1. Probability and Inheritance

2. ►T►T►T►The likelihood that a particular event will occur. Probability

3. Percentages  One way you can express a probability is as a percentage.  Suppose that 3 out of 5 tossed coins landed with heads up. Here’s how you can calculate what percent of the coins landed with heads up: 1.Write the comparison as a fraction. Specific events vs possible events 3 out of 5 = 3/5 2. Multiply the fraction by 100% to express it as a percentage. 3/5 x 100%/1 = 60%

4. How is probability associated with genetics? ►M►M►M►Much like the flipping of a quarter, the likelihood of alleles is completely random.

5. What is a PUNNETT SQUARE ? ► predict the probability ► A tool to predict the probability of certain traits in offspring that shows the different ways alleles can combine ► phenotype genotype ► A way to show phenotype (the trait) & genotype (the alleles) ► ► A chart that shows all the possible combinations of alleles that can result when genes are crossed

6. Genotype and Phenotype ► Genotype refers to genetic makeup, or what alleles the organism has ► Phenotype refers to the physical appearance of an organism  Organisms with the same phenotype may not have the same genotype

7. Dominant and Recessive Traits ► When making Punnett squares, capital letters are used to represent dominant traits  P= Purple Flower   always shows up when present ► Lower case letters are used to represent recessive traits  p= white flower   hidden when dominant allele is present

8. Homozygous & Heterozygous ► Organisms that have two identical alleles for a particular trait (TT or tt) are said to be homozygous homozygous  True-breeding ► Organisms that have two different alleles for the same trait Tt are heterozygous  Hybrid

9. A Punnett Square In this cross, both parents are heterozygous for the trait of seed shape. R represents the dominant round allele, and r represents the recessive wrinkled allele.

10. Punnett Square #1: breeding 2 homozygous animals Bb BB b b Phenotype 100% All brown offspring Brown= BB white= bb Daddy Mommy What is the probability? Genotype 100% Bb = hybrid brown

11. Punnett Square #2: breeding 1 homozygous animal and 1 heterozygous animal Bbbb Bbbb Bb b b Phenotype 50% brown offspring 50% white offspring Brown= Bb white= bb Daddy Mommy What is the probability? Genotype 50% Bb = hybrid brown 50% bb= white

12. Punnett Square #3: breeding 2 heterozygous animals BBBb bb Bb B b Phenotype 75% brown offspring 25% white offspring Brown= Bb Daddy Mommy What is the probability? Genotype 25% BB= brown 50% Bb = hybrid brown 25% bb= white

13. Codominance In codominance, the alleles are neither dominant nor recessive. As a result, both alleles are expressed in the offspring.

14. Incomplete Dominance When one allele is NOT completely over another (they blend) When one allele is NOT completely dominant over another (they blend) ► Example: In carnations the color red (R) is incompletely dominant over white (W). The hybrid color is pink.