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Glossary AMINO ACID Any of a group of organic acids that are the building blocks of proteins. B-CELL Subgroup of cells produced in the lymph system, re- sponsible for secreting circulating antibodies. CARCINOGENESIS Multistep process of abnormal cell growth culminating in cancer. CARCINOMA Malignant tumor derived from epithelial tissue (outermost covering or lining of all free surfaces of the body); may be composed of undifferentiated cells or may closely resemble normal tissue. CAROTENOIDS Fat-soluble, yellow-to-orange/red pigments uni- versally present in the photosynthetic tissues of algae, pho- tosynthesizing bacteria, and eukaryoticâcontaining cells with a well-defined nucleusâplants; believed to be anti- carcinogenic either in themselves or through their conver- sion product, vitamin A. CELL LINE A mass of genetically identical cells grown from an originating cell in a culture medium under laboratory con- ditions. 117
GLOSSARY CODON The basic unit of the genetic code. Each codon, a se- quence of three nucleotide bases in a gene, is translated into one amino acid during protein biosynthesis. CRUCIFEROUS VEGETABLES Members of the mustard family (Cruciferae), including broccoli, cabbage, cauliflower, brussels sprouts, kohlrabi, and turnips; in their raw form believed to protect against colorectal cancer. GENOME An organism's entire complement of DNA, which de- termines its genetic makeup. INITIATION The first step of carcinogenesis; takes place at the molecular level. LEUKEMIA Any one of a complex of malignant diseases, chronic or acute, marked by an excess number of one of the types of white blood cells (leukocytes): lymphocytes, produced in the lymph nodes and spleen; granulocytes, produced in the bone marrow; or monocytes, produced in the connec- tive tissue. LYMPHOMA Malignant growth of lymphocytes. Abnormal cells may disseminate in the blood or remain localized in lymph nodes. METASTASIS The spread of individual cancerous cells of a tumor from their primary site. Metastasized cells may remain dis- seminated (as in leukemia and some lymphomas) or colo- nize into new tumors. MITOSIS The process by which the nucleus of a cell (in which the DNA has replicated itself) divides, such that two daugh- ter cells are produced with the same number of chromo- somes as the parent cells. MONOCLONAL ANTIBODIES Highly specific and pure antibodies, obtained through the use of recombinant DNA technology, that attach to individual sites on the surface of a protein. MUTAGEN A physical or chemical agent capable of inducing a mutation. MUTATION In genetics and molecular biology: a sudden change, either in the base sequence of DNA or in the order, number, or placement of genes on or across chromosomes, that may result in a change in the structure or function of a protein. 118
GLOSSARY NEUROBLASTOMA Malignant tumor characterized by immature, only slightly differentiated nerve cells of embyronic type. NUCLEOTIDE Subunit of DNA or RNA consisting of a sugar molecule, a phosphate molecule, and one of four possible base molecules: adenine, thymine, guanine, or cytosine (in RNA another base, uracil, is found instead of thymine). POINT MUTATION Change in a single nucleotide base, which can alter the message of a codon. This in turn can cause a change in the order of assembled amino acids, resulting in synthesis of an altered or completely different protein. PROMOTER In carcinogenesis: a chemical that increases the car- cinogenic activity of other agents that initiate carcinogen- esis. In genetics: a region of DNA that is the initial binding site for the enzyme that will transcribe a gene into RNA. PSYCHOTROPIC DRUG Any of a broad category of drugs, the primary action of which causes a marked and usually pre- dictable change in mental state; includes tranquilizers, stim- ulants, antidepressants, barbiturates, and hallucinogens. RECOMBINANT DNA TECHNOLOGY The methodology and tech- niques involved in forming hybrid molecules under labo- ratory conditions by splicing segments of DNA and re- joining them in a novel arrangement. REPLICATION Refers to both self-synthesis of DNA and synthesis of RNA by DNA. In the latter case, single-stranded DNA serves as a template for RNA. DNA reproduces itself by separating into two strands, each of which then synthesizes a complement of itself. RETROVIRUS Any of a class of viruses the genetic material of which is RNA instead of DNA. All viruses must use the genetic machinery of a host cell to reproduce themselves, but retroviruses undergo an extra step in which RNA is copied into DNA. SARCOMA Malignant tumor, poorly differentiated, derived from connective tissue such as blood, bone, and cartilage. TERATOGEN A physical or chemical agent that causes a birth defect. TRANSCRIPTION The first step of protein biosynthesis, in which DNA directs the production of RNA. 119
GLOSSARY TRANSLATION The second step of protein biosynthesis, in which RNA directs the assembling of amino acids to form the primary structures of proteins. TRANSLOCATION Movement of a gene or genes from one chro- mosome to another (includes the exchange of genes be- tween chromosomes). TUMORIGENESIS The induction of a benign or malignant growth of abnormal cells. 120