Twin studies: Monozygotic=identical

                Dizygotic=fraternal

Study done on identical and fraternal twins to measure how much a persons traits are affected by genetics, and how much are affected by their environment.

Adoption studies: Study done on adopted children to determine the roles of nature vs nurture in development.

Twin: Studies find that multiple measures of personality and temperament, occupational and leisure-time interests and social attitudes, (identical) twins reared apart are about as similar as (identical) twins reared together, the twins' genes had strongly guided their genetic development.

Resemblence: MZ >DZ = high heritability

                  MZ = DZ =low heritability

Adoption: Studies find that there is little similarity between adopted kids and their siblings, and great similarity between the adopted children and their biological parents, showing that their development was based off their genes.

If adoptedkids resemble biological parents more than adoptive parents, we assume high heritability.

Prenatal environment

Twin: MZ twins share chorion and blood supply (more similar prenatal env compared to DZ twins) so could be genetics or prenatal environment.

Adoptive: Biological children of low IQ, or mentally ill parents tend to have similar problems even if raised by "great" adoptive parents. Could be genes, BUT could be reflection of poor prenatal environment.

Genes predispose you to behaviors and to different treatment by others.

- Multiplier effect

Ex: Mice in elevated plus maze, some genetic strains tend to stay in walled arms, others venture out onto arms. BUT sometimes a strain that is unadventurous in one lab is more adventurous in another. Depends on exactly how the researchers handle the mice, maybe odors in the room, ect.

Ex:Phenylketonuria (PKU), mental retardation due to genetic inability to metabolize a certain amino acid.

Moral of story: inherited or genetic does not equal unmodifiable!

• If a male gets this gene, he will display the trait
• Females must get both of her X chromosomes to display the trait
• If a female has it on one X chromosome and NOT on the other, she is a carrier.

Examples:

1. Fragile X syndrome
2. Red-green color blind
3. Duchenne muscular dystrophy
4. Hemophilia

What is a sex-limited gene?

Examples of sex-limited genes:

Gene that is present in both sexes but has an effect (only mostly) in one sex

Examples

1. Chest hair (men)
2. Brest size (women)

• Unit of heredity in a living organism

• Sequence of DNA

• Contains information on heredity characteristics

Is and organized building of DNA and protein that is found in cells, contains many genes.

We have 46 chromosomes:

                     - 22 paired autosomal chromosomes

- 2 sex chromosomes

 XX- femal

XY- Male

Identical set of genes on the 2 chromosomes

-person with identical set of genes on the 2 chromosomes is homozygous for that gene

Unmatched pair of genes on the 2 matched chromosomes

-person with unmatched pair of genes on the 2 matched chromosomes is heterozygous for that gene.

Gene that shows strong effect in the heterozygous or homozygous condition

ex: tongue rolling is autosomal dominant

so is huntingtons disease

Gene that shows strong effect only in homozygous condition

ex: attached earlobes are recessive

The process by which traits becomes more or less common in a population due to consistent effects upon the survival or reproduction of their bearers. It is the "Key Mechanism" of evolution

If certain individuals are more successful live to reproductive age -> their genes will become more prevalent