3. Intro genetics outline I.Heredity II.Traits ex. III.Gene alleles: IV.Gregor Mendel self vs. cross pollination P, F1, F2 V.Vocabulary and ex. 1. dominant 2. recessive 3. phenotype 4. genotype 5. homozygous 6. heterozygous VI.Laws VII.Punnett squares

4. Section 10.1 Summary – pages 253-262 Genetics—Branch of Biology that studies heredity Heredity—When traits are passed from one generation to the next

5. Section 10.1 Summary – pages 253-262 Traits—characteristics that are inherited and vary among individuals Ex. Hair color, height, pea color, pea shape

6. Section 10.1 Summary – pages 253-262 Gene: segment of DNA that controls a trait (ex. Height, hair color) Alleles—Different forms of a gene or trait, always have 2 alleles for each trait (one copy from mom and one copy from dad) –Ex.T is allele for tall plant, t is allele for short plant

7. Gregor Mendel--Austrian monk who used pea plants to study how traits are passed from one generation to the next “Father of genetics”

8. Section 10.1 Summary – pages 253-262 Traits Mendel studied Recessive trait Dominant trait Seed shape Seed color Flower color Flower position Pod color Pod shape Plant height round yellow purple axial (side) green inflated tall wrinkled green white terminal (tips) yellow constricted short

9. Pollination = Fertilization in plants Self pollination: male and female parts of same plant produce seeds offspring is identical to parent (purebred) Cross pollination: seeds produced from two different plants offspring have different traits than parents(hybrid)

10. Section 10.1 Summary – pages 253-262 Mendel bred tall pea plants with short plants –The offspring in the 1 st generation were all tall –The offspring in the second generation were 75% tall and 25% short –The short trait disappeared in the 1 st generation and reappeared in the 2 nd generation Mendel’s Experiment

11. Section 10.1 Summary – pages 253-262 P 1 generation—original parents F 1 generation—first filial (offspring) F 2 generation – second filial (grandkids) Short pea plant Tall pea plant All tall pea plants 3 tall: 1 short P1P1 F1F1 F2F2

12. Section 10.1 Summary – pages 253-262 Dominant—trait that covers over another trait, capital letter Ex. T (tall) is a dominant allele Recessive—trait that is covered over by another trait, lower case letter Ex. t (short) is the recessive allele T-tall t-short

13. Common dominant traits in humans--cleft chin, widow ’ s peak hairline, hair on fingers

14. Section 10.1 Summary – pages 253-262 Phenotype—physical appearance, how it looks Ex. Phenotype is tall Genotype—genetic makeup, letters Ex. Genotype can be TT or Tt Tall pea plant

15. Section 10.1 Summary – pages 253-262 Homozygous—2 same alleles for a trait (true breeding) Ex. TT, tt Heterozygous—2 different alleles for a trait, also called a hybrid Ex. Tt TT, Tt-tall tt-short

16. Practice T = tall, t = short 1.If individual is TT, what is phenotype? 2.Is TT homozygous or heterozygous? 3.If individual is Tt, what is phenotype? 4.Is Tt homozygous or heterozygous? 5.If individual is short, what is genotype?

17. Section 10.1 Summary – pages 253-262 Law of segregation—Each gene has 2 alleles for a trait, after meiosis each gamete receives one of these alleles (not both) Law of independent assortment – Genes for different trait also separate ex. Blond hair, blue eyed mom and brown hair, brown eyed dad can have kids with one of mom’s and one of dad’s traits (blond hair and brown eyes)

18. Punnett squares Used to find possible genotypes of offspring (can make predictions but not say for sure what offspring parents will have) Probability: chances of a possible outcome ex. What is the probability of tossing 4 heads in a row? ½ x ½ x ½ x ½ = 1/16

19. Practice T = tall, t = short Cross TT x tt Cross Tt x tt Cross Tt x Tt In each case, what is the probability of having tall plants?

20. Solve the previous problems following the teacher’s board demonstrations!!

21. End of Chapter 10 Show