1. Category 4 – STAAR Review
GENETICS REVIEW
Category 4 – STAAR Review

2. Genetics and Heredity Genetics: The study of heredity.
Gregor Mendel: Father of genetics.

3. Genetics and Heredity
Genes that code for different versions of a trait (For example: hitchhikers’ thumb or regular thumb) are called alleles.

4. Phenotypes The physical appearance of an organism.
Example: tongue roller , blood type, no hitchhikers’ thumb.
Blood Types
A, B
AB, O

5. Genotypes
The alleles a person actually has and is shown by the use of capital and lowercase letters.
Example: TT, Tt, tt,

6. Alleles can be… DOMINANT or recessive
Dominant alleles always show their trait, no matter what the other trait from the other parent is.
Dominant alleles are shown as capital letters.
Examples: T= Hitchhiker’s Thumb

7. Alleles can be… DOMINANT or recessive
Recessive alleles do not show their trait unless both alleles are recessive.
Recessive alleles are shown as lower case letters.
Example: t= Regular Thumb

8. Genotypes
Homozygous- an organism has two alleles that are the same (Homo=same)
Example: TT, tt

9. Genotypes
Heterozygous- an organism has two different alleles (Hetero= Different)
Example: Tt

10. Natural Selection, Charles Darwin, & Artificial Selection

11. Fundamentally Genetics Lab
Tongue Rolling
Earlobes that hang
Attached Earlobes
Widow’s Peak