Genetics Worksheet: Monohybrid & Dihybrid Crosses

 HAPPY Wednesday!!!  On page 51 in your journal Answer questions 1-7 (at your table) with your partner. Long eyelashes (E) are dominant to short eyelashes (e). 1. What is the trait in this scenario? 2. 3. 4. 5. 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. 6. A woman’s genotype is EE. What is her phenotype? 7. 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! Long eyelashes (E) are dominant to short eyelashes (e). 1. What is the trait in this scenario? Eyelash Length Long eyelashes (E) are dominant to short eyelashes (e). 2. What are the two alleles in this scenario? E and e OR Long and short eyelashes Long eyelashes (E) are dominant to short eyelashes (e). 3. A woman is homozygous recessive. What is her genotype? ee Long eyelashes (E) are dominant to short eyelashes (e). 4. A man is homozygous dominant. What is his phenotype? Long eyelashes Long eyelashes (E) are dominant to short eyelashes (e). 5. A man is heterozygous for eyelashes. What is his genotype? Ee Long eyelashes (E) are dominant to short eyelashes (e). 6. A woman’s genotype is EE. What is her phenotype? Long Eyelashes Long eyelashes (E) are dominant to short eyelashes (e). 7. A cross occurs between a homozygous recessive male and a heterozygous woman…. • Male – ee • Female - Ee Long eyelashes (E) are dominant to short eyelashes (e). 7. A cross occurs between a homozygous recessive male and a heterozygous woman…. e e E Ee Ee e ee ee Long eyelashes (E) are dominant to short eyelashes (e). – What percent chance will their first child have long eyelashes? 50% – What percent chance will their 8th child have long eyelashes? 50% Test Friday No tutorials today 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) Set up today’s page in your journal… • Title: Dihybrid Crosses • Page: 52 • Date: 12-2-15 • Essential Question: How are dihybrid crosses different from a monohybrid cross? Dihybrid Cross: a cross that shows the possible offspring for two traits Trait Two Trait one Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth In this example, we will cross a heterozygous individual with another heterozygous individual. Their genotypes will be: BbRr x BbRr Dihybrid Cross BbRr x BbRr DAD MOM Step 1: Find ALL possible gametes that can be made from each parent. Remember, each gamete must have one B and one R. Foil BR Br BbRr bR br Practice What are the possible gametes for BBrr Br Br Br Br Practice What are the possible gametes for HhTT? HT HT hT hT Dihybrid Cross BbRr x BbRr DAD MOM Possible gametes: BR Br bR br FOIL Dihybrid Cross BbRr x BbRr DAD MOM Step 2: Arrange all possible gametes for dad on the top of your Punnett Square, and mom down the side Dihybrid Crosses: a cross that shows the possible offspring for two traits BbRr x BbRr BR Fur Color: B: Black BB R R BR b: White Coat Texture: R: Rough Br B B R r r: Smooth Step 3: Fill in the Bb RR bR Punnett Square (find the possible genotypes of the Bb R r br offspring) br Br bR BB r R bB RR bB r R BB r r bB R r bB r r Bb r R bb R R b b rR Bb r r bb R r bb r r Dihybrid Crosses BR Br bR br BR BBRR BBRr BbRR BbRr Br BBRr BBrr BbRr Bbrr bR BbRR BbRr bbRR bbRr br BbRr Bbrr bbRr bbrr BbRr x BbRr Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth 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 BR BBRR BBRr BbRR BbRr Br BBRr BBrr BbRr Bbrr bR BbRR BbRr bbRR bbRr br BbRr Bbrr bbRr bbrr Fur Color: Coat Texture: B: Black R: Rough b: White r: Smooth 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? BR Br bR br BR BBRR BBRr BbRR BbRr Br BBRr BBrr BbRr Bbrr bR BbRR BbRr bbRR bbRr br BbRr Bbrr bbRr bbrr How many of the offspring would have a white, smooth coat? Phenotypic Ratio= 9:3:3:1 Fur Color: Coat Texture: B: Black R: Rough b: White r: Smooth Answer the following question at the bottom of your notes: What type of scientist might use a dihybrid cross? 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. YyRr X yyrr YR Yr yR yr yr YyRr Yyrr yyRr yyrr yr YyRr Yyrr yyRr yyrr yr YyRr Yyrr yyRr yyrr yr YyRr Yyrr yyRr yyrr More Practice • Work on the SpongeBob Dihybrid Cross worksheet. Turn it in at the end of class. Fractions Method Step 1: Split the traits for mom and dad DAD MOM BbRr x BbRr Bb Rr Bb Rr Step 2: Create 2 punnett squares. Same letters together! DAD DAD B b B BB Bb b bb MOM Bb R R RR r Rr r Rr rr MOM Step 3: Fill in the punnett squares Step 4: Solve problems by multiplying fractions DAD B DAD b r Rr Rr rr B BB Bb R R RR b Bb bb r MOM Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth MOM How many of the offspring would have a black, smooth coat? 3 4 X 1 4 = 3 16 Step 4: Solve problems by multiplying fractions DAD B DAD b r Rr Rr rr B BB Bb R R RR b Bb bb r MOM Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth MOM How many of the offspring would have a white, rough coat? 1 4 X 3 4 = 3 1 6 Step 4: Solve problems by multiplying fractions DAD B DAD b r Rr Rr rr B BB Bb R R RR b Bb bb r MOM Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth MOM How many of the offspring would have a white, smooth coat? 1 4 X 1 4 = 1 16 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? Y y Yy yy y Yy yy y r R Rr r rr r Rr rr How many of the offspring would have a yellow, wrinkled seed? 2 4 X 2 4 = 4 16

Genetics Worksheet: Monohybrid & Dihybrid Crosses

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