Chapter 2

How many genes do humans have?

22,000 to 22,000 genes

What is the likelihood (or chances) of having a blue eyed child if one parent has brown and the other has blue eyes?

25%

How many chromosomes are in each human cell?

46 Chromosomes arranged in 23 pairs

DNA

A complex double-helix molecule that contains genetic information

Dominant-Recessive genes principle

A dominant gene always exerts its effects, overriding the potential influence of the recessive gene. A recessive gene only exerts influence if both genes in a pair are recessive.

X-Linked inheritance occurs when....

A mutated gene is carried on the X chromosome. More likely to affect males. Females have a 2nd X chromosome that is likely to be unchanged, men dont.

Genotype

A persons genetic material

Genetic expression

Affected by environment

Natural Selection

An evolutionary process by which those individuals of a species that are best adapted are the ones that survive and reproduce

Human Genome Project

Attempted to map the human genome

Adaptive Behavior

Behavior that promotes an organisms survival

Paul Bates

Benefits of evolutionary selection decrease with age. Natural selection tied to reproduction fitness

Proteins

Building blocks of cells and regulators that direct the body's processes

How is a child's sex determined?

By the 23rd pair of chromosomes XX=female, XY=male

Meiosis

Cell division that forms sperm and eggs. Each cell divides twice, forming four cells with 23 unpaired

Polygenetic Inheritance

Characteristics that are determinded by the interaction of many different genes

Genome

Complete set of developmental instructions for the making of a human organism

Identical (mono zygotic) twins

Develop from a single zygote that splits into two

Fraternal (dizygotic) twins

Develop from separate eggs and sperm

Evolutionary Psychology

Emphasizes the importance of adaptation, reproduction, and "survival of the fittest" in shaping behavior

Fertilization

Fusing of sperm and egg to create a zygote. Creates one set paired chromosomes (23 from each parent)

Example of X linked Inheritance

Hemophilia and Fragile-X syndrome

Are chromosomes in zygotes exact copies?

No

Phenotype

Observable characteristics. A range of phenotypes can be expressed for each genotype

Genetic Imprinting

Occurs when genes have differing effects depending on whether they are inherited from the mother or the father.

Why do humans live so long after reproduction?

Older people improve the survival rate of babies

Mitosis

Reproduction of cells

Fit

The ability to bear offspring that survive long enough to bear offspring of their own

Chromosomes

Thread-like structures made up of DNA

Genes

Units of hereditary information in each chromosome. Genes direct cells to reproduce themselves and to assemble proteins