a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

deoxyribonucleic acid, a self-replicating material which is present in nearly all living organisms as the main constituent of chromosomes. It is the carrier of genetic information.

a distinct sequence of nucleotides forming part of a chromosome, the order of which determines the order of monomers in a polypeptide or nucleic acid molecule which a cell (or virus) may synthesize.

In genetics, a trait that will appear in the offspring if one of the parents contributes it.

In genetics, a trait that must be contributed by both parents in order to appear in the offspring. Recessive traits can be carried in a person's genes without appearing in that person. For example, a dark-haired person may have one gene for dark hair, which is a dominant trait, and one gene for light hair, which is recessive. It is thus possible for two dark-haired parents to have a light-haired child, provided each parent contributes a gene for light hair.

the transmission of genetic characters from parents to offspring: it is dependent upon the segregation and recombination of genes during meiosis and fertilization and results in the genesis of a new individual similar to others of its kind but exhibiting certain variations resulting from the particular mix of genes and their interactions with the environment.

one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

having two different alleles of a particular gene or genes

The formation of sex cells is a central part of human reproduction: In fertilization, an egg cell and a sperm cell combine. These sex cells are also called reproductive cells or gametes. Sperm cells are produced in men's testicles and egg cells are produced in women's ovaries.

the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.

the genetic constitution of an individual organism.

The Punnett square is a square diagram that is used to predict the genotypes of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach. The diagram is used by biologists to determine the probability of an offspring having a particular genotype.