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