Genetics 101: Heredity & Probability Essential questions: EQ: What makes me the way I am? EQ: What are the chances that certain traits will be passed on to future generations?

Scenario #1: In humans, tongue rolling (T) is dominant. A man that can roll his tongue (TT) is married to a woman who cannot (tt). Will any of their children be able to roll their tongue? Support your answer.

Punnett Squares: tool to help predict the possible genotypes of the offspring.** t T T T T No tongue roller (tt) Tongue roller (TT) Monohybrid cross P 1 generation F 1 generation Male gametes Female gametes What are the genotypic and phenotypic ratios?

Mendel’s Rule of Dominance: When parents are homozygous for contrasting traits, all the offspring will express the dominant trait. Mendel called the expressed trait DOMINANT. The trait that disappeared was RECESSIVE. For examples of dominant traits in pees See pg. 264

Dominant Traits in Humans Rule of Dominance rules!

Scenario #2: One of the boys from the previous case study grows up and marries a woman who can also roll her tongue. They have a child, however who cannot. What are the genotypes of the mother, father, and children? What are the couples chances of having a child that can roll his tongue?

Can you figure out the Genotype of the parents and other possible genotypes? t Tongue roller (___) Monohybrid cross F 1 generation F 2 generation Male gametes Female gametes

Mendel’s First Law Law of Segregation: allele pairs separate or “segregate” during gamete formation, and randomly unite at fertilization.

Scenario #3: The Dreaded Dihybrid Cross A man (RRFF) can roll his tongue and has freckles. He marries a woman who cannot roll her tongue and has no freckles. (rrff) What will the genotype of their offspring look like?  P 1 = RRFF x rrff = RrFf (F 1 )  All freckled, tongue rollers. When crossing for more than one contrasting trait, the rule of dominance is still RULES.

Scenario #4 A man heterozygous for tongue rolling and freckles (RrFf) marries a woman who is also heterozygous for tongue rolling and freckles. What are their chances of having children who…  Have freckles and can roll their tongue?  Have freckles but can’t roll their tongue?  Who does not have freckles but can roll their tongue?  Who does not have freckles and can’t roll their tongue?

F 1 cross: RrFf x RrFf (Hint: Determine the number of possible gametes 1 st )

Mendel’s Second Law: Law of Independent Assortment: Genes for different traits segregate and are inherited independently of each other.  Ex: Tongue Roller and Freckles More practice with punnett squares

Examples of Mendel’s Work: What are the Genotypic and Phenotypic Ratios? More practice with punnett squares

Incomplete dominance: A cross between organisms with different phenotypes that produces offspring with a third phenotype. (often a blending of the two phenotypes) Red (RR) x White (WW) Pink (RW)

Codominance: Heterozygous genotype results in a phenotypic expression of both dominant alleles. X= Black (BB)Speckled (BW)White (WW)

Multiple Alleles: Traits controlled by more than two alleles within a population. Ex: Blood Types (ABO)

Polygenic Inheritance: Inheritance pattern of a trait is controlled by two or more genes. Examples:  Skin color  Eye Color  Height More practice with punnett squares

Lincoln writes Emancipation Proclamation 1950 Korean war begins 1964 Beatles on TV 1865 Mendel discovers rules of inheritance 1910 Scientists determine that genes reside on the chromosomes Alfred Hershey and Martha Chase show that DNA is the genetic material Watson, Crick, Wilkins, and Franklin determine the structure of DNA Human Genome project begins 2003 Human Genome project is complete. History and Genetics Timeline