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Calyx
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In flowers, the sepals that protect the flowering body. |
Carbohydrate
One of four main classes of macromolecules used in biological systems. They generally have the form of CH2On, and are used for energy storage.
Catalysis
A chemical reaction that is accelerated by a catalyst.
Cellulose
The material that makes up plant cell walls.
Centriole
An organelle involved in the formation and organization of microtubules. They are shaped like a cylinder, and consist of nine triplets (groups of three) of microtubules around two single microtubules. A pair of centrioles is necessary for spindle formation during nuclear division. Centrioles have their own DNA and are thought to be derived from bacteria.
Centromere
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A specialized region on a chromosome where spindle fibers form during cell division. |
Centrosome
The region in a cell where two centrioles form the basis of microtubule organization during cell division.
Chitin
A nitrogen-containing polysaccharide found in some animals and the cell walls of many fungi and some protoctists. Chitin is also found in the outer covering of arthropods, called the cuticle.
Chitinous
Anything that contains chitin.
Chlorophyll
The green, light-absorbing pigment found in plants, and in some other organisms, which is used for photosynthesis.
Chondrite
A stony meteor that contains chondrules.
Chondrule
Very small, glassy silicate structures commonly found in chondrites.
Chromatic aberration
A false coloration in lens caused by wavelengths that are refracted or reflected by different amounts.
Chromatid
One of the two daughter strands that form after a chromosome has self-replicated.
Cilium
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A short external organelle that consists of an axoneme built of nine pairs of microtubules surrounding an inner pair. This structure is anchored to the eukaryotic cell by a kinetosome. Generally, cilia (plural form) are associated in a local area on a cell. |
Clavicle
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In anatomy, the bone that braces the shoulder, and allows the forelimb (or arm) to swing freely from the trunk of the body. Also known as the collarbone. Image courtesy of Handball City: Shoulder Injuries. |
Cleavage
In reproduction, refers to the cell division of a zygote. In biochemistry, refers to the severing of bonds between two or more macromolecules.
Coccidia
An order of protozoans that are intracellular parasites in many vertebrates.
Codon
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The basic unit of genetic structure that has three nucleotide sequences of mRNA which is translated into one amino acid during protein synthesis. |
Commensal
Any organism that is involved in a commensalist symbiotic relationship.
Commensalism
A type of symbiosis where one (or more) species benefits greatly, while another species remains unaffected. An example of commensalism can be found with oysters which attach themselves to mangrove roots. The mangrove roots provide a stable surface for the oysters to live on, which is of great benefit, and the mangrove itself remains unaffected.
Concentration gradient
A term that refers to the difference in amount of elements (usually molecules) between two adjoining regions.
Corm
In plants, a bulb-like stem that sends out a root when the growing season begins.
Cotyledon
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The first leaf that is borne on embryonic seed plants. Plants that have a cotyledon can be separated into two groups: monocots and dicots. Image can be found at Morphology of the Monocots. |
Cranial Nerves XI
Also known as the accessory nerves. A pair of nerves from the brainstem and the spinal cord that supply motor impulses to the throat muscles for swallowing and speech.
Culture
Any organism or living cell that is grown in a laboratory medium (such as agar).
Cuticle
Any type of protective covering secreted by the epidermis, or outer layer of cells. In plants, the cuticle is a waterproof, waxy layer called cutin. Some animals, such as endoparasites (tapeworms, flukes), produce a non-waterproof secretion. Arthropods produce a chitinous cuticle which is waterproof, and also serves as an exoskeleton.
Cutin
A group of substances chemically related to fatty acids that form a continuous cuticle layer on the epidermis of plants. It is waterproof, and helps reduce water loss by transpiration, and also provides a protective barrier against parasites.
Cytosine
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A nitrogenous base that pairs with guanine in both DNA and RNA. When you see a string of letters that are used to describe DNA, such as AGTCCGTTATATTGC, "C" stands for cytosine. |
Cytoskeleton
A network of filaments that provide a structure for cytoplasm.
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