Transcript BbRr x BbRr
HAPPY TUESDAY!!! BELL WORK (Buff Binder): Answer questions 1-7 (at your table) with your partner. You will also need your journal today. Long eyelashes (E) are dominant to short eyelashes (e). 1. What is the trait in this scenario? 2. 3. 4. 5. 6. 7. 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! 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% Set up today’s page in your journal… • Title: Dihybrid Crosses • Page: 45 • Date: 12-2-14 • Essential Question: Why can’t genetic outcomes be predicted with 100% accuracy? Dihybrid Cross: a cross that shows the possible offspring for two traits 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. 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 BR BbRr x BbRr Fur Color: B: Black b: White Coat Texture: R: Rough r: Smooth Step 3: Fill in the Punnett Square (find the possible genotypes of the offspring) BR Br bR br Br bR br 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? 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 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.