Genetic Unit - Vocabulary
Chromosome: Long threads of genetic material found in the nucleus of the cell
Sister Chromatids: A chromosome and its duplicate, attached to one another by a centromere. The pair remains attached until separated by meiosis.
Mitosis: A type of cell division in which a daughter cell receives the same number of chromosomes as the parent cell
Meiosis: Two stage cell division in which the chromosomes number of the parental cell is reduced by half. Meiosis is the process by which gametes are formed.
Gametes: Sex cells that have haploid chromosome number
Haploid: Refers to the number of chromosomes in a gamete
Diploid: Refers to twice the number of chromosomes in a gamete. Every cell of the body, with the exceptions of sex cells, contains a diploid chromosome number.
Homologous Chromosomes: Paired chromosomes similar in shape, size, gene attachment, and gene information
Zygote: A cell resulting from the union of a male and female sex cell, until it divides and then is called an embryo.
Tetrad: A pair of homologous chromosomes, each with two chromatids
Crossing Over: The exchange of genetic material between two homologous chromosomes.
Hybrids: Offspring that differ from their parents in one or more traits. Interspecific hybrids result from the union of two different species.
Alleles: Two or more alternate forms of a gene. The alleles are located at the same position on one of the pairs of homologous chromosomes.
Dominant: Alleles of this type determine the expression of the genetic trait in offspring.
Recessive: Alleles of this type are overruled by dominant alleles, which determine the genetic trait.
Phenotype: The observable traits of an organism that arise because of the interaction between genes and the environment.
Genotype: The alleles an organism contains
Homozygous: A genotype in which both alleles of a pair are the same
Heterozygous: A genotype in which both alleles of a par are different.
Monohybrid cross: A cross that involves one allele pair of contrasting traits
Punnett square: A chart used by geneticists to show the possible combination of alleles in offspring.
Dihybrid Cross A type of cross that involves two genes, each consisting of nonidentical alleles.