Download Document

Genetics Quiz Study Guide
 Genetics – the study of heredity
Heredity – the passing of traits from parent to offspring
o
Trait – a characteristic of an organism controlled by a gene

 Gene – segment of DNA on a chromosome controlling the inheritance of traits
 Chromosomes – strands of DNA and protein found in the nucleus of a cell carrying the code for the
characteristics of an organism
 Dominant – form of a trait that appears to overshadow or mask another form of the trait
 Recessive – form of a trait that can disappear in a population, but can reappear in future generations
 Alleles – the different forms a gene may have for a trait
o
o
Homozygous – an organism that has two identical alleles for a trait

Purebred – pair of chromosomes containing alleles for the same trait

Homologous – a synonym for homozygous
Heterozygous – an organism that has two different alleles for a trait

Hybrid – a synonym for heterozygous
 Phenotype – a physical trait that shows as a result of an organism’s particular genotype
 Genotype – the genetic makeup of an organism for a trait; alleles in a gene pair
 Punnett square – a tool for predicting possible offspring
 Probability – the mathematical chance that an event will occur
 Egg – female sex cell
 Sperm – male sex cell
 Variation – occurrence of a trait that makes individuals different from members of the same species

There are 23 pairs (46 total) of chromosomes in the human body.

The 23rd pair of chromosomes is the sex chromosomes.

For a male, the sex chromosomes are XY.

For a female, the sex chromosomes are XX.
Example:
Trait – Height
Possible gene pairs – TT, Tt, tt
Homozygous genotype – TT, tt
Phenotype for TT – tall
Possible alleles – T = tall; t = short
Dominant – T
Recessive – t
Heterozygous genotype – Tt
Phenotype for Tt – tall
Phenotype for tt – short