Homologous-Chromosome pairs of the same length, centromere position, and staining pattern, that possess alleles for the same traits at corresponding locations.
Gametes-a sex cell, either an egg or a sperm, formed by meiosis.
Haploid-a cell containing only one set of homologous chromosomes.
Diploid-a cell containing two sets of homologous chromosomes, one set inherited from each parent.
Meiosis-two successive nuclear divisions (with corresponding cell divisions) that produce gametes (in animals) or sexual spores (in plants) having half of the genetic material of the original cell.
Crossing over-during prophase I of meiosis, the breakage and exchange of corresponding segments of homologous chromosomes at one or more sites along their length, resulting in genetic recombination. Genetic recombination-presence of new combinations of alleles in a DNA molecule as the result of crossing over at meiosis, chromosomal alterations, or gene mutations.
Spores-a one-celled reproductive body that is usually resistant to harsh environmental conditions and may remain dormant for long periods; asexual in some organisms and may initiate growth of a new organism under favorable conditions; sexual in other organisms and must unite with another before producing a new organism.
Carpel-the female reproductive organ of a flower, consisting of the stigma, style, and ovary.
Ovules-a structure that develops in a plant ovary and contains the egg.
Stamens-the pollen-producing male reproductive organ of a flower; consists of an anther and filament.
Pollination-the placement of pollen by wind or animal vectors onto the stigma of a carpel; prerequisite to fertilization.
Embryo-an organism in its earliest stages of development.
Ovaries-the primary reproductive organs of a female; egg-cell-producing organs.
Testes-the primary reproductive organs of a male; sperm-cell-producing organs.
Oviducts-a tube that leads from an ovary to the uterus
Uterus-a hollow muscular organ, located in the female pelvis, in which a fetus develops.
Vagina-a tubular organ that leads from the uterus to the opening of the female reproductive tract.
Menstrual cycle-the female reproductive cycle that is characterized by regularly recurring changes in the uterine lining.
Estrogen-a hormone that stimulates the development of female secondary sexual characteristics.
Progesterone-a female hormone, secreted by the corpus luteum and the placenta, that prepares the uterus for pregnancy and the breasts for lactation.
Ovulation-the release of an egg cell from a mature ovarian follicle.
Placenta-a structure in the pregnant uterus for exchange of materials between a fetus and the mother’s blood supply; formed from the uterine lining and embryonic membranes.
Scrotum-a pouch of skin that encloses the testes.
Androgens-a male sex hormone, such as testosterone.
Testosterone-a male sex hormone secreted by the testes.
Puberty-the stage of development in which the reproductive organs become functional.
