1. Emily Moler

5. Chromosomes Strand of DNA that carry genetic information There are 46 in each cell (except for the sex cells) and are found in 23 pairs, each half of the pair comes from either your mom or dad.

6. Fertilization This is when a parent will give their genes to their child. The parents create a zygote, which is a single cell formed by the union of a sperm and an egg.

7. Genes DNA segments that serve as the key functional units in hereditary transmission. They are found on chromosomes.

8. More on Chromosomes Each of the 23 chromosome pairs can be scrambled in over 8 million (2 to the 23 rd power) ways. This is not including any mutations or crossing overs that may occur. So because of this :

9. Everything is a matter of probability!!

10. Ways to pair up: Homozygous This is when the genes from the parents are the exact same. Heterozygous This is when the genes from the parents are different.

11. Because of this difference there are dominant and recessive genes. These are always shown during a heterozygous pairing. These are masked during a heterozygous pairing. Dominant: Recessive :

12. Identical Twins100 % Fraternal twins Brother or sister Parent or child First-degree relatives50 % Grandparent or grandchild, Uncle, aunt, nephew, or niece Half-brother or half- sister Second-degree relatives25% First CousinThird-degree relatives12.5 % Second CousinFourth-degree relatives6.25% Unrelated0%

13. Genotype v. Phenotype A person’s genetic makeup How a person’s genotype is physically manifested. Genotype: Phenotype : Cannot be changed Can be changed by time or environment

14. Phenotype... Some different genotypes may blend together to form an “Averaged out” phenotype, for example hair or eye color.

15. Polygenic traits These are influenced by more than one pair of genes. For example, the skin color is influenced by about 3 to 5 pairs of genes.