Science / Biology Glossary

Chromatin: A complex of DNA and protein in eukaryotic cells that is dispersed throughout the nucleus during interphase and condensed into chromosomes during meiosis and mitosis.

Chromosome Theory Of Inheritance: Holds that chromosomes are the cellular components that physically contain genes; proposed in 1903 by Walter Sutton and Theodore Boveri.

Chromosomes: Structures in the nucleus of a eukaryotic cell that consist of DNA molecules that contain the genes.

Chrysophytes: Protistan division that is referred to as the golden brown algae; includes the diatoms.

Cilia: Hair-like organelles extending from the membrane of many eukaryotic cells; often function in locomotion (sing.: cilium).

Circadian Rhythms: Biorhythms that occur on a daily cycle.

Circulatory System: One of eleven major body organ systems in animals; transports oxygen, carbon dioxide, nutrients, and waste products between cells and the respiratory system and carries chemical signals from . . . View Full Definition

Classes: Taxonomic subcategories of phyla.

Clavicle: The collar bone.

Cleavage Furrow: A constriction of the cell membrane at the equator of the cell that marks the beginning of cytokinesis in animal cells. The cell divides as the furrow deepens.

Climax Community: The stage in community succession where the community has become relatively stable through successful adjustment to its environment.

Clitoris: A short shaft with a sensitive tip located where the labia minora meet; consists of erectile tissue and is important in female sexual arousal.

Clone: An exact copy of a DNA segment; produced by recombinant DNA technology.

Closed Circulatory System: A system that uses a continuous series of vessels of different sizes to deliver blood to body cells and return it to the heart; found in echinoderms and vertebrates.

Closed Community: A community in which populations have similar range boundaries and density peaks; forms a discrete unit with sharp boundaries.

Codominance: A type of inheritance in which heterozygotes fully express both alleles.

Codon: A sequence of three nucleotides in messenger RNA that codes for a single amino acid.

Coelom: In animals, a body cavity between the body wall and the digestive system that forms during preadult development.

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