1. What is Genetics and Heredity?
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What is Genetics and Heredity?

2. Genetics
Genetics is the study of heredity or how traits are passed from an organism to its offspring.
Gregor Mendel is the “Father of Genetics.”
Born 1822
Died 1884

3. Mendel’s Discoveries
Mendel experimented with pea plants from
He identified different traits such as height and color.
He cross pollinated plants with opposite traits.
As a result he determined that each plant had “2 elements,” one from each parent.

4. Discoveries Continued
We now call these elements “gene”.
First Principle of Genetics—Each trait is decided by no less than one pair of genes.

5. Discoveries Continued
Second Principle of Genetics—Each trait has its own genes and one trait does not influence another trait.

6. Words We Need to Know
Allele—Each form of a gene that is possible, for example tall and short, green and yellow
Dominant Genes—Hide recessive genes, abbreviated using a capital letter, for example T for tall
Recessive Genes—Can be hidden or masked by dominant genes, abbreviated using a lower case letter, for example t for short.
Phenotype—Physical Appearance: Tall or short, green or yellow
Genotype—Combination of genes that describes a trait, TT, Tt, or tt

7. More Words
Purebred or homozygous— Organism’s genes are both the same (TT, tt)
Hybrid or heterozygous— Organism’s genes consist of two different genes (Tt)
Incomplete dominance— Neither gene is dominant or recessive example: white + red = pink

8. More Words
Sex-Linked Traits—Traits carried on the sex chromosomes (hemophilia or color-blindness)
Mutation—A change in a gene or chromosome
Probability—The possibility or likelihood that a particular event will take place
Punnett Square—Tool used to show possible combinations of genes

9. What Would Happen If….. T t T t
We crossed a pure-bred tall pea plant with a pure-bred short pea plant? T t
We crossed a pure-bred tall pea plant with a hybrid tall pea plant?

10. What Would Happen If….. T t T t
We crossed a hybrid tall pea plant with a pure-bred short pea plant? T t
We crossed 2 hybrid tall pea plants?

11. Is Genetics the only Factor?
NO!
Disease
Nutrition
Nurture or Conditioning