Dr. Paul's Virtually Biology Show.

www.jccc.net/~pdecell

C. 

Calorie. A unit of energy used in biology. One calorie with a small "c" is roughly defined as the amount of heat it takes to raise one cubic centimeter of water from 14.5 degrees to 15.5 degrees centigrade. The food Calorie "C" is one thousand regular calories or one kilocalorie. 
Calvin-Benson cycle. Part of the dark reactions of photosynthesis where carbon is incorporated into the plant's metabolic pathway from carbon dioxide and used to make PGAL. 
C-AMP(Cyclic adenine monophosphate). An important secondary messenger in cells. One of its functions is to set up a series of chemical reactions in the cytoplasm of cells in response to non steroid hormones joining with the hormone receptor on the cell membrane. 
Capillary. A capillary is a tiny blood vessel with walls only a single cell thick. Gas and nutrient exchange between the blood and the rest of the body take place only though the capillaries! 
Carbohydrate. A carbon compound consisting of carbon hydrogen and oxygen in the molecular ratio of approximately one carbon : two hydrogens: one oxygen. Sugars and compounds built from sugars are the most commonly encountered carbohydrates. 

Carbon. An element with an atomic number of 6 and an atomic mass of a bit more than 12. Carbon is important to biology because of carbon's strong tendency to form pure covalent bonds. Thus carbon atoms provide the skeletal framework of the molecules found in living things. Naturally pure carbon is found in three forms; graphite, buckminsterfullerine and its variants, and diamonds. It might be some some interest to diamond purchasers to note that diamonds eventually will decay into graphite. 

Carboxyl. Refers to a functional group containing a carbon atom double bonded to an oxygen and single bonded to a hydroxyl(OH) group. Carboxyl groups are characteristic of organic acids and thus relate to the "acid" in the name amino acid.

Carcinogen. A chemical that causes cancer. Tars from cigarettes, benzene and various dyes are good examples.

Carpel. A leaf like section of a flower's female reproductive parts(Pistil) and that contains the ovules. Cut open a grapefruit. Each of the little sections is the remnant of a carpel.

Carrying capacity. In ecology, the number of individuals of a particular species that a region can sustain indefinitely. An important concept because humans may have exceeded the carrying capacity of this planet. 
Caste. Individual organisms in a social organization that have specialized functions. Castes may be temporal meaning that as the organism ages it takes on different sets of tasks within its group. Castes may also be based on morphology as in ants, bees and wasps where some species have highly specialized workers.

Catabolism. The set of metabolic reactions involved in taking complex molecules and breaking them down into simple molecules. Digestion is a set of reactions that is part of catabolism. Another example is breaking glucose down into carbon dioxide and water as part of cellular respiration.

Catalyst. A substance that speeds up a chemical reaction without being destroyed by that reaction. A real important concept in biology because without organic catalysts called enzymes, life could not exist at the temperatures that it does. 
Cell. In biology a structure surrounded by a membrane and containing genetic material(DNA) on the inside. These structures are capable of self maintenance, self replication, metabolism, homeostasis, and response to the environment. These structures are considered by most biologist to be the basic unit of life. 
Cell mediated immunity. The part of the immune system that largely involves defense of the body by responding to infected cells rather than by the production of antibodies. 
Cellulose. A polysaccharide made of repeating glucose subunits characterized by relative inability to dissolve in water. Cellulose makes up the cell walls of plants and many algae and is one of the most abundant organic compounds on the planet. Wood and cotton are examples of substances consisting of cellulose. 
Centriole. A cylindrical structure made from a series of 9 paired microtubules that is involved in organization of microskeletal elements in the cells of animals and some plants. The centriole found just beneath the surface of a eukaryote flagellum or cilium is called a basal body while the perpendicularly paired centrioles found near the nucleus during interphase of animal cells is sometimes called the central body(centrosome). The centriole is encountered during discussions of mitosis and meiosis. 
Centromere. A region on a chromosome where microtubules attach from the spindle during mitosis. Also serves as the point of attachment for the two chromatids in a duplicated chromosome. 
Chemical Bonds. An "attachment" between two or more atoms involving either a complete transfer of electrons(ionic bonds) or a sharing of electrons(covalent bonds). 
Chemoreceptor. A cell either on the surface of an animal or inside the animal that senses the presence or change in the concentration of certain molecules and relays that information to the the central nervous system. The human nose contains a sophisticated system of chemoreceptors.....abeit not a very sensitive one. 
Chemosynthetic autotroph(Chemoautotroph). An organism that obtains its energy from simple inorganic compounds such as sulfur compounds or nitrates.  

Chitin. A specialized polysaccharide containing nitrogen that occurs in the exoskeleton of insects and other arthropods. Chitin also makes up a large part of the cell walls in many fungi. 

Chlorophyll. Any of several green pigments, found in plants and most other photosynthetic autotrophs, the pigments all having a characteristic set of rings containing carbon and nitrogen along with a magnesium atom. Chlorophylls are important pigments in photosynthesis.

Chloroplast. A bacteria like green organelle in the cells of plants as well as in many protists. This organelle is the site of photosynthesis and gets its name from the presence of the green pigments, the chlorophylls. 
CHNOPS. An acronym for the most abundant elements in living things: Carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur.

Chromatid. A single molecule of DNA and associated proteins found as part of a duplicated(replicated) chromosome. 
Chromosome. A chromosome is one or two large DNA molecules and associated proteins that behave as a single unit in the cell.

Cilium. A short hair like structure on the surface of many cells. Cilia are typically much shorter than the length of the cells they are part of, and have a return and a power stroke involving the whole length of the structure. The plural of cilium is cilia. 
Cleavage. A chemical reaction in which a large molecule is broken apart into two or more subunits. Usually in biological systems the net effect is to add water to the molecules, hence this type of cleavage is called hydrolysis.

Clone. A group of cells or organisms that are derived by mitosis from another organism. Clones happen naturally as part of asexual reproduction in many organisms, but clones have become of some interest in biotechnology. 
Clonal selection. In the immune system the process by which only those cells able to produce an appropriate antibody to an antigen or otherwise respond in an appropriate manner to the antigen are stimulated to multiply. 
Codominance. A mode of inheritance in which the heterozygote has a phenotype that is different the phenotypes of either homozygotes. For instance for human blood type, if one homozygote is Type A, the other Type B, then the heterozygote will be Type AB. Codominance arises if both genes in the gene pair express a product. 
Codon. A triplet of three nucleotide bases in messenger RNA that relate to an amino acid in the translation part of protein synthesis or an instruction to stop translation. 
Coenzyme. A Non protein organic molecule that functions along with an enzyme to either activate or deactivate the enzyme. Organic cofactors. 
Coevolution. The idea that in a biological community, the adaptations that arise in different species are at least in part in response to selective pressures put on the species by each other. For example flowers and their pollinators coevolve with respect to each other. 
Cofactor. A chemical that works cooperatively with an enzyme to enhance the enzyme's catalytic ability. Cofactors maybe metallic ions or small organic molecules. 
Cohesive. The tendency of a substance to stick to itself or stick together. Water molecules tend to stick together, a property that is important for living things. 
Commensalism. A type of symbiosis in which one species benefits but the other species is neither harmed or benefited by the relationship. Certain mites that live in the skin of our faces are a good example. 
Community. In ecology..all the populations of all the species living a particular area.  

Compound. A compound is a molecule consisting of at least two different elements. For example the molecule carbon dioxide is a compound but oxygen gas is also a molecule but not a compound.

Concentration gradient. A change in the number of molecules of a particular substance per unit volume between two points. The steeper the concentration gradient the greater the difference in concentration between the two points. 

Condensation reaction. A type of chemical reaction in which two or more simple molecules are joined together to make a more complex molecule. In biology the most common type of condensation reaction takes place by effectively removing a water from two molecules being joined. This type of condensation reaction is called a dehydration synthesis.  

Conditioning. A change in the behavior of an animal based its ability to associate an environmental signal with some sort of positive or negative outcome. In classical conditioning the animal learns to associate an outcome with an environmental signal that normally is not associated with the outcome. For example, Pavlov's dogs learned to salivate upon hearing a bell that was rung whenever food was presented. In operant conditioning the organism provides its behaviors based on the results it obtains while manipulating its environment. Thus, caged pigeons can learn that pecking a certain red button will lead to the release of a food pellet or other reward. 

Conjugation. A process by which genetic material is exchanged between two cells through a bridge of cytoplasm that connects the cells. This happens in bacteria and in many protists. 
Consumer. A an organism that feeds on plants or other autotrophs or feeds on other consumers(e.g. a predator) 

Control group. In an experiment, a group of subjects that have all variables the same as those found in an experimental group except for just the variables being investigated in the experiment.

Cytokinesis. Cytokinesis or division of the cytoplasm is the distribution of the cytoplasm into two or more daughter cells that typically happens as part of cell reproduction. Note that cytokinesis is not part of either mitosis or meiosis proper.

Cytoplasm. The region of the cell that is between the nucleus and the cell membrane. In prokaryotes the region of the cell outside of the region where the DNA is located.