3. Section 10.1 Summary – pages 253-262 Genetics—Branch of biology that studies heredity Genetics—Branch of biology that studies heredity Heredity – the passing on of characteristics from parents to offspring Heredity – the passing on of characteristics from parents to offspring Gregor Mendel--Austrian monk who used pea plants to study how traits are passed from one generation to the next Gregor Mendel--Austrian monk who used pea plants to study how traits are passed from one generation to the next

4. Section 10.1 Summary – pages 253-262 Traits—characteristics that are inherited Traits—characteristics that are inherited Hybrid—offspring of parents (pea plants) that have different forms of a trait Hybrid—offspring of parents (pea plants) that have different forms of a trait Ex.—tall pea plant bred with short pea plant Ex.—tall pea plant bred with short pea plant

5. Mendel bred tall pea plants with short plants Mendel bred tall pea plants with short plants The offspring in the 1 st generation were all tall The offspring in the 1 st generation were all tall The offspring in the second generation were 75% tall and 25% short 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 The short trait disappeared in the 1 st generation and reappeared in the 2 nd generation Mendel’s Experiment Cross-pollination—using pollen from one plant to pollinate a different plant Cross-pollination—using pollen from one plant to pollinate a different plant

6. Section 10.1 Summary – pages 253-262 P generation—original parents F 1 generation—offspring of the parent plants (filial) Ex.Your parents are P and you are F 1 Short pea plant Tall pea plant All tall pea plants 3 tall: 1 short P1P1P1P1 F1F1F1F1 F2F2F2F2

7. Section 10.1 Summary – pages 253-262 Alleles—Different forms of the same gene, each one located on different copies of the same chromosome (1 from mother and 1 from father) Alleles—Different forms of the same gene, each one located on different copies of the same chromosome (1 from mother and 1 from father) Ex. T is allele for tall plant, t is allele for short plant Ex. T is allele for tall plant, t is allele for short plant

8. 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

9. Section 10.1 Summary – pages 253-262 The second generation Recessivetrait Dominanttrait Seedshape Seedcolor Flowercolor Flowerposition Podcolor PodshapePlantheight round yellow purple axial (side) (side) green inflated tall tall wrinkled green white terminal(tips) yellow constricted short

10. Section 10.1 Summary – pages 253-262 Phenotype—physical appearance Ex. Phenotype is tall Genotype—genetic makeup Ex. Genotype can be TT for a tall plant Tall pea plant

11. Section 10.1 Summary – pages 253-262 Homozygous—2 same alleles for a trait Ex. TT-tall tt-short Heterozygous—2 different alleles for a trait (carrier) Ex. Tt-tall TT, Tt-tall tt-short

12. Simple Genetic Human Traits Tongue Rolling (R) Tongue Rolling (R) Dimples (D) Dimples (D) Freckles (F) Freckles (F) Eye Color: Brown is dominant to blue (B) Eye Color: Brown is dominant to blue (B) Hitchhiker’s Thumb (h) Hitchhiker’s Thumb (h)

14. 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 Law of segregation—Each gene has 2 alleles for a trait, after meiosis each gamete receives one of these alleles Law of Independent assortment – genes for different traits are independently inherited of each other Law of Independent assortment – genes for different traits are independently inherited of each other

15. Punnett square--A tool used to predict the possible offspring of a cross between 2 parents Punnett square--A tool used to predict the possible offspring of a cross between 2 parents Monohybrid cross--crossing a single trait between 2 parents Monohybrid cross--crossing a single trait between 2 parents Genotype of the parents along top and side of square Genotype of the parents along top and side of square Cross each trait individually Cross each trait individually

16. 1. Cross TT x tt 1. Cross TT x tt T T t t Tt Genotypic ratio 100% Tt Phenotypic ratio 100% tall

17. 2. Cross Tt x tt 2. Cross Tt x tt T t t t tt Tttt Genotypic ratio 50% Tt 50% tt 1 Tt : 1 tt Phenotypic ratio 50% tall 50% short 1 tall : 1 short

18. 3. Cross Tt x TT T t T T TT Tt TTTt Genotypic ratio 50% TT 50% Tt 1 TT : 1 Tt Phenotypic ratio 100% tall

19. 4. Cross Tt x Tt 4. Cross Tt x Tt T t T t TT Tt tt Genotypic ratio 25% TT 50% Tt 25%tt 1 TT : 2 Tt : 1 tt Phenotypic ratio 75% tall 25% short 3 tall : 1 short

20. Female (eggs): XX Female (eggs): XX Male (sperm): XY Male (sperm): XY Sex Chromosomes Every time a female has a baby, what percent chance do they have of having a boy? A girl? If a female has 5 boys in a row, what percent chance do they have to have another boy? A girl? Which parent determines the sex of a baby? WHY?