR Br
BbRr bR br

19. Practice
What are the possible gametes for BBrr Br

20. Practice
What are the possible gametes for HhTT? HT hT

21. F O I L BbRr x BbRr Dihybrid Cross Br bR br Possible gametes: BR DAD
MOM
F O I L

22. BbRr x BbRr Dihybrid Cross DAD MOM
Step 2: Arrange all possible gametes for dad on the top of your Punnett Square, and mom down the side

23. Dihybrid Crosses: a cross that shows the possible offspring for two traits
BbRr x BbRr BR bR br Br
Fur Color: B: Black b: White B B R R B B r R b B R R b B r R
Coat Texture: R: Rough r: Smooth B B r r b B R r B B R r b B r r
Step 3: Fill in the Punnett Square (find the possible genotypes of the offspring) B b R B b r R b b R R R b b r R B b R r B b r r b b R r b b r r

24. Dihybrid Crosses BR bR Br br BbRr x BbRr BBRR BbRR BbRr BBRr BBrr Bbrr
Fur Color: B: Black b: White
Coat Texture: R: Rough r: Smooth

25. How many of the offspring would have a black, rough coat?
How many of the offspring would have a black, smooth coat?
How many of the offspring would have a white, rough coat?
How many of the offspring would have a white, smooth coat? BR bR br Br
BBRR
BbRR
BbRr
BBRr
BBrr
Bbrr
bbRR
bbRr
bbrr
Fur Color: B: Black b: White
Coat Texture: R: Rough r: Smooth

26. How many of the offspring would have black, rough coat?
How many of the offspring would have a black, smooth coat?
How many of the offspring would have a white, rough coat?
How many of the offspring would have a white, smooth coat? BR bR br Br
BBRR
BbRR
BbRr
BBRr
BBrr
Bbrr
bbRR
bbRr
bbrr
Phenotypic Ratio=
9:3:3:1
Fur Color: B: Black b: White
Coat Texture: R: Rough r: Smooth

27. Answer the following question at the bottom of your notes: What type of scientist might use a dihybrid cross?

28. Practice in your notes…
In pea plants, yellow seeds (Y) are dominant over green seeds (y), and rounded peas (R) are dominant over wrinkled peas (r). Cross (what do you have to draw?) a plant that is heterozygous for both traits with a plant that is homozygous recessive for both traits. Draw a Punnett square to show all possible offspring, and determine the genotypic and phenotypic ratios.

29. YyRr X yyrr YR yR yr Yr
YyRr
yyRr
yyrr
Yyrr

30. More Practice
Work on the SpongeBob Dihybrid Cross worksheet. Turn it in at the end of class.

31. Fractions Method BbRr x BbRr Bb Bb Rr Rr
Step 1: Split the traits for mom and dad
MOM
DAD
BbRr x BbRr Bb Bb Rr Rr

32. Step 2: Create 2 punnett squares. Same letters together!
DAD
DAD B b R r B BB Bb R RR Rr b Bb bb r Rr rr
MOM
MOM
Step 3: Fill in the punnett squares

33. Step 4: Solve problems by multiplying fractions
DAD
DAD
Fur Color: B: Black b: White B b R r B BB Bb R RR Rr
Coat Texture: R: Rough r: Smooth b Bb bb rr r Rr
MOM
MOM
How many of the offspring would have a black, smooth coat? 3 1 3 X = 4 4 16

34. Step 4: Solve problems by multiplying fractions
DAD
DAD
Fur Color: B: Black b: White B b R r B BB Bb R RR Rr
Coat Texture: R: Rough r: Smooth b Bb bb rr r Rr
MOM
MOM
How many of the offspring would have a white, rough coat? 1 3 3 X = 4 4 16

35. Step 4: Solve problems by multiplying fractions
DAD
DAD
Fur Color: B: Black b: White B b R r B BB Bb R RR Rr
Coat Texture: R: Rough r: Smooth b Bb bb rr r Rr
MOM
MOM
How many of the offspring would have a white, smooth coat? 1 1 1 X = 4 4 16

36. Practice in your notes…
In pea plants, yellow seeds (Y) are dominant over green seeds (y), and rounded peas (R) are dominant over wrinkled peas (r).
Cross a plant that is heterozygous for both traits with a plant that is homozygous recessive for both traits.
Genotypes:
YyRr and yyrr
What is the probability that the plant will be yellow and wrinkled?

37. Y y R r y Yy yy r Rr rr y Yy yy Rr rr r 2 2 4 X = 4 4 16
How many of the offspring would have a yellow, wrinkled seed? 2 2 4 X = 4 4 16