1. Notes: Genetics p. 46-47 Genetics is the Scientific Study of Heredity

2. What is Heredity? Heredity Offspring
The passing of traits from parents to offspring
Offspring
The product of reproduction
A new organism produced by 1 or more parents

3. Heredity Activity

4. Homework Family Tree (pg. 75) Due Wednesday 6/7/06
Survey your family and their traits
Use traits from Heredity Activity

5. Dominant Trait
Recessive Trait
Free earlobes
Attached earlobes
Hair on fingers
No hair on fingers
Widow's peak
No widow's peak
Curly hair
Straight hair
Cleft chin
Smooth chin
Smile dimples
No smile dimples

6. What is a Trait?
Trait
a genetically inherited feature of an organism (example. Eye color)
Individual factors control the traits that an offspring will have

7. What are genes? Genes The factors that control traits
The different forms of a gene are called alleles

8. Alleles
Allele
any one of a number of viable DNA codings of the same gene occupying a certain position on a chromosome
Dominant allele
Alleles that ALWAYS show up in the organism
Recessive allele
Alleles that are masked (hidden) whenever the dominant allele is present

9. Who is Gregor Mendel? Gregor Mendel “Father of Genetics”
Young European priest
Began the study of heredity and genetics using his pea plants
Through experimentation Mendel discovered that one inheritable trait would always be dominant to its recessive alternative.
Later known as Mendelian genetics

10. Mendel’s Experiment

11. Mendel’s Pea Plants Parent generation – purebred generation plants
F1 generation – 1st filial generation - hybrid offspring of purebred P generation plants
F2 generation – 2nd filial generation – hybrid offspring of the hybrid F1 generation plants

12. Mendel’s Pea Plants (continued)
Parent generation – Tall pea plant (TT) x Short pea plant (tt)
F1 generation – Tall pea plant (Tt) x Tall (Tt) pea plant
F2 generation – Tall pea plant(TT)/Tall pea plant (Tt)/ Tall pea plant (Tt)/Short pea plant (tt)

13. Some New Vocabulary
Filial - comes from the Latin word “filius” meaning son of
Purebred – pure; same traits (Ex. Tall (TT) x Short (tt))
Hybrid – mixed; different traits (Ex. Tt x (tt)

14. Example 1 B = dominant = black fur = BB or Bb
B = recessive = white fur = bb
Male BB x female bb
b b
B Bb Bb 4/4 = black fur
B Bb Bb 100% black fur

15. Example 2 B = dominant = black fur = BB or Bb
B = recessive = white fur = bb
Male Bb x female bb
b b
B Bb Bb 2/4 = ½ black fur
b bb bb 2/4 = ½ white fur
50% black fur & 50% white fur

16. Dominant or Recessive? Tt BB qq Gg Rr Ff SS

17. Genotypes and Pheotypes
Genotypes are genetic traits that are not visible
The letters (example. TT, Tt, tt)
Phenotypes are the traits that are visible; dealing with physical appearance (TT/Tt= tall and tt=short)

18. Genotype or Phenotype?
tall BB
Round eyes Gg
Brown fur
Red hair SS

19. Homozygous or Heterozygous?
Homozygous - carries two identical copies of that gene for a given trait (homo=same)
Homozygous dominant = TT
Homozygous recessive = tt
Heterozygous - carries a different version of the gene (hetero=different)
Heterozygous recessive = Tt

20. Heterozygous or Homozygous?Tt BB qq Gg Rr Ff SS