Biochemistry Glossary 1 C

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cAMP.

Back 1

3',5' cyclic adenosine monophosphate. The cAMP molecule plays a key role in metabolic regulation.

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CAP.

Back 2

The catabolite gene activator protein, sometimes incorrectly referred to as the CRP protein. The latter term, in small letters (crp), should be used to refer to the gene but not to the protein.

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Capping.

Back 3

Covalent modification involving the addition of a modified guanidine group in a 5'-5" linkage. It occurs only in eukaryotes, primarily on mRNA molecules.

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Carbohydrate.

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A polyhydroxy aldehyde or ketone.

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Carboxylic acid.

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A molecule containing a carbon atom attached to a hydroxyl group and to an oxygen atom by a double bond

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Carcinogen.

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A chemical that can cause cancer.

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Carotenoids.

Back 7

Lipid-soluble pigments that are made from isoprene units.

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Catabolism.

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That part of metabolism that is concerned with degradation reactions.

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Catabolite repression.

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The general repression of transcription of genes associated with catabolism that is seen in the presence of glucose.

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Catalyst.

Back 10

A compound that lowers the activation energy of a reaction without itself being consumed.

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Catalytic site.

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The site of an enzyme involved in the catalytic process.

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Catenane.

Back 12

An interlocked pair of circular structures, such as covalently closed DNA molecules.

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Catenation.

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The linking of molecules without any direct covalent bonding between them, as when two circular DNA molecules interlock like the links in a chain.

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cDNA.

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Complementary DNA, made in vitro from the mRNA by the enzyme reverse transcriptase using deoxyribonucleotide triphosphates. Unlike mRNA, cDNA can be easily propagated and sequenced.

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Cell commitment.

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That stage in a cell's life when it be comes committed to a certain line of development.

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Cell cycle.

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All of those stages that a cell passes through from one cell generation to the next.

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Cell line.

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An established clone originally derived from a whole organism through a long process of cultivation.

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Cell lineage.

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The pedigree of cells resulting from binary fission.

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Cell wall.

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A tough outer coating found in many plant, fungal, and bacterial cells that accounts for their ability to withstand mechanical stress or abrupt changes in osmotic pressure. Cell walls always contain a carbohydrate component and frequently also a peptide and a lipid component.

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Chelate.

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A molecule that contains more than one binding site and frequently binds to another molecule through more than one binding site at the same time.

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Chemiosmotic coupling.

Back 21

The coupling of ATP synthesis to an electrochemical potential gradient across a membrane.

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Chimeric DNA.

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Recombinant DNA whose components originate from two or more different sources.

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Chiral compound.

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A compound that can exist in two forms that are non-superimposable images of one another.

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Chlorophyll.

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A green photosynthetic pigment that is made of a magnesium dihydroporphyrin complex.

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Chloroplast.

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A chlorophyll-containing photosynthetic organelle, found in eukaryotic cells, that can harness light energy.

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Chromatin.

Back 26

The nucleoprotein fibers of eukaryotic chromosomes.

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Chromatography.

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A procedure for separating chemically similar molecules. Segregation is usually carried out on paper or in glass or metal columns with the help of different solvents. The paper or glass columns contain porous solids with functional groups that have limited affinities for the molecules being separated.

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Chromosome.

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A thread-like structure, visible in the cell nucleus during metaphase, that carries the hereditary information.

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Chromosome puff.

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A swollen region of a giant chromosome; the swelling reflects a high degree of transcription activity.

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Cis dominance.

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Property of a sequence or a gene that exerts a dominant effect on a gene to which it is linked.

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Cistron.

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A genetic unit that encodes a single polypeptide chain.

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Clone.

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One of a group of genetically identical cells or organisms derived from a common ancestor.

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Cloning vector.

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A self-replicating entity to which foreign DNA can be covalently attached for purposes of amplification in host cells.

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Coactivator.

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A molecule that functions together with a protein apoactivator. For example, cAMP is a coactivator of the CAP protein.

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Codon.

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In a messenger RNA molecule, a sequence of three bases that represents a particular amino acid.

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Coenzyme.

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An organic molecule that associates with enzymes and affects their activity.

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Cofactor.

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A small molecule required for enzyme activity. It could be organic in nature, like a coenzyme, or inorganic in nature, like a metallic cation.

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Complementary base sequence.

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For a given sequence of nucleic acids, the nucleic acids that are related to them by the rules of base pairing.

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Configuration.

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The spatial arrangement in which atoms are covalently linked in a molecule.

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Conformation.

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The three-dimensional arrangement adopted by a molecule, usually a complex macromolecule. Molecules with the same configuration can have more than one conformation.

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Consensus sequence.

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In nucleic acids, the "average" sequence that signals a certain type of action by a specific protein. The sequences actually observed usually vary around this average.

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Constitutive enzymes.

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Enzymes synthesized in fixed amounts, regardless of growth conditions.

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Cooperative binding.

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A situation in which the binding of one ligand to a macromolecule favors the binding of another. For example, DNA cooperatively binds histone molecules, and hemoglobin cooperatively binds oxygen molecules.

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Coordinate induction.

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The simultaneous expression of two or more genes.

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Cosmid.

Back 45

A DNA molecule with cos ends from lambda-bacteriophage that can be packaged in vitro into a virus for infection purposes .

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Cot curve.

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A curve that indicates the rate of DNA-DNA annealing as a function of DNA concentration and time.

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Cytidine.

Back 47

A pyrimidine nucleoside found in DNA and RNA.

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Cytochromes.

Back 48

Heme-containing proteins that function as electron carriers in oxidative phosphorylation and photosynthesis.

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Cytokinin.

Back 49

A plant hormone produced in root tissue.

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Cytoplasm.

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The contents enclosed by the plasma (or cytoplasmic) membrane, excluding the nucleus.

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Cytosine.

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A pyrimidine base found in DNA and RNA.

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Cytoskeleton.

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The filamentous skeleton, formed in the eukaryotic cytoplasm, that is largely responsible for controlling cell shape.

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Cytosol.

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The liquid portion of the cytoplasm, including the macromolecules but not including the larger structures like subcellular organelles or cytoskeleton.