1. Chapter 11 - Genetics

2. What is Genetics? • The scientific study of heredity. • What is heredity? • The passing of traits from one generation to the next • Characteristics that are inherited from each parent • Tall or Short • Blonde or Brown Hair • Blue or Green Eyes

3. The Father of Genetics • Gregor Mendel and his peas… • Austrian Priest and teacher who tended the gardens. • Experimented with pea plants • Observed how traits are inherited, what traits were passed from parents to offspring.

4. Mendel’s experiment • Mendel crossed many different traits in pea plants and recorded his results. • He did 4 unique things in his experiment • Counted only one trait at a time • Used large numbers of data to off set chance • Did many identical experiments and combined results • Used probability to analyze results

5. Mendel’s Experiment

6. Vocabulary Assignment • Using your textbook (pgs 263- 274), define the following words. Find the definition from the chapter reading…not the glossary  Mendel Genetics Trait homozygous Hybrid heterozygous Gene phenotype Allele genotype Gamete incomplete dominance Codominance true-breeding (purebred)

7. Genes vs. Alleles A gene is a section of DNA that forms a trait (protein). For example: Hair color, Height, ear lobes…. Alleles are different forms of a gene. For example: brown hair, blonde hair or Tall and short. You get one allele for each trait from your parents…

8. How do we figure out which alleles win? • You get one allele from each of your parents in the egg and sperm. • Dominant allele – the allele that “wins”. We use a capital letter “R” • Recessive allele – the allele that is hidden or loses . We use a lower case letter “r”.

9. Let’s do an example • Lets pretend that… R = can roll their tongue r = can’t roll their tongue • RR = Dominant, Dominant - Homozygous This person can roll their tongue • Rr = Dominant, recessive – Heterozygous (hybrid) • This person can roll their tongue • rr = recessive, recessive - Homozygous • This person can’t roll their tongue

10. So the basics … • Each gamete (sperm or egg) cell has one allele for a trait. • When they fertilize, the two alleles are joined – (remember most basic traits need two alleles) • The dominant alleles will always be expressed • If there are two recessive alleles, then the recessive form of the trait will be expressed.

11. 1-Trait Punnett SquaresThey show the possible outcomes of crosses.

12. Punnett Square Vocabulary • On your Punnett Square, the letters (alleles) are called the Genotype. • Example: RR, Rr, rr • The Phenotype is what the physical trait actually looks like (words) • Example: can roll tongue, blond hair, blue eyes, etc.

13. To begin a Punnett Square 4 steps • Make a box • Put the genotypes of the parents on the outside. Example: Cross Tt x tt

14. Punnett Squares cont’d. Steps, cont’d • Fill in the box • Figure out the genotype and phenotype of the offspring. *Show as a percent or fraction Genotype - letters TT 0% Tt 50% tt 50% Phenotype - appearance 50% Can Roll tongue 50% Can’t Roll Tongue T t tt Tt Tt tt tt

15. Practice Problem #2 – Word Problem • B = Brown Hair • b = blonde hair • Cross a homozygous brown haired man with a heterozygous brown haired female. What are the genotypes and phenotypes of their possible offspring? Genotype: BB = Bb = bb = Phenotype Brown hair = blond hair =