6.5 Traits and Probability Set up Cornell Notes on pg. 75 Topic: 6.5 Traits and Probability Essential Questions: NONE 2.1 Atoms, Ions, and Molecules 6.5 Traits and Probability KEY CONCEPT The inheritance of traits follows the rules of probability.

6.5 Traits and Probability KEY CONCEPT The inheritance of traits follows the rules of probability.

6.5 Traits and Probability Punnett squares illustrate genetic crosses. The Punnett square is a grid system for predicting all possible genotypes resulting from a cross. –The axes represent the possible gametes of each parent. –The boxes show the possible genotypes of the offspring.

6.5 Traits and Probability A monohybrid cross involves one trait. Monohybrid crosses examine the inheritance of only one specific trait. Ex: color of flower

Punnett Squares A green pea plant (GG) is crossed with a yellow pea plant (gg) G G g g G g gg g G GG Geno type= Gg Pheno type= 100% Green

1.A purple flowered plant (Pp) is crossed with a white flowered plant (pp). What are the genotype and phenotype of the offspring? 2.A long tailed cat (TT) is crossed with a short tailed cat (tt). What are the genotype and phenotype of the offspring? Is it possible to have short tailed offspring?

P p p p Pp pp Pp G: Pp, pp P: 50% purple 50% white TT t t Tt G: Tt P: 100% long tail NO!!!!

6.5 Traits and Probability A testcross is a cross between an organism with an unknown genotype and an organism with the recessive phenotype. bb BB or Bb

Sponge Bob Genetics: Monohybrid Crosses (In Pairs)

Set up Cornell Notes on pg. 77 Topic: 6.5 Traits and Probability Essential Questions: 1.How did Mendel’s dihybrid crosses help him develop his “Law of Independent Assortment”? 2.1 Atoms, Ions, and Molecules 1.How did Mendel’s dihybrid crosses help him develop his “Law of Independent Assortment”? 6.5 Traits and Probability Please turn in your Punnett square practice worksheet from Friday.

6.5 Traits and Probability A dihybrid cross involves two traits. Ex: color of peas & shape of peas

6.5 Traits and Probability A dihybrid cross involves two traits. Y=Yellow Pea y= Green Pea R= Round Pea r= Wrinkled Pea YyRr YR Yr yR yr

6.5 Traits and Probability YY, Yy=Yellow Pea yy= Green Pea RR, Rr = Round Pea rr= Wrinkled Pea

6.5 Traits and Probability Can use ratio when determining phenotype Write the # biggest to smallest 9:3:3:1 9: Yellow smooth 3: Yellow wrinkled 3: Green smooth 1: Green wrinkled Will follow Dominance patterns Please figure out the ratio.

6.5 Traits and Probability Investigation (Pg. 76 in Notebook) In Pairs complete the “Allele Combinations and Punnett Squares” Investigation on pg. 188 in the textbook –Read the background information –Set up and fill out your dihybrid cross (Rrtt x RrTT) –Answer the 4 questions

Genotype: Ratio: RR or Rr= purple kernels rr= yellow kernels TT or T t = Smooth kernels tt = wrinkled kernels

RRT t R t R t r t r t RTRTrTrTRTRTrTrT Genotype: Ratio:

RRTt RrTt RRTt RrTt rrTt RrTt rrTt Rt Rt rt rt RTRTrTrTRTRTrTrT

1. List the genotypes and phenotypes produced by this cross: Genotypes: RrTt, RRTt, rrTt Phenotypes: Purple smooth, yellow smooth 2. What is the genotypic ratio resulting from this cross? The phenotypic ratio? Genotypic: 8RrTt:4RRTt:4rrTt = (reduce) 2:1:1 Phenoypic: 12:4 purple-smooth to yellow-smooth = 3:1 3. If the genotypes for kernel texture of two plants are tt and tt, what is the probability of their having offspring that have smooth kernels? Why? Zero; neither parent plant has a dominant allele (T). 4. Suppose that corn plant C has a known genotype of RRTT. Could corn plants with cobs that had some yellow and wrinkled kernels be produced by crossing Plant C with a plant with a genotype of your choice? Why or why not? No. All alleles are dominant, therefore no cross could lead to a recessive phenotype.

These findings led to Mendel’s second law: The Law of Independent Assortment states that allele pairs separate independently of each other during meiosis. Different traits are inherited separately Ex: Hair color is inherited independently from eye color Pea color is inherited independently from pea shape Hair line inherited independently from earlobes

6.5 Traits and Probability Gregor Mendel: Great Minds (5m20s-10m54s) The LAW OF INDEPENDENT ASSORTMENT

Sponge Bob Genetics: Dihybrid Cross

4. SpongeBob’s aunt, who is a roundpants (ss), has a cute stubby nose (ll). She has finally found the sponge of her dreams and is ready to settle down. Her fiancé always comments on how adorable her nose is (he says it reminds him of his mother’s – aww, how sweet!). They wonder what the chances are of that trait being passed on. Her fiancé is a purebred squarepants (SS) and is a hybrid for his long nose (Ll). A. Identify the genotypes of the aunt and her fiancé. Aunt = Roundpants, Stubby Nose = Fiancé = Purebred Squarepants, Long Nose = B. What are the possible gamete combinations for each person? Aunt = Fiancé = C. What are the possible genotypes for their children?

6.5 Traits and Probability Probability is the likelihood that something will happen. –predicts an average number of occurrences, not an exact number of occurrences. Probability = number of ways a specific event can occur number of total possible outcomes.

6.5 Traits and Probability Red: Female (XX) White: Male (XY) Heads: DOMINANT Tails: recessive For determining Sex: Use the Male (white) poker chip H: X T: Y Genetics with a Smile

6.5 Traits and Probability