Nucleus: The organelle within a cell that contains DNA
Deoxyribonucleic acid: A self-replicating molecule present in nearly all living organisms. It is the main constituent of chromosomes.
Chromosome: Threadlike structure of nucleic acids and protein found in the nucleus of most living cells. They carrying genetic information in the form of genes.
Homologous: Having the same structural features and pattern of genes.
Gene: A short length of DNA that carries the genetic code for a particular characteristic or cell activity.
Allele: Different forms of the same gene. They can be dominant or recessive.
Nucleotide: Nucleotides form the basic structural unit of DNA. Composed of a sugar, a phosphate, and a base.
Base: Parts of DNA that are involved in pairing. The bases on DNA are cytosine, quanine, adenine, and thymine.
Amino Acid: Compounds made from amine (-NH) and carboxylic acid (-COOH) functional groups, along with a side-chain specific to each amino acid.
Protein: Large, biologically important polymers comprised of sequences of amino acids.
Trait: A genetically determined characteristic or condition
Allele: Different forms of the same gene. They can be dominant or recessive.
Dominant: An allele which is always expressed, even if only one is present. Dominant alleles are assigned uppercase letters
Recessive: An allele that is only expressed when both alleles are recessive in the organism. Recessive alleles are assigned lowercase letters
Trait: A genetically determined characteristic.
Genotype: The specific alleles that occur in an organism,
Phenotype: The observable characteristics of an organism resulting from its genotype
Pure-bred: An organism that has two alleles of the same type for a particular trait.
Homozygous: Having two alleles of the same type for a particular trait.
Heterozygous: Having two alleles of different types for a particular trait.
Pedigree chart: A chart or diagram showing the phenotypes of related individuals.
Test cross: A cross between an organism whose genotype for a certain trait is unknown and an organism that is homozygous recessive for that trait.
Genetic variation: The genetic differences between organisms within a population. It can be continuous or discontinuous.
Meiosis: A type of cell division used to produce cells (gametes) for sexual reproduction that are different to each other, and to the parent cell.
Gamete: Male or female reproductive cells (sperm and ova) that contain half the number of chromosomes compared to the parent cell.
Zygote: A fertilised ova (egg) that contains a full set of chromosomes,
Asexual Reproduction: Reproduction involving only one parent (usually a female). The offspring are genetically identical to the parent and to each other.
Sexual Reproduction: Reproduction involving only two parents. The offspring are different to the parent and to each other.
Mutation: A change in the base sequence of DNA. (They do not produce zombies or ninja turtles).
Crossing over: A process that occurs during meiosis whereby sections of homologous chromosomes are exchanged.
Independent assortment: A process that occurs during meiosis whereby the chromosomes line up in random order before separating, creating unique gametes.