1. Gregor Mendel -Breeded purple and white flowered pea plants and observed the flower color. -Noticed the 3:1 ratio of purple flowers to white flowers http://philosophyofscienceportal.blogspot.co m/2010/06/gregor-mendel-and-pea- breeding.html “Hmmm… why is this happening?!” 

2. Terms to Know! (These will be Helpful!) A. Alleles: The alternative versions of a gene. A potential characteristic for an organism. 1. Example: In pea plants, the plant’s flower can either be white or purple. White and purple are the alleles. B. Dominant Allele: The allele that determines the organism’s appearance. (Always written in capitalized italic letters. Ex: AA ) C. Recessive Allele: The allele that does not have noticeable effect on an organism’s appearance. (Always written in lowercase italic letters. Ex: aa )

3. More Terms that will help you A LOT… D. Law of Segregation: An egg and sperm only carry one allele each for inherited character because the two members of an allele pair separate from each other during the production of gametes. E. Homozygous: An organism that has two identical alleles for a gene. (Hint: Homo=Same) F. Heterozygous: An organism that has two different alleles for a gene. (Hint: Hetero=Different) G. Phenotype: An organism’s physical traits. Ex: purple flowers vs. white flowers H. Genotype: An organism’s genetic makeup Ex: Pp, pp, or PP (This will make more sense after the next slide!!)

4. Punnett Square: A diagram used in the study of inheritance to show the results of random fertilization For example: In pea plants, purple flowers are the dominant allele (G), and white flowers are the recessive allele (g). This is the cross of one heterozygous and one heterozygous parent. http://www.hobart.k12.in.us/jkousen/Biology/psquprac.htm In this case, each parent’s genotype is Gg. It’s offspring’s genotype will either be GG, Gg, or gg. The offspring has a 3:1 chance of being purple, because purple is the donimant allele. What color is each parent plant? PURPLE! Purple is each parent’s phenotype

5. Two Kinds of Crosses: 1.Monohybrid Cross: The crossing of organisms which only differ by one characteristic. Ex: Breeding pea plants with white and purple flower color. The only different characteristic between the two is their color. 2.Dihybrid Cross: The crossing of organisms that only differ by two characteristics. Example: pea seeds differ in both color and shape. They can be either yellow or green, and round or wrinkled.

6. Punnett Squares: Monohybrid Cross: http://slohs.slcusd.org/pages/teachers/rhamle y/Biology/Genetics/monocross.html Dihybrid Cross: Refer to picture in book on page 150.

7. Probability -All genetic crosses obey the rules of probability. These are the same rules that would apply to a coin toss, rolling dice, or drawing a card. -All genetic crosses abide by the rule of multiplication.

8. Rule of multiplication: The probability that a dual even is the product of the separate probabilities of the independent events. For example: The probability of flipping two coins and both landing on heads. -Probability of Coin 1 being heads: ½ -Probability of Coin 2 being heads: ½ -Probability of both coins being heads: ¼ -We get this because… ½ x ½ = ¼ (See page 152 for reference)

9. Any Questions? Now we get to fill in some punnett squares!!