Genetics Vocabulary Genetics- the scientific study of heredity. Heredity- The passing of traits from parents to offspring. Dominant allele- An allele whose trait always shows up in the organism when the allele is present. Recessive allele- An allele that is masked with when a dominant allele is present. Genes- A segment of DNA on a chromosome that codes for a specific trait. Genotype-An organism’s genetic makeup, or allele combinations. Phenotype- An organisms physical appearance, or visible traits. Homozygous-Having two identical alleles for a trait. Heterozygous- Having two different alleles for a trait. Chromosome- A thread like cellular structure that carries the information that controls inherited characteristics. DNA-The Genetic material that carries information about the organism and that is passed from parent to offspring. Sexual Reproduction- The reproductive process that involves two parents who combine their genetic material to produce a new organism, which differs from both parents. Asexual Reproduction- The production of offspring by a single parent, without the union of a sperm cell and an egg cell. Reproduction- The process by which living things produce new individuals of the same type. Egg- A female sex cell. Sperm-A male sex cell. Fertilization- The joining of a sperm cell and an egg cell. Adaptation- A characteristic that helps an organism survive in its environment and reproduce. Species- A group of similar organism whose members can mate with one another and produce fertile offspring. Biodiversity- The number of different species in an area. Extinction- The disappearance of all members of a species from earth. Nucleus- The central core of an atom containing protons and usually neutrons; also, the control center of the cell that directs the cells’ activities and determines the cell’s characteristics. Hybrid- An organism that has two different alleles for a trait; an organism that is heterozygous for a particular trait. Purebred- An organism that always produces offspring with the same form of traits as itself. Inherited Trait- An offspring’s phenotype inherited by its parents. (Having red hair) Acquired Trait- A trait that is learned. (How to make pizza) Selective Breeding- The process of selecting a few organisms with desired traits to serve as parents of the next generation.