Heredity and Behavior: Is it All

in the Genes?Emily Moler

BIOLOGICAL MAKEUP IS INTIMATELY RELATED TO YOUR BEHAVIOR.

• Every cell in your body contains enduring messages from your mother and father• These are found on the

chromosomes that lie within nucleus

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.

FertilizationThis 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.

Genes• DNA segments

that serve as the key functional units in hereditary transmission.

• They are found on chromosomes.

More on Chromosomes• Each of the 23

chromosome pairs can be scrambled in over 8 million (2 to the 23rd power) ways.

• This is not including any mutations or crossing overs that may occur.So because of

this:

Everything is a matter of probability!!

Ways to pair up:Homozy

gousThis is when the genes from the parents are the exact same.

HeterozygousThis is when the genes from the parents are different.

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:

Identical Twins 100 %

Fraternal twins Brother or sisterParent or child

First-degree relatives 50 %

Grandparent or grandchild, Uncle,

aunt, nephew, or nieceHalf-brother or half-

sister

Second-degree relatives 25%

First Cousin Third-degree relatives 12.5 %

Second Cousin Fourth-degree relatives 6.25%

Unrelated 0%

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

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

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.