GENETICS

1. GENETICS The study of Heredity!

2. Heredity- Deals with inherited traits • Traits- Inherited characteristics • (ex. Eye color) • Our DNA determines our traits (genes) • Genetics- The study of heredity

3. Gregor Mendel • 1st person to study how traits were inherited • He found that traits were passed from a parent to the offspring by studying a garden pea • He was the 1st to succeed in predicting traits • Example: He crossed a tall pea plant with a short pea plant and found that all of the offspring were tall (TT x tt)

4. How are things inherited? • When fertilization occurs, there are 2traits given to the offspring • (1 from the mother and 1 from the father) • Each parent contributes a trait • (1 trait is called an allele) • Ex. Dad may contribute a dark hair trait and the mother a light hair trait

5. 2 kinds of traits: Dominant trait- strong trait- represented by a capital letter (ex. T) • The dominant trait will win out (show up) Recessive trait- weaker trait- represented by a lower case letter (ex. t)

6. During fertilization, alleles will randomly pair which will produce 4 different combinations called the Law of Segregation • We use the punnett square to show the 4 different possible combinations that the offspring may get

7. Solving genetics problems • Use the punnett square

8. Terms used in genetics problems: • Genotype- Shows the different gene combinations an offspring may have (example Bb) • Phenotype- The physical appearance of the offspring – ex. black hair • Homozygous allele- Both alleles are the same (ex. HH or hh) • Heterozygous allele- Both alleles are different (ex. Hh)

9. Terms contd. 5. Monohybrid cross- Cross of 1 trait (ex. Eye color) 6. Dihybrid cross- Cross of two traits (ex. eye color x hair color) We will be working with monohybrid crosses only!

11. Genetic problems—copy problems Must use punnett square and show letter of dominant/recessive • 1. A homozygous dominant man with nonattached eyebrows crosses with a woman that has attached eyebrows. • What is the phenotype? Genotype? Percent attached eyebrow? • 2. A woman that is heterozygous for dimples crosses with a man who is heterozygous for dimples. • What are the genotypes? Phenotypes? Ratio of dimples to no dimples? • 3. A man who is heterozygous for freckles crosses with a woman who lacks freckles. • What are the phenotypes? Genotypes? Percent that do not have freckles? • 4. A woman with a square face crosses with a man that is homozygous dominant for a round face. • What are the genotypes? Phenotypes? Ratio of round to square? • 5. A woman who has heterozygous almond shaped eyes crosses with a man that is homozygous dominant for almond eyes (round is recessive) • What are the phenotypes? Genotypes? Percent of almond shaped?

12. A heterozygous man with normal joints marries a woman that is recessive for double joints. • What are the genotypes? • What are the phenotypes? • What percent are double jointed?

13. Problems • 1. A woman that is heterozygous for a big mouth crosses with a man that has a small mouth • A. genotype? • B. phenotype? • C. ratio large to small

14. 2. A homozygous dominant man for cleft chin crosses with a woman that lacks a cleft chin. • A. phenotype • B. genotype • C. Percent non cleft

15. 3. A homozygous dominant bushy eye browed crosses with a woman that is heterozygous bushy eyebrowed. • A. genotypes? • B. phenotypes? • C. percent bushy?

16. drawing • 1. Go to microsoft word • Click on insert, then pictures, then autoshapes • 2. When you have finished your drawing • Save as: • Shared drive (F), click on osborn, your period, file name should be your name • Do not print!!!

17. Probability—likelihood of an event occuring • Example: probability of inheriting a disease

18. pedigree