Term | Definition |
Somatic Cell | Cell that makes up all of the body tissues and organs, except gametes. |
Gamete | Sex cell; an egg or a sperm cell. |
Homologous Chromosome | Chromosomes that have the same length, appearance, and copies of genes, although the alleles may differ. |
Autosome | Chromosome that contains genes for characteristics not directly related to the sex of the organism. |
Sex Chromosome | Chromosome that directly controls the development of sexual characteristics. |
Sexual Reproduction | Process by which two gametes fuse and offspring that are a genetic mixture of both parents are produced. |
Fertilization | Fusion of an egg and sperm cell. |
Diploid | Cell that has two copies of each chromosome, one from an egg and one from a sperm. |
Haploid | Cell that has only one copy of each chromosome. |
Meiosis | From of nuclear division that divides a diploid cell into haploid cells; important in forming gametes for sexual reproduction. |
Gametogenesis | Process by which gametes are produced through the combination of meiosis and other maturational changes. |
Sperm | Male gamete. |
Egg | Female gamete. |
Polar Body | Haploid cell produced during meiosis in the female of many species; these cells have little more than DNA and eventually disintegrate. |
Trait | Characteristic that is inherited. |
Genetics | Study of the heredity patterns and variation of organisms. |
Purebred | Type of organism whose ancestors are genetically uniform. |
Cross | Mating of two organisms. |
Law of Segregation | Mendel's first law, stating that (1) organisms inherit two copies of genes, one from each parent, and (2) organisms donate only o copy of each gene in their gametes because the genes separate during gamete formation. |
Gene | Specific region of DNA that codes for a particular protein. |
Allele | Any of the alternative forms of a gene that occurs at a specific place on a chromosome. |
Homozygous | Characteristics of having two of the same alleles at the same locus of sister chromatids. |
Heterozygous | Characteristic of having two different alleles that appear at the same locus of sister chromatids. |
Genome | Al of an organism's genetic material. |
Genotype | Collection of all of an organism's genetic information that codes for traits. |
Phenotype | Collection of all of an organism's physical characteristics. |
Dominant | Allele that is expressed when two different alleles are present in an organism's genotype. |
Recessive | Allele that is not expressed unless two copies are present in an organism's genotype. |
Punnett Square | Model for predicting all possible genotypes resulting from a cross, or mating. |
Monohybrid Cross | Cross , or mating, between organisms that involves only one pair of contrasting traits. |
Testcross | Cross between an organism with an unknown genotype and an organism with a recessive phenotype. |
Dihybrid Cross | Cross, or mating, between organisms involving two pairs of contrasting traits. |
Law of Independent Assortment | Mendel's second law, stating that allele pairs separate from one another during gamete formation. |
Probability | Likelihood that a particular event will happen. |
Crossing Over | Exchange of chromosome segments between homologous chromosomes during meiosis 1. |
Genetic Linkage | Tendency for genes located close together on the same chromosome to be inherited together. |