1. Inheritance of Traits

2. The Relationship Among Genes and Chromosomes

3. Genes on chromosomes carry information for physical expression of traits.

4. Genetics
Genetics: study of Heredity, or the passing of characteristics from parents to offspring.
Traits: Inherited characteristics.

5. Gregor Mendel 1822-1884 Father of Genetics Austrian monk Botanist
Mathematician
Studied traits in garden peas
Explained patterns of inheritance

6. Mendels Observations P generation = Parents white crossed with purple
F1 generation = 1st generation of offspring: All purple
F2 generation = 2nd generation of offspring: 75%purple, 25% white

7. Mendels Laws Law of Unit Factors 2 factors control each trait
Alleles- alternate forms of genes
plant height:
tall or short
flower color: white or purple

8. Allele Combinations
Homozygous (purebreed) individuals have 2 of the same allele
2 tall alleles
2 white alleles
Heterozygous (hybred) individuals have 2 different alleles
1 tall allele and 1 short allele
1 white allele and 1 purple allele

9. Mendels Laws 2. Law of dominance
Only 1 of the 2 alleles is shown in an individual
The dominant allele is always shown when it is paired with a recessive trait
The recessive allele is hidden when with a dominant allele

10. Law of Dominance
Purple: dominant
White: recessive

11. Mendels Laws Law of Segregation
Pairs of alleles separate during meiosis into gametes so that each egg or sperm has only 1 of each allele

12. Law of Segregation

13. Mendels Laws Law of Independent Assortment
Which allele ends up in which gamete is independent of other alleles and random

14. Law of Independent Asssortment

15. Tail length is independent
of fur color
(tail length and hair color have nothing to do with each other)

16. Problem Solving Using the Punnett Square
Use letter for the dominant trait
Uppercase letter for dominant
Lowercase letter for recessive
Purple: P = dominant
White: p = recessive
Tall: ____ = dominant
Short: ____ = recessive
Tall: T = dominant
Short: t = recessive

17. Problem Solving Using the Punnett Square
Phenotype- physical expression of a gene
purple, white, tall, short
Genotype- genetic makeup in letters
PP, Pp or pp, heterozygous or homozygous

18. Problem Solving Using the Punnett Square
Set up Punnett square
2 parents are crossed (given genotype or phenotype)
Possible parental gametes are determined
Possible male gametes across head of each column
Possible female gametes down head of each row

19. Punnett Square
Cross 2
Heterozygous (hybrid)
tall parents
Tt x Tt

20. Results of Punnett Square
Each square contains the possible genotype of offspring
Expressed as percent, fraction or ratio
Phenotypic results:
dominant: recessive; 3:1
¾tall, ¼ short; 75% tall, 25% short
Genotypic results:
Homozygous dominant: heterozygous:
Homozygous recessive; 1:2:1
¼ TT, ½ Tt, ¼ tt; 25%TT, 50%Tt, 25% tt

21. Round or wrinkled texture
Monohybrid Cross
One trait is observed
Yellow or green
pea color
Round or wrinkled texture

22. Dihybrid Cross Two traits are observed
Each parent donates two alleles to the offspring
Texture
Wrinkled or smooth
Color
Yellow and green