1. Genetics

2. What is Genetics? The study of heredity
Heredity: passing of traits from parent to offspring

3. Study of Genetics Children inherit traits
Need to study many generations

4. Genes Section of DNA on chromosomes
Carry instructions to make living things
Paired: 1 from mom
& 1 from dad

5. Gregor Mendel (1857) “Father of Genetics”
Discovered patterns of inheritance by breeding pea plants

6. Flower Anatomy

7. What We Know Different forms of a gene are alleles
Represented by letters
Ex. flower color alleles
P (purple) or p (white)

8. Alleles Capital letter = dominant allele Ex. P (purple)
Lower case = recessive allele
Ex. p (white)

9. Important Vocabulary
Genotype = alleles (letters) that make up that trait
Ex. PP
Phenotype = physical appearance of trait
Ex. Purple

10. Important Vocabulary (Cont.)
Homozygous: two of the same alleles
Ex. PP or pp
Heterozygous: two different alleles (Aka Hybrid)
Ex. Pp

11. Inheritance Of Traits
If you inherit one dominant allele the recessive allele will not be expressed

12. Predicting Our Traits
Punnett squares show possible genotypes

13. Setting up a Punnett Square
Alleles from Father g
Alleles from Mother g
G = Green g = White

14. Interpreting Punnett SquaresGg
Offspring

15. Interpreting Punnett Squares (Cont.)
Offspring are:
100 % Heterozygous
Their genotypes are Gg
Their phenotype are green

19. Probability Measure of how likely something will occur
Ex. What is the probability of getting heads when you flip a coin?
Ans. 50%

20. Probability (cont.)
What is the probability of flipping a coin and getting heads 3 times in a row?
½ x ½ x ½ = 1/8

21. Incomplete Dominance Dominant & recessive traits appear to "blend"
Ex. snapdragon flowers
red x white = pink
RR rr Rr

22. Codominance Two traits are both fully seen
Ex. Roan Horses have both red & white hairs

23. Codominance
Black (B) White (W)
BB = Black
WW = White
BW = Spotted

24. Multiple Alleles Two or more alleles control the phenotype
Ex. Human ABO blood groups

27. Polygenic Traits Traits that are controlled by multiple genes
Ex. height, weight, hair color, skin color

28. Sex-Linked Traits Carried on sex chromosomes
Most are recessive & on X chromosome
Color blindness, hemophilia

29. Sex-Linked Traits (cont.)
Affect men more than women
Men have only one X chromosome
Women can be carriers or affected