Reproduction - Key terms
ALTERNATION OF GENERATIONS:
A process whereby plant generations alternate as sexual and asexual reproducers—gametophytes and sporophytes, respectively.
ASEXUAL REPRODUCTION:
One of the two major varieties of reproduction (along with sexual reproduction), In contrast to sexual reproduction, which involves two organisms, asexual reproduction involves only one. Asexual reproduction occurs when a single cell divides through mitosis to form two daughtercells, which are genetically identical to the parent cell.
BINARY FISSION:
The process in asexual reproduction whereby a single cell divides to form two daughter cells that are genetically identical to the parent cell.
CLONE:
A cell, group of cells, or organism that contains genetic information identical to that of its parent cell or organism.
CLONING:
A specialized genetic process whereby clones are produced. Cloning is a form of asexual reproduction.
CHROMOSOME:
A DNA-containing body, located in the cells of most living things, that holds most of the organism's genes.
CROSS-POLLINATION:
The transfer of pollen from one plant to another.
CYTOPLASM:
The material inside a cell that is external to the nucleus.
DIPLOID:
A term for a cell that has the basic number of doubled chromosomes.
DNA:
Deoxyribonucleic acid, a molecule in all cells, and many viruses, that contains genetic codes for inheritance.
EGG CELL:
A female gamete.
ENZYME:
A protein material that speeds up chemical reactions in the bodies of plants and animals without itself taking part in or being consumed by those reactions.
FERTILIZATION:
The process of cellular fusion that takes place in sexual reproduction. The nucleus of a male reproductive cell, or gamete, fuses with the nucleus of a female gamete to produce a zygote.
GAMETE:
A reproductive cell—that is, a mature male or female germ cell that possesses a haploid set of chromosomes and is prepared to form a new diploid by undergoing fusion with a haploid gamete of the opposite sex. Sperm and egg cells are, respectively, male and female gametes.
GAMETOPHYTE:
In alternation of generations, a gametophyte is a plant that reproduces sexually.
GERM CELL:
One of two basic types of cells in a multicellular organism. In contrast to somatic or body cells, germ cells play a part in reproduction.
HAPLOID:
A term for a cell that has half the number of chromosomes that appear in a diploid or somatic cell.
MEIOSIS:
The process of cell division that produces haploid genetic material. Compare with mitosis.
MITOSIS:
A process of cell division that produces diploid cells, as in asexualreproduction. Compare with meiosis.
NUCLEUS:
The control center of a cell, where DNA is stored.
OVARY:
Female reproductive organ that contains the eggs.
OVULE:
Female haploid gametophyte of seed plants, which develops into a seed upon fertilization by a pollen grain.
PARTHENOGENESIS:
A type of reproduction that involves the development of a gamete without fertilization. In other words, a sex cell (usually female) is reproduced without actual intercourse between male and female.
POLLEN:
Male haploid gametophyte of seed plants (including angiosperms and gymnosperms), which unites with the ovule to form a seed. Pollen is a fine, powdery substance consisting of microscopic grains.
POLLINATION:
The transfer of pollen from the male reproductive organs to the female reproductive organs of a plant. Pollination precedes fertilization. See also cross-pollination.
REGENERATION:
A biological process among some lower animals whereby a severed body part is restored by the growth of a new one.
SEXUAL REPRODUCTION:
One of the two major varieties of reproduction (along with asexual reproduction). In contrast to asexual reproduction, which involves a single organism, sexual reproduction involves two. Sexual reproduction occurs when male and female gametes undergo fusion, a process known as fertilization, and produce cells that are genetically different from those of either parent.
SOMATIC CELL:
One of two basic types of cells in a multicellular organism. In contrast to germ cells, somatic cells (also known as body cells) are not involved in reproduction; rather, they make up the tissues, organs, and other parts of the organism.
SPERM CELL:
A male gamete.
SPOROPHYTE:
In alternation of generations, a sporophyte is a plant that reproduces asexually.
ZYGOTE:
A diploid cell formed by the fusion of two gametes.