DNA/Genetics Vocabulary
Trait-A characteristic that an organism can pass on to its offspring through its genes
Heredity-The passing of traits from parents to offspring
Chromosomes-Structures that carry the genetic information in the form of DNA molecules
Genetics-The scientific study of heredity
Purebred-An organism that always produces offspring with the same form of a trait as the parent
Gene-A segment of DNA on a chromosome that codes for a specific trait
Alleles-One of the forms of a gene that controls a particular trait. Most traits are determined by 2
alleles, 1 from each parent.
dominant allele-An allele whose trait always shows up in the organism when the allele is present.
recessive allele-An allele that is masked when a dominant allele is present Present only when the
dominant gene is absent
Hybrid-An organism that has two different alleles for a trait; an organism that is heterozygous for a
particular trait
Probability-The likelihood that a particular event will occur
Punnett square-A chart that shows all the possible combinations of alleles that can result from a
genetic cross
Phenotype-An organism’s physical appearance, or visible traits
Genotype-An organism’s genetic makeup, or allele combinations, cannot see
Homozygous-Having two identical alleles for a trait
Heterozygous-Having two different alleles for a trait
Dominance- 2 dominant traits are present
Complete Dominance-Dominant gene is expressed, unless not present, then recessive gene is
expressed
Incomplete Dominance-Genes produce a trait somewhere in between the traits of the 2 parents
Sperm-A male sex cell
Egg-A female sex cell
Meiosis-The process that occurs in sex cells (sperm and egg) by which the number of chromosomes
is reduced by half
messenger RNA-RNA that copies the coded message from DNA in the nucleus and carries the
message into the cytoplasm
transfer RNA-RNA in the cytoplasm that carries an amino acid to the ribosome and adds it to the
growing protein chain
Mutation-A change in a gene or chromosome
Punnett Square- A chart that predicts the chances of offspring inheriting a particular trait from their
parents