Slide 1 Probability and Genetics pages 88 93

Slide 1 Probability and Genetics pages 88 - 93 Principles of Probability is the Likelihood that a particular event will occur In genetics it is the likelihood a particular trait will show up in the organism/you PROBLEM: 3 out of 12 coins landed heads up. What % is this? 25% 3 X 100% = Or 1 : 4 12 1

Slide 2 Punnett Square The Punnett Square is a diagram designed by Reginald Punnett to determine the probability of an offspring having a particular genotype or a trait It is made by comparing all the possible combinations of alleles from the mother with those from thefathe r v The probability is that 4 possible offsprings can carry a particular trait shown as either……. . 1: 4 2: 4 3: 4 4: 4

Slide 3 Phenotypes and Genotypes Phenotype 1. Physical traits, those you can see Ex: Brown hair color Blonde hair color Genotype 1. Genetic (genes) makeup or allele combination inside the nucleus You can’t see your genotype 2. Represented by using letters a. Upper case = Dominant Trait MM Mm b. lower case = recessive trait mm

Slide 4 What is an Allele? A specific form of a trait in an organism Alleles come in pairs a. One from the Mother b. One from the Father Alleles are represented by letters a. Upper case letter is a Dominant Trait b. Lower case letter is a Recessive trait

Slide 5 SOLVE THIS PROBLEM Mom has blue eyes with bb genotype or allele combination B b Dad has Brown eyes with b Bb b b Bb genotype or allele combination b B b b b What is the Phenotype for each child? What are the allele combinations or genotype for each child? : 4 % are Bb or bb

Slide 6 ANSWERS for Eye colors GENOTYPE PHENOTYPE 2 Children have Bb 2 Children have Brown eyes 2: 4 50 % 2 Children have bb 2: 4 50% 2 Children have Blue eyes

Slide 7 Dominant and Recessive Traits Dominant Trait – the trait that shows up or is seen in the organism/you Recessive Trait– the trait that doesn’t show up if you have the Dominant allele for the same trait, but it can still be in your genes Remember!!! We have 2 alleles for a trait One from? . . . Your Mother ! The other from? . . . Your Father ! R = ROUND FACE/ dominant r = OVAL FACE / recessive

Slide 8 Solve these Questions! Study the Punnett Square R = ROUND FACE/ dominant r = oval face/ recessive What face shape or Phenotype does Mom have? Round Face What are the Genotypes for Mother and Father? Mom is Rr Dad is rr DAD What face shape or Phenotype does Dad have? Oval Face MOM

Slide 9 Solve these Questions Study the Punnett Square How many children have the DOMINANT Round face? 2 : 4 0 r 50 % Rr How many children have the recessive oval face? 2 : 4 or 50 % rr DAD • MOM List all the genotype (letter combinations) for the children…………. Rr Rr rr rr

Slide 10 Purple People Eaters In purple people eaters one-horn is Dominant and no horn is Recessive. H = one horn/ Dominant h = no horn/ recessive What is the genotype of each parent?

Slide 11 Purple People Eaters - cont…. What is the Phenotype of each parent? One parent is one horn One parent is no horn What is the genotype for each child? Hh Hh hh hh How many children have 1 horn (Hh) One-horn: 2: 4 or 50 % How many have no horn? (hh) No horn: 2 : 4 or 50 %

Slide 12 Describing Allele Combinations Homozygous Genotype or Ho 1. Both alleles are either: a. DOMINANT A A b. recessive a a Hint: This is the same as Purebred Heterozygous Genotype or He 1. One allele is dominant - A 2. The other allele is recessive - a 3. Result - A a genotype Hint; This is the same as Hybrid

Slide 13 Describing Allele Combinations. . cont. Answer the following Questions How many offspring are heterozygous? He or Heterozygous ………. . 2: 4 or 50% Aa Aa How many are homozygous? Ho or Homozygous ………. 2: 4 or 50% AA aa

Slide 14 Cystic Fibrosis In Cystic Fibrosis a child must have the 2 recessive alleles in order to have the disease If both parents are healthy carriers of the recessive allele for Cystic Fibrosis, but do not have the disease , what is the probability of their children inheriting Cystic Fibrosis ? Chance of being a healthy carrier? 2: 4 or 50% Chance of being healthy and not have the recessive allele is ? 1: 4 or 25% Chance of having Cystic Fibrosis? 1: 4 or 25%

Slide 15 Codominance In Codominance…………… a. The alleles for a trait are neither Dominant nor Recessive b. In this case both alleles are expressed or show up as the physical trait or Phenotype c. See Figure 11, page 93 Both black and white feathers show in the offspring

Slide 16 Review questions 1. What is the Punnett Square? Answer: A diagram that shows the probability or a chance of a trait showing up in an offspring 2. What is an allele? Answer: A specific form of a trait 3. True or False: We can see our genotype? Answer: FALSE The genotype is what our genes are for a specific trait

4. Which trait is seen in the organism? Dominant or Recessive ? Answer: The Dominant Trait if the organism has it 5. When is the only time the recessive trait or allele shows? Answer: When the organisms doesn’t have the Dominant trait or allele 6. True or False: A heterozygous or He trait has both Dominant and recessive allele. Answer: TRUE Bb for brown eyes 7. What is Codominance? Answer: When the alleles are neither dominant nor recessive. Both alleles or traits show up