An
official FDA communication that informs an NDA or BLA sponsor of a
decision by the agency. An approval letter allows commercial marketing
of the product.
Active immunity
A type
of acquired immunity whereby resistance to a disease is built up by
either having the disease or receiving a vaccine to it.
Adjuvant
Insoluble material that increases the formation and persistence of antibodies when injected with an antigen.
Aerobic
Needing oxygen for growth.
Agrobacterium tumefaciens
A common soil bacterium used as a vector to create transgenic plants.
Allele
Any of several alternative forms of a gene.
Allogenic
Of the same species, but with a different genotype. Also allogeneic.
Alzheimer's disease
A
disease characterized by, among other things, progressive loss of
memory. The development of Alzheimer's disease is thought to be
associated, in part, with possessing certain alleles of the gene that
encodes apolipoprotein E.
Amino acids
Building
blocks of proteins. There are 20 common amino acids: alanine, arginine,
aspargine, aspartic acid, cysteine, glutamic acid, glutamine, glycine,
histidine, isoleucine, leucine, lysine, methionine, phenylalanine,
proline, serine, threonine, tryptophan, tyrosine and valine. Two more
amino acids have been discovered in microbes: selenocysteine and
pyrrolysine.
Amplification
The process of increasing the number of copies of a particular gene or chromosomal sequence.
Anaerobic
Growing in the absence of oxygen.
Antibiotic
Chemical
substance formed as a metabolic byproduct in bacteria or fungi and used
to treat bacterial infections. Antibiotics can be produced naturally,
using microorganisms, or synthetically.
Antibody
Protein produced by humans and higher animals in response to the presence of a specific antigen.
Anticodon
Triplet
of nucleotide bases (codon) in transfer RNA that pairs with (is
complementary to) a triplet in messenger RNA. For example, if the codon
is UCG, the anticodon is AGC. See also Base; Base pair;
Complementarity.
Antigen
A substance that, when introduced into the body, induces an immune response by a specific antibody.
Antigenic determinant
See Hapten.
Antihemophilic factors
A
family of whole-blood proteins that initiate blood clotting. Some of
these proteins, such as factor VIII, can be used to treat hemophilia.
See also Factor VIII; Kidney plasminogen activator.
Antisense
A
piece of DNA producing a mirror image ("antisense") messenger RNA that
is opposite in sequence to one directing protein synthesis. Antisense
technology is used to selectively turn off production of certain
proteins.
Antiserum
Blood serum containing specific antibodies against an antigen. Antisera are used to confer passive immunity to many diseases.
Apolipoprotein E (Apo E)
Certain
alleles of the gene that encodes the protein apolipoprotein E have been
associated with the development of heart disease and Alzheimer's
disease.
Assay
Technique for measuring a biological response.
Attenuated
Weakened; with reference to vaccines, made from pathogenic organisms that have been treated so as to render them avirulent.
Autoimmune disease
A disease in which the body produces antibodies against its own tissues.
Autoimmunity
A condition in which the body mounts an immune response against one of its own organs or tissues.
Autosome
Any chromosome other than a sex chromosome.
Avirulent
Unable to cause disease.
B
Bacillus subtilis
A bacterium commonly used as a host in recombinant DNA experiments. Important because of its ability to secrete proteins.
Bacillus thuringiensis (Bt)
Naturally
occurring soil bacterium that generates a protein toxic to a variety of
lepidoptera, such as corn borers, but is harmless to people and
animals.
Bacteriophage
Virus that lives in and kills bacteria. Also called phage.
Bacterium
Any
of a large group of microscopic organisms with a very simple cell
structure. Some manufacture their own food, some live as parasites on
other organisms, and some live on decaying matter.
Base
A
key component of DNA and RNA molecules. Four different bases are found
in DNA: adenine (A), cytosine (C), guanine (G) and thymine (T). In RNA,
uracil (U) substitutes for thymine. Also known as nitrogenous bases. A
base, a phosphate molecule and a sugar joined together constitute a
nucleotide.
Base pair
Two nucleotide
bases on different strands of the nucleic acid molecule that bond
together. The bases can pair in only one way: adenine with thymine
(DNA), or uracil (RNA) and guanine with cytosine.
Bioassay
Determination
of the effectiveness of a compound by measuring its effect on animals,
tissues or organisms in comparison with a standard preparation.
Bioaugmentation
Increasing
the activity of bacteria that break down pollutants by adding more of
their kind. A technique used in bioremediation.
Biocatalyst
In bioprocessing, an enzyme that activates or speeds up a biochemical reaction.
Biochemical
The product of a chemical reaction in a living organism.
Biochip
An electronic device that uses organic molecules to form a semiconductor.
Bioconversion
Chemical restructuring of raw materials by using a biocatalyst.
Biodegradable
Capable of being reduced to water and carbon dioxide by the action of microorganisms.
Bioenrichment
A
bioremediation strategy that involves adding nutrients or oxygen,
thereby bolstering the activity of microbes as they break down
pollutants.
Bioinformatics
The science
of informatics as applied to biological research. Informatics is the
management and analysis of data using advanced computing techniques.
Bioinformatics is particularly important as an adjunct to genomics
research, because of the large amount of complex data this research
generates.
Biolistic device
A device that shoots microscopic DNA-coated particles into target cells.
Biological oxygen demand (BOD)
The amount of oxygen used for growth by organisms in water that contains organic matter.
Biologic
A
therapeutic or prophylactic derived from a living source (human, animal
or unicellular). Most biologics are complex mixtures that are not
easily identified or characterized, and many are manufactured using
biotechnology. Biological products often represent the cutting-edge of
biomedical research and are sometimes the most effective way to prevent
or treat a disease.
Biologic response modifier
A
substance that alters the growth or functioning of a cell. Includes
hormones and compounds that affect the nervous and immune systems.
Biomass
The
totality of biological matter in a given area. As commonly used in
biotechnology, refers to the use of cellulose, a renewable resource,
for the production of chemicals that can be used to generate energy or
as alternative feedstocks for the chemical industry to reduce
dependence on nonrenewable fossil fuels.
Biomaterials
Biological
molecules, such as proteins and complex sugars, used to make medical
devices, including structural elements used in reconstructive surgery.
Bioprocess
A process in which living cells, or components thereof, are used to produce a desired product.
Bioreactor
Vessel used for bioprocessing.
Bioremediation
The use of microorganisms to remedy environmental problems, rendering hazardous wastes nonhazardous.
Biosynthesis
Production of a chemical by a living organism.
Biotechnology
The use of biological processes to solve problems or make useful products.
Biotransformation
The use of enzymes in chemical synthesis to produce chemical compounds of a desired stereochemistry.
Blastocyst (Blastula)
The
4- to 5-day-old ball of undifferentiated cells from which a prospective
embryo develops. In mammals it consists of two distinct parts: the
inner cell mass and the trophoblast.
B lymphocytes (B-cells)
A class of lymphocytes, released from the bone marrow, that produce antibodies.
Bovine somatotropin (BST)
A
hormone secreted by the bovine pituitary gland. It is used to increase
milk production by improving the feed efficiency in dairy cattle milk.
Also called bovine growth hormone.
BRCA1 and BRCA2
(BReast
CAncer genes 1 and 2) Two genes that normally help to restrain cell
growth, but which can contain certain genetic mutations associated with
the development of breast and ovarian cancer. Note, however, that
inherited BRCA1 and BRCA2 mutations are thought to account for less
than 10 percent of all breast and ovarian cancers. Recent evidence
suggests that somatic cell genetic mutations (i.e., noninherited
genetic mutations) in these two genes may also play a role in the
development of cancer.
C
Callus
A cluster of undifferentiated plant cells that can, in some species, be induced to form the whole plant.
Carbohydrate
A type of biological molecule composed of simple sugars such as glucose. Common examples include starch and cellulose.
Carcinogen
Cancer-causing agent.
Catalyst
An agent (such as an enzyme or a metallic complex) that facilitates a reaction but is not itself changed during the reaction.
Cell
The smallest structural unit of a living organism that can grow and reproduce independently.
Cell culture
Growth of cells under laboratory conditions.
Cell differentiation
The process by which descendants of a common parental cell achieve specialized structure and function
Cell fusion
See Fusion.
Cell line
Cells that grow and replicate continuously outside the living organism.
Cell-mediated immunity
Acquired
immunity in which T lymphocytes play a predominant role. Development of
the thymus in early life is critical to the proper development and
functioning of cell-mediated immunity.
Chemical genomics
Using
structural and functional genomic information about biological
molecules, especially proteins, to identify useful small molecules and
alter their structure to improve their efficacy.
Chimera
The
individual (animal or lower organism) produced by grafting an embryonic
part of one individual onto an embryo of either the same or a different
species.
Chromosomes
Threadlike components in the cell that contain DNA and proteins. Genes are carried on the chromosomes.
Clinical studies
Human
studies that are designed to measure the efficacy of a new drug or
biologic. Clinical studies routinely involve the use of a control group
of pati
ents that is given an inactive substance (placebo) that looks like the test product.
Clone
A
term that is applied to genes, cells or entire organisms that are
derived from—and are genetically identical to—a single common ancestor
gene, cell or organism, respectively. Cloning of genes and cells to
create many copies in the laboratory is a common procedure essential
for biomedical research. Note that several processes commonly described
as cell "cloning" give rise to cells that are almost but not completely
genetically identical to the ancestor cell. Cloning of organisms from
embryonic cells occurs naturally in nature (e.g., identical twins).
Researchers have achieved laboratory cloning using genetic material
from adult animals of several species, including mice, pigs and sheep.
Codon
A sequence of three nucleotide bases that specifies an amino acid or represents a signal to stop or start a function.
Co-enzyme
An
organic compound that is necessary for the functioning of an enzyme.
Co-enzymes are smaller than the enzymes themselves and sometimes
separable from them.
Co-factor
A nonprotein substance required for certain enzymes to function. Co-factors can be co-enzymes or metallic ions.
Colony-stimulating factors (CSFs)
A
group of lymphokines that induce the maturation and proliferation of
white blood cells from the primitive cell types present in bone marrow.
Combinatorial chemistry
A product
discovery technique that uses robotics and parallel synthesis to
generate and screen quickly as many as several million molecules with
similar structure in order to find chemical molecules with desired
properties.
Co-metabolism
A microbe oxidizing not only its main energy source but also another organic compound.
Complementarity
The
relationship of the nucleotide bases on two different strands of DNA or
RNA. When the bases are paired properly (adenine with thymine [DNA] or
uracil [RNA]; guanine with cytosine), the strands are complementary.
Complementary DNA (cDNA)
DNA
synthesized from a messenger RNA rather than from a DNA template. This
type of DNA is used for cloning or as a DNA probe for locating specific
genes in DNA hybridization studies.
Computational biology
A subdiscipline within bioinformatics concerned with computation-based
research devoted to understanding basic biological processes.
Conjugation
Sexual reproduction of bacterial cells in which there is a one-way exchange of genetic material between the cells in contact.
Crossing over
Exchange of genes between two paired chromosomes.
Cross-licensing
Legal,
contractual procedure in which two or more firms with competing,
similar technologies and possible conflicting patent claims strike a
deal to reduce the need for legal actions to clarify who is to profit
from applications of the technology.
Culture
As a noun, cultivation of living organisms in prepared medium; as a verb, to grow in prepared medium.
Culture medium
Any
nutrient system for the artificial cultivation of bacteria or other
cells; usually a complex mixture of organic and inorganic materials.
Cyto-
Referring to cell.
Cytogenetics
Study of the cell and its heredity-related components, especially chromosomes.
Cytoplasm
Cellular material that is within the cell membrane and surrounds the nucleus.
Cytotoxic
Able to cause cell death.
D
Deoxyribonucleic acid (DNA)
The
molecule that carries the genetic information for most living systems.
The DNA molecule consists of four bases (adenine, cytosine, guanine and
thymine) and a sugar-phosphate backbone, arranged in two connected
strands to form a double helix. See also Complementary DNA; Double
helix; Recombinant DNA.
Differentiation
The process of biochemical and structural changes by which cells become specialized in form and function.
Diploid
A cell with two complete sets of chromosomes. Compare Haploid.
DNA
See Deoxyribonucleic acid.
DNA chip
A small piece of glass or silicon that has small pieces of DNA arrayed on its surface.
DNA fingerprinting
The
use of restriction enzymes to measure the genetic variation of
individuals. This technology is often used as a forensic tool to detect
differences or similarities in blood and tissue samples at crime
scenes.
DNA hybridization
The formation
of a double-stranded nucleic acid molecule from two separate strands.
The term also applies to a molecular technique that uses one nucleic
acid strand to locate another.
DNA library
A collection of cloned DNA fragments that collectively represent the genome of an organism.
DNA polymerase
An enzyme that replicates DNA. DNA polymerase is the basis of PCR—the polymerase chain reaction.
DNA probe
A
small piece of nucleic acid that has been labeled with a radioactive
isotope, dye or enzyme and is used to locate a particular nucleotide
sequence or gene on a DNA molecule.
DNA repair enzymes
Proteins that recognize and repair certain abnormalities in DNA.
DNA sequence
The order of nucleotide bases in the DNA molecule.
DNA vaccines
Pieces of foreign DNA that are injected into an organism to trigger an immune response.
Double helix
A
term often used to describe the configuration of the DNA molecule. The
helix consists of two spiraling strands of nucleotides (a sugar,
phosphate and base) joined crosswise by specific pairing of the bases.
See also Deoxyribonucleic acid; Base; Base pair.
Diagnostic
A
product used for the diagnosis of disease or medical condition. Both
monoclonal antibodies and DNA probes are useful diagnostic products.
Drug delivery
The
process by which a formulated drug is administered to the patient.
Traditional routes have been oral or intravenous perfusion. New methods
deliver through the skin with a transdermal patch or across the nasal
membrane with an aerosol spray.
E
Electrophoresis
A technique for separating different types of molecules based on their patterns of movement in an electrical field.
Electroporation
The
creation of reversible small holes in a cell wall or membrane through
which foreign DNA can pass. This DNA can then integrate into the cell's
genome.
Enzyme-linked immunosorbent assay (ELISA)
A technique for detecting specific proteins by using antibodies linked to enzymes.
Embryonic stem cells
Cells
that can give rise to any type of differentiated cell. They can be
derived from two sources: the inner cell mass from a blastocyst or the
primordial germ cells (eggs and sperm) of an older embryo.
Endostatin
An endogenous protein that blocks the proliferation of blood vessels.
Enzyme
A protein catalyst that facilitates specific chemical or metabolic reactions necessary for cell growth and reproduction.
Erythropoietin (EPO)
A protein that boosts production of red blood cells. It is clinically useful in treating certain types of anemia.
Escherichia coli (E. coli)
A
bacterium that inhabits the intestinal tract of most vertebrates. Much
of the work using recombinant DNA techniques has been carried out with
this organism because it has been genetically well characterized.
Eukaryote
A
cell or organism containing a true nucleus, with a well-defined
membrane surrounding the nucleus. All organisms except bacteria,
viruses and cyanobacteria are eukaryotic. Compare Prokaryote.
Exon
In
eukaryotic cells, that part of the gene that is transcribed into
messenger RNA and encodes a protein. See also Intron; Splicing.
Expression
In
genetics, manifestation of a characteristic that is specified by a
gene. With hereditary disease, for example, a person can carry the gene
for the disease but not actually have the disease. In this case, the
gene is present but not expressed. In industrial biotechnology, the
term is often used to mean the production of a protein by a gene that
has been inserted into a new host organism.
Extremophiles
Microorganisms that live at extreme levels of pH, temperature, pressure and salinity.
F
Factor VIII
A large, complex protein that aids in blood clotting and is used to treat hemophilia. See also Antihemophilic factors.
Feedstock
The raw material used for chemical or biological processes.
Fermentation
The
process of growing microorganisms for the production of various
chemical or pharmaceutical compounds. Microbes are normally incubated
under specific conditions in the presence of nutrients in large tanks
called fermentors.
Functional foods
Foods
containing compounds with beneficial health effects beyond those
provided by the basic nutrients, minerals and vitamins. Also called
nutraceuticals.
Functional genomics
A field of research that aims to understand what each gene does, how it is regulated and how it interacts with other genes.
Fusion
Joining
of the membrane of two cells, thus creating a daughter cell that
contains some of the same properties from each parent cells. Used in
making hybridomas.
G
Gel electrophoresis
A process for separating molecules by forcing them to migrate through a gel under the influence of an electric field.
Gene
A
segment of chromosome. Some genes direct the syntheses of proteins,
while others have regulatory functions. See also Operator gene;
Structural gene; Suppressor gene.
Gene amplification
The increase, within a cell, of the number of copies of a given gene.
Gene knockout
The replacement of a normal gene with a mutated form of the gene by using homologous recombination. Used to study gene function.
Gene machine
A computerized device for synthesizing genes by combing nucleotides (bases) in the proper order.
Gene mapping
Determination of the relative locations of genes on a chromosome.
Gene sequencing
Determination of the sequence of nucleotide bases in a strand of DNA. See also Sequencing.
Gene therapy
The
replacement of a defective gene in an organism suffering from a genetic
disease. Recombinant DNA techniques are used to isolate the functioning
gene and insert it into cells. More than 300 single-gene genetic
disorders have been identified in humans. A significant percentage of
these may be amenable to gene therapy.
Genetic code
The
code by which genetic information in DNA is translated into biological
function. A set of three nucleotides (codons), the building blocks of
DNA, signifies one amino acid, the building blocks of proteins.
Genetic modification
A
number of techniques, such as selective breeding, mutagenesis,
transposon insertions and recombinant DNA technology, that are used to
alter the genetic material of cells in order to make them capable of
producing new substances, performing new functions or blocking the
production of substances.
Genetic predisposition
Susceptibility
to disease that is related to a genetic predisposition mutation, which
may or may not result in actual development of the disease.
Genetic screening
The
use of a specific biological test to screen for inherited diseases or
medical conditions. Testing can be conducted prenatally to check for
metabolic defects and congenital disorders in the developing fetus as
well as postnatally to screen for carriers of heritable diseases.
Genetic testing
The
analysis of an individual's genetic material. Genetic testing can be
used to gather information on an individual's genetic predisposition to
a particular health condition, or to confirm a diagnosis of genetic
disease.
Genome
The total hereditary material of a cell, comprising the entire chromosomal set found in each nucleus of a given species.
Genomics
The
study of genes and their function. Recent advances in genomics are
bringing about a revolution in our understanding of the molecular
mechanisms of disease, including the complex interplay of genetic and
environmental factors. Genomics is also stimulating the discovery of
breakthrough health-care products by revealing thousands of new
biological targets for the development of drugs and by giving
scientists innovative ways to design new drugs, vaccines and DNA
diagnostics. Genomic-based therapeutics may include "traditional" small
chemical drugs, as well as protein drugs and gene therapy.
Genotype
Genetic makeup of an individual or group. Compare Phenotype.
Germ cell
Reproductive cell (sperm or egg). Also called gamete or sex cell.
Germplasm
The total genetic variability, represented by germ cells or seeds, available to a particular population of organisms.
Glycoprotein
A protein conjugated with a carbohydrate group.
Granulocyte
One of three types of white blood cells. Granulocytes digest bacteria and other parasites.
A
natural hormone that stimulates white blood cell production,
particularly that of granulocytes and monocytes (the precursors of
macrophages).
Growth factors
Naturally
occurring proteins that stimulate the growth and reproduction of
specific cell types. Growth factors are essential to regenerative
medicine and tissue engineering.
Growth hormone
A
protein produced by the pituitary gland that is involved in cell
growth. Human growth hormone is used clinically to treat dwarfism.
Various animal growth hormones can be used to improve milk production
as well as produce a leaner variety of meat.
H
Haploid
A cell with half the usual number of chromosomes, or only one chromosome set. Sex cells are haploid. Compare Diploid.
Hapten
The
portion of an antigen that determines its immunological specificity.
When coupled to a large protein, a hapten stimulates the formation of
antibodies to the two-molecule complex. Also called antigenic
determinant.
Hemagglutination
Clumping (agglutination) of red blood cells.
Heredity
Transfer of genetic information from parent cells to progeny.
Histocompatibility
Immunologic similarity of tissues such that grafting can be done without tissue rejection.
Histocompatibility antigen
An antigen that causes the rejection of grafted material from an animal different in genotype from the host animal.
Homeobox
Family of genes that regulate activities of other genes (turns genes on and off).
Homologous
Corresponding or alike in structure, position or origin.
Hormone
A
chemical or protein that acts as a messenger or stimulatory signal,
relaying instructions to stop or start certain physiological
activities. Hormones are synthesized in one type of cell and then
released to direct the function of other cell types.
Host
A
cell or organism used for growth of a virus, plasmid or other form of
foreign DNA, or for the production of cloned substances.
Host-vector system
Combination of DNA-receiving cells (host) and DNA-transporting substance (vector) used for introducing foreign DNA into a cell.
Human Genome Project
An
international research effort aimed at discovering the full sequence of
bases in the human genome. Led in the United States by the National
Institutes of Health and the Department of Energy.
Human immunodeficiency virus (HIV)
The virus that causes acquired immune deficiency syndrome (AIDS).
Hybridization
Production
of offspring, or hybrids, from genetically dissimilar parents. The
process can be used to produce hybrid plants (by crossbreeding two
different varieties) or hybridomas (hybrid cells formed by fusing two
unlike cells, used in producing monoclonal antibodies). See DNA
hybridization.
Hybridoma
The cell
produced by fusing two cells of different origin. In monoclonal
antibody technology, hybridomas are formed by fusing an immortal cell
(one that divides continuously) and an antibody-producing cell. See
also Monoclonal antibody; Myeloma.
I
Immune response
The response of the immune system to challenge by a foreign antigen.
Immune serum
Blood serum containing antibodies.
Immune system
The
combination of cells, biological substances (such as antibodies) and
cellular activities that work together to provide resistance to
disease.
Immunity
Nonsusceptibility to
a disease or to the toxic effects of antigenic material. See also
Active immunity; Cell-mediated immunity; Natural active immunity;
Natural passive immunity; Passive immunity.
Immunoassay
Technique for identifying substances based on the use of antibodies.
Immunodiagnostic
The
use of specific antibodies to measure a substance. This tool is useful
in diagnosing infectious diseases and the presence of foreign
substances in a variety of human and animal fluids (blood, urine,
etc.). The approach is currently being investigated as a way of
locating tumor cells in the body.
Immunofluorescence
Technique
for identifying antigenic material that uses an antibody labeled with
fluorescent material. Specific binding of the antibody and antigen can
be seen under a microscope by applying ultraviolet light rays and
noting the visible light that is produced.
Immunogen
Any substance that can elicit an immune response.
Immunoglobulin
General
name for proteins that function as antibodies. These proteins differ
somewhat in structure and are grouped into five categories on the basis
of these differences; immunoglobulin G (IgG), IgM, IgA, IgE and IgD.
Immunology
Study of all phenomena related to the body's response to antigenic challenge (i.e., immunity, sensitivity and allergy).
Immunomodulators
A
diverse class of proteins that boost the immune system. Many are cell
growth factors that accelerate the production of specific cells that
are important in mounting an immune response in the body. These
proteins are being investigated for use in possible treatments for
cancer.
Immunotoxins
Specific
monoclonal antibodies that have a protein toxin molecule attached. The
monoclonal antibody is targeted against a tumor cell, and the toxin is
designed to kill that cell when the antibody binds to it.
Inducer
A
molecule or substance that increases the rate of enzyme synthesis,
usually by blocking the action of the corresponding repressor.
In situ
In its original or natural place or position.
Interferon
A
class of lymphokine proteins important in the immune response. There
are three major types of interferon: alpha (leukocyte), beta
(fibroblast) and gamma (immune). Interferons inhibit viral infections
and may have anticancer properties.
Interleukin
A
type of lymphokine that regulates the growth and development of white
blood cells. Twelve interleukins (IL-1 through IL-12) have been
identified to date.
Intron
In
eukaryotic cells, a sequence of DNA that is contained in the gene but
does not encode for protein. The presence of introns "splits" the
coding region of the gene into segments called exons. See also Exon;
Splicing.
Investigational New Drug Application (IND)
An
application to begin studies of a new drug or biologic on humans. The
IND gives the plan for the study and contains formulation,
manufacturing and animal test result information.
In vitro
Literally, "in glass." Performed in a test tube or other laboratory apparatus.
In vivo
In a living organism.
Islet cells
Pancreatic cells that are the source of insulin and two other hormones involved in regulating glucose metabolism and absorption.
Isoenzyme
One
of the several forms that a given enzyme can take. The forms may differ
in certain physical properties, but function similarly as biocatalysts.
Isogenic
Of the same genotype.
K
Kidney plasminogen activator
A precursor to the enzyme urokinase, which has blood-clotting properties.
L
Leukocyte
A
colorless cell in the blood, lymph and tissues that is an important
component of the body's immune system. Also called white blood cell.
Library
A set of cloned DNA fragments that taken collectively contain the entire genome of an organism. Also called a DNA library.
Ligase
An enzyme used to join DNA or RNA segments together.
Linkage
The tendency for certain genes to be inherited together due to their physical proximity on the chromosome.
Linker
A fragment of DNA with a restriction site that can be used to join DNA strands.
Lipoproteins
A
class of serum proteins that transport lipids and cholesterol in the
bloodstream. Abnormalities in lipoprotein metabolism have been
implicated in certain heart diseases.
Lymphocyte
A
type of leukocyte found in lymphatic tissue in the blood, lymph nodes
and organs. Lymphocytes are continuously made in the bone marrow and
mature into antibody-forming cells. See also B lymphocytes; T
lymphocytes.
Lymphokine
A class of
soluble proteins produced by white blood cells that play a role, as yet
not fully understood, in the immune response. See also Interferon;
Interleukin.
Lymphoma
Form of cancer that affects the lymph tissue.
M
Macrophage
A type
of white blood cell produced in blood vessels and loose connective
tissues that can ingest dead tissues and cells and is involved in
producing interleukin-1. When exposed to the lymphokine
macrophage-activating factor, macrophages also kill tumor cells. See
also Phagocyte.
Macrophage colony stimulating factor (M-CSF)
A natural hormone that stimulates the production of white blood cells, particularly monocytes (the precursors of macrophages).
Medium
A substance containing nutrients needed for cell growth.
Meiosis
Process
of cell reproduction whereby the daughter cells have half the
chromosome number of the parent cells. Sex cells are formed by meiosis.
Compare Mitosis.
Messenger RNA (mRNA)
Nucleic acid that carries instructions to a ribosome for the synthesis of a particular protein.
Metabolism
All biochemical activities carried out by an organism to maintain life.
Microbial herbicides and pesticides
Microorganisms
that are toxic to specific plants or insects. Because of their narrow
host range and limited toxicity, these microorganisms may be preferable
to their chemical counterparts for certain pest-control applications.
Microbiology
Study of living organisms that can be seen only under a microscope.
Microinjection
The injection of DNA using a very fine needle into a cell.
Microorganism
Any organism that can be seen only with the aid of a microscope. Also called microbe.
Mitosis
Process
of cell reproduction whereby the daughter cells are identical in
chromosome number to the parent cells. Compare Meiosis.
Molecular genetics
Study of how genes function to control cellular activities.
Monoclonal antibody (MAb)
Highly
specific, purified antibody that is derived from only one clone of
cells and recognizes only one antigen. See also Hybridoma; Myeloma.
Monocytes
One of three types of white blood cells. Monocytes are precursors to macrophages.
Multigenic
Of hereditary characteristics, one that is specified by several genes.
Mutagen
A substance that induces mutations.
Mutant
A cell that manifests new characteristics due to a change in its DNA.
Mutation
A change in the genetic material of a cell.
Myeloma
A type of cancer cell (plasma cell) that is used in monoclonal antibody technology to form hybridomas.
N
Natural active immunity
Immunity that is established after the occurrence of a disease.
Natural killer (NK) cell
A
type of leukocyte that attacks cancerous or virus-infected cells
without previous exposure to the antigen. NK cell activity is
stimulated by interferon.
Natural passive immunity
Immunity conferred by the mother on the fetus or newborn.
Nitrogen fixation
A
biological process (usually associated with plants) whereby certain
bacteria convert nitrogen in the air to ammonia, thus forming a
nutrient essential for plant growth.
Nitrogenous base
See Base.
Noncoding DNA
DNA that does not encode any product (RNA or protein). The majority of the DNA in plants and animals is noncoding.
Nuclease
An enzyme that, by cleaving chemical bonds, breaks down nucleic acids into their constituent nucleotides.
Nucleic acids
Large
molecules, generally found in the cell's nucleus and/or cytoplasm, that
are made up of nucleotides. The two most common nucleic acids are DNA
and RNA.
Nucleotides
The building
blocks of nucleic acids. Each nucleotide is composed of sugar,
phosphate and one of four nitrogen bases. The sugar in DNA is
deoxyribose and RNA's sugar is ribose. The sequence of the bases within
the nucleic acid determines the sequence of amino acids in a protein.
See also Base.
Nucleus
The structure within eukaryotic cells that contains chromosomal DNA.
O
Oligonucleotide
A polymer consisting of a small number (about two to 10) of nucleotides.
Oncogene
Gene thought to be capable of producing cancer.
Oncogenic
Cancer causing.
Oncology
Study of cancer.
Operator gene
A region of the chromosome, adjacent to the operon, where a repressor protein binds to prevent transcription of the operon.
Operon
Sequence
of genes responsible for synthesizing the enzymes needed for
biosynthesis of a molecule. An operon is controlled by an operator gene
and a repressor gene.
Organic compound
A compound containing carbon.
P
Passive immunity
Immunity acquired from receiving preformed antibodies.
Pathogen
Disease-causing organism.
Peptide
Two or more amino acids joined by a linkage called a peptide bond.
Phagocyte
A type of white blood cell that can ingest invading microorganisms and other foreign material. See also Macrophage.
Phenotype
Observable
characteristics resulting from interaction between an organism's
genetic makeup and the environment. Compare Genotype.
Photosynthesis
Conversion by plants of light energy into chemical energy, which is then used to support the plants' biological processes.
Phytoremediation
The use of plants to clean up pollution.
Plasma
The fluid (noncellular) fraction of blood.
Plasmapheresis
A technique used to separate useful factors from blood.
Plasmid
A small circular form of DNA that carries certain genes and is capable of replicating independently in a host cell.
Pluripotent cells
Having
the capacity to become any kind of cell or tissue in the body.
Embryonic stem cells and cells of the inner cell mass are pluripotent.
Adult stem cells are multipotent. The mammalian embryo (blastocyst
trophoblast plus inner cell mass) is totipotent because it can become
an entire organism. Fully differentiated cells from many plants are
totipotent.
Polyclonal
Derived from different types of cells.
Polymer
A long molecule of repeated subunits.
Polymerase
General term for enzymes that carry out the synthesis of nucleic acids.
Polymerase chain reaction (PCR)
A technique to amplify a target DNA sequence of nucleotides by several hundred thousandfold.
Polypeptide
Long chain of amino acids joined by peptide bonds.
Preclinical studies
Studies
that test a drug on animals and in other nonhuman test systems. Safety
information from such studies is used to support an investigational new
drug application (IND).
Prokaryote
An organism (e.g., bacterium, virus, cyanobacterium) whose DNA is not enclosed within a nuclear membrane. Compare Eukaryote.
Promoter
A
DNA sequence that is located in front of a gene and controls gene
expression. Promoters are required for binding of RNA polymerase to
initiate transcription.
Prophage
Phage nucleic acid that is incorporated into the host's chromosome but does not cause cell lysis.
Protein
A
molecule composed of amino acids. There are many types of proteins, all
carrying out different functions essential for cell growth.
Protein A
A protein produced by the bacterium Staphylococcus aureus that specifically binds antibodies. It is useful in the purification of monoclonal antibodies.
Proteomics
Each
cell produces thousands of proteins, each with a specific function.
This collection of proteins in a cell is known as the proteome, and,
unlike the genome, which is constant irrespective of cell type, the
proteome varies from one cell type to the next. The science of
proteomics attempts to identify the protein profile of each cell type,
assess protein differences between healthy and diseased cells, and
uncover not only each protein's specific function but also how it
interacts with other proteins.
Protoplast
The cellular material that remains after the cell wall has been removed from plant and fungal cells.
Pure culture
In vitro growth of only one type of microorganism.
R
Radioimmunoassay (RIA)
A
test combining radioisotopes and immunology to detect trace substances.
Such tests are useful for studying antibody interactions with cell
receptors, and can be developed into clinical diagnostics.
Rational drug design
Using
the known three-dimensional structure of a molecule, usually a protein,
to design a drug molecule that will bind to it. Usually viewed as an
alternative to drug discovery through screening many molecules for
biological activity.
Reagent
Substance used in a chemical reaction.
Recombinant DNA (rDNA)
The DNA formed by combining segments of DNA from two different sources.
Regeneration
Laboratory technique for forming a new plant from a clump of plant cells.
Regulatory gene
A gene that acts to control the protein-synthesizing activity of other genes.
Replication
Reproduction or duplication, as of an exact copy of a strand of DNA.
Replicon
A segment of DNA (e.g., chromosome or plasmid) that can replicate independently.
Repressor
A protein that binds to an operator adjacent to a structural gene, inhibiting transcription of that gene.
Restriction enzyme
An enzyme that breaks DNA in highly specific locations, creating gaps into which new genes can be inserted.
Restriction fragment length polymorphism (RFLP)
The
variation in the length of DNA fragments produced by a restriction
endonuclease that cuts at a polymorphic locus. This is a key tool in
DNA fingerprinting and is based on the presence of different alleles in
an individual. RFLP mapping is also used in plant breeding to see if a
key trait such as disease resistance is inherited.
Reticuloendothelial system
The system of macrophages, which serves as an important defense system against disease.
Retrovirus
A
virus that contains the enzyme reverse transcriptase. This enzyme
converts the viral RNA into DNA, which can combine with the DNA of the
host cell and produce more viral particles.
Rheology
Study of the flow of matter such as fermentation liquids.
Rhizobium
A
class of microorganisms that converts atmospheric nitrogen into a form
that plants can utilize for growth. Species of this microorganism grow
symbiotically on the roots of certain legumes, such as peas, beans and
alfalfa.
Ribonucleic acid (RNA)
A molecule similar to DNA that delivers DNA's genetic message to the cytoplasm of a cell where proteins are made.
Ribosome
A cellular component, containing protein and RNA, that is involved in protein synthesis.
RNA interference
A natural process used by organisms to block protein production.
S
Scale-up
Transition from small-scale production to production of large industrial quantities.
Selective medium
Nutrient material constituted such that it will support the growth of specific organisms while inhibiting the growth of others.
Sepsis
The
presence in the blood or other tissues of pathogenic microorganisms or
their toxins; the condition associated with such presence.
Sequencing
Decoding
a strand of DNA or gene into the specific order of its nucleotides:
adenine, cytosine, guanine and thymine. This analysis can be done
manually or with automated equipment. Sequencing a gene requires
analyzing an average of 40,000 nucleotides.
Serology
Study of blood serum and reactions between the antibodies and antigens therein.
Single-cell protein
Cells or protein extracts from microorganisms, grown in large quantities for use as protein supplements.
Somatic cells
Cells other than sex or germ cells.
Somatic cell gene therapy
Somatic
cell gene therapy involves the insertion of genes into cells for
therapeutic purposes; for example, to induce the treated cells to
produce a protein that the body is missing. It does not affect genetic
makeup of a patient's offspring and generally does not change all, or
even most, cells in the recipient. Somatic cell gene therapy is only
one way of applying the science of genomics to improve health care.
Somatic cell nuclear transfer
The transfer of a nucleus from a fully differentiated cell into an egg that has had its nucleus removed.
Splicing
The removal of introns and joining of exons to form a continuous coding sequence in RNA.
Stop codon
One of three codons in messenger RNA that signal the end of the amino acid chain in protein synthesis.
Structural gene
A gene that codes for a protein, such as an enzyme.
Substrate
Material acted on by an enzyme.
Suicide gene
A
gene that codes for an antibiotic that can kill the host bacterial
cell. It is genetically modified into the bacterium along with a
molecular switch that is controlled by a nutrient in the environment.
When the nutrient disappears, the suicide gene is switched on and the
bacterium dies.
Suppressor gene
A gene that can reverse the effect of a mutation in other genes.
Systems biology
A
hypothesis-driven field of research that creates predictive
mathematical models of complex biological processes or organ systems.
T
Technology transfer
The
process of transferring discoveries made by basic research
institutions, such as universities and government laboratories, to the
commercial sector for development into useful products and services.
Template
A molecule that serves as the pattern for synthesizing another molecule.
Terminator
Sequence of DNA bases that tells the RNA polymerase to stop synthesizing RNA.
Tertiary structure
The total three-dimensional shape of a protein that is essential to protein function.
Therapeutics
Compounds that are used to treat specific diseases or medical conditions.
Thymus
A
lymphoid organ in the lower neck, the proper functioning of which in
early life is necessary for development of the immune system.
Tissue culture
In vitro growth in nutrient medium of cells isolated from tissue.
Tissue plasminogen activator (tPA)
A protein produced in small amounts in the body that aids in dissolving blood clots.
T lymphocytes (T-cells)
White
blood cells that are produced in the bone marrow but mature in the
thymus. They are important in the body's defense against certain
bacteria and fungi, help B lymphocytes make antibodies and help in the
recognition and rejection of foreign tissues. T lymphocytes may also be
important in the body's defense against cancers.
Toxin
A poisonous substance produced by certain microorganisms or plants.
Transcription
Synthesis of messenger (or any other) RNA on a DNA template.
Transdifferentiation
The process whereby a specialized cell de-differentiates and
re-differentiates into a different cell type; or the process whereby an
adult stem cell from a specific tissue type becomes a cell type from a
very different tissue (for example a nerve stem cell differentiates
into a kidney cell).
Transduction
Transfer of genetic material from one cell to another by means of a virus or phage vector.
Transfection
Infection of a cell with nucleic acid from a virus, resulting in replication of the complete virus.
Transfer RNA (tRNA)
RNA molecules that carry amino acids to sites on ribosomes where proteins are synthesized.
Transformation
Change in the genetic structure of an organism by the incorporation of foreign DNA.
Transgenic organism
An
organism formed by the insertion of foreign genetic material into the
germ line cells of organisms. Recombinant DNA techniques are commonly
used to produce transgenic organisms.
Translation
Process by which the information on a messenger RNA molecule is used to direct the synthesis of a protein.
Transposon
A
segment of DNA that can move around and be inserted at several sites in
bacterial DNA or in a phage, thus alerting the host's DNA.
Tumor necrosis factors (TNFs)
Rare proteins of the immune system that appear to destroy some types of tumor cells without affecting healthy cells.
U
U Cell
Universal cell = embryonic stem cell.
V
Vaccine
A
preparation that contains an antigen, consisting of whole
disease-causing organisms (killed or weakened) or parts of such
organisms, that is used to confer immunity against the disease that the
organisms cause. Vaccine preparations can be natural, synthetic or
derived by recombinant DNA technology.
Vector
The agent (e.g., plasmid or virus) used to carry new DNA into a cell.
Virion
An elementary viral particle consisting of genetic material and a protein covering.
Virology
Study of viruses.
Virulence
Ability to infect or cause disease.
Virus
A
submicroscopic organism that contains genetic information but cannot
reproduce itself. To replicate, it must invade another cell and use
parts of that cell's reproductive machinery.
W
White blood cells
Leukocytes.
Wild type
The form of an organism that occurs most frequently in nature.
X
X-ray crystallography
An
essential technique for determining the three-dimensional structure of
biological molecules. This information aids in the discovery of
products that will interact with the biological molecule.
Xenobiotics
Synthetic
chemicals believed to be resistant to environmental degradation. A
branch of biotechnology called bioremediation is seeking to develop
biological methods to degrade such compounds.
Xenotransplantation
The transplantation of living organs, cells or tissues from animals into humans.
Y
Yeast
A general
term for single-celled fungi that reproduce by budding. Some yeasts can
ferment carbohydrates (starches and sugars) and thus are important in
brewing and baking.