1. Genes and Alleles
1. Introduction
1a. You get half your chromosomes from your mother and the other half from your father.

2. Genes and Alleles
1. Introduction
1b. While you get an equal number of chromosomes from your mother and father the genes on those chromosomes are not equal when it comes to the influence they have on your traits.

3. Genes and Alleles
2. Genes come in pairs.
2a. Each chromosome carries genes that give instructions for the same trait.
2b. Example: Both chromosomes in one pair will have a gene that tell the body how to build eyelashes.

4. Genes and Alleles 2. Genes come in pairs.
2c. These different varieties of a gene are called alleles.
A person can have:

6. Genes and Alleles
3. Dominant and recessive alleles.
3a. A dominant allele is one that, if present in a pair of alleles, is always expressed.
- In eyelashes LONG is the dominant trait (E)

7. Genes and Alleles
3. Dominant and recessive alleles.
3b. A recessive allele is one that is expressed by an individual only if it is paired with another recessive allele.
- In eyelashes short is the recessive trait (e)

8. Genes and Alleles
3. Dominant and recessive alleles.

9. Checkpoint Brown eyes are dominant = B Blue eyes are recessive = b
3c. If a mother passes down a brown allele (B), and the father passes down a blue allele (b). What color will the offspring’s eyes be?

10. Agenda 1/28/13 Assignment: Homework: Genes Come in Pairs
Protein Synthesis Take Home Exam