Punnet Square I
Punnet Square II
Making Babies
Traits Lab
Mapping Traits
Protein Synthesis

Genetic SLC
DNA Replication

Genetics Facts

Student Objectives
DNA Structure
Protein Syntheses & Bioengineering

Genetics Sites


Return SAS Home
e-mail Kevin C. Hartzog


Vocabulary 1

(Vocabulary definitions developed by Biology Staff, Thurgood Marshall Academic High School, 1999-2001)

Genetics: The study of inheritance.

Trait: A physical characteristic we can describe.
Example 1: Pea shape is a trait.
Example 2: Eye color is a trait.

Gene: A particular sequence of DNA located on a specific point on a chromosome, that tells a cell to produce a specific protein.

Example 1: Gene for hair color.
Example 2: Gene for blood type.

Alleles: are a variation of a gene and are located on chromosomes.

For the gene for eye color, one variation could be a brown allele, and another variation could be a blue allele. Notice that each allele is located on the same place on the chromosome (the location of the gene for eye color).

Example 1: For pea plant height H = tall plants or h = short plants.
Example 2: For eye color E = brown eyes or e = blue eyes.

Dominant: an allele that is shown even if it is present in only one copy.

Example: Being able to roll your tongue is dominant over not being able to roll your tongue. If we chose the letter "T", we could show it this way:

T = tongue roller, t = not being able to roll their tongue.

Recessive: An allele that is shown ONLY if it is present in two copies.

Example: In the gene for eye color, the blue allele is recessive. A person with blue eyes will have two blue alleles.

ee = blue eyes

Genotype: MUST be two alleles that RESULT in a particular trait or disorder.

Example 1: Gene for pea plant height -- Genotypes could be HH, or Hh, or hh
Example 2: Gene for eye color -- Genotypes could be EE, or Ee, or ee