EBV = Epstein-Barr
virus.
Ectopic pregnancy Implantation and development
of a fetus at a site other than the uterus.
Ectoderm The outer germ layer of the embryo
giving rise to the epithelium of the skin.
Edema Accumulation of excess fluid in interstitial
space.
Efferent Carrying away from. opp. Afferent.
Eicosanoids Products of arachidonic acid
metabolism including prostaglandins, leukotrienes and thromboxanes.
Electron transport Flow of electrons
from reduced electron donors (e.g., NADH) to O2 via a series
of electron carriers located in the inner mitochondrial membrane, or from
H2O to NADP in the thylakoid membrane of plant chloroplasts.
In mitochondria and chloroplasts, electron movement is coupled to pumping
of H ions across the membrane, setting up the proton-motive force that
drives the formation of ATP.
Electrophoresis Separation method
of molecules such as proteins or nucleic acids on the basis of their charge-to-mass
ratio using electric force.
Electroporation A method for increasing
the rate of DNA uptake by protoplasts through prior exposure to a high
voltage which results in the temporary formation of small pores in the
cell membrane.
Elongation factor One of a group of non-ribosomal
proteins involved in translation of mRNA following initiation. Functions
include regulation of binding of an aminoacyl-tRNA to a ribosome and release
of tRNA after addition of an amino acid to the growing peptide chain.
Embryogenesis Early development
of an individual from a fertilized egg (zygote). Following cleavage of
the zygote, the major axes are established during the blastula stage;
in the subsequent gastrula stage, the early embryo invaginates and acquires
three cell layers.
Embryonic induction The interaction of cells
from two different germ layers, promoting differentiation, often reciprocal.
End-filling Conversion of a sticky
end to a blunt end by enzymatic synthesis of the complement to the single-stranded
extension.
Endocrine gland Group of cells that secrete
into the extracellular space hormones that then diffuse into bloodstream;
also called a ductless gland.
Endocytosis Uptake of extracellular materials
by invagination of the plasma membrane to form a small membrane-bounded
vesicle (endosome). Receptor-mediated endocvtosis involves the specific
uptake of a receptor-bound ligand typically by invagination of clathrin-coated
pits on the plasma membrane of animal cells..
Endoderm The innermost germ layer of the
embryo giving rise to the epithelial component of organs such as the gut,
liver, and lungs.
Endogenous opioid Certain neuropeptides ¾
endorphin, dynorphin, and enkephalin.
Endogenous pyrogen Cytokines (including IL-1,
probably IL-6 and tumor necrosis factor) that act physiologically in the
brain to cause fever.
Endoplasmic reticulum (ER)
Network of interconnected membranous structures within the cytoplasm of
eukaryotic cells. Two forms can be distinguished cytologically: rough
ER, which is associated with ribosomes and functions in the synthesis
and processing of secretory and membrane proteins, and smooth ER, which
lacks ribosomes and is involved in synthesis of lipids.
Endonuclease An enzyme that breaks
phosphodiester bond within a nucleic acid molecule.
Endorphin An endogenous opioid; functions
as neurotransmitter at synapses activated by opiate drugs and as paracrine
agent and hormone.
Endothelium An epithelial-like cell layer
lining spaces within mesodermally derived tissues, such as blood vessels
or lymphatics, and derived from the mesoderm of the embryo.
Endotoxin Lipopolysaccharide produced by
Gram-negative bacteria, which activates B cells and macrophages
Enkephalin Peptide neurotransmitter at some
synapses activated by opiate drugs; an endogenous opioid.
Enzyme induction An increase in synthesis
of an enzyme produced by, for example, hormonal stimulation.
Episome A plasmid capable of integration
into the host cell’s chromosome.
Epithelial Used of a culture to imply cells
derived from epithelium but often used more loosely to describe any cells
of a polygonal shape with clear, sharp boundaries between cells. Pavement-like
More correctly this should be termed “epithelioid” or “epithelial-like”
Epitheium A covering or lining of cells,
as in the surface of the skin or lining of the gut, usually derived from
the embryonic endoderm or ectoderm but exceptionally derived from mesoderm,
as with kidney tubules and mesothelium lining body cavities.
Epitopes The parts of an antigen which contact
the antigen binding site of antibody or the T-cell receptor
Epstein-Barr virus Causal agent of Burkitt’s
lymphoma and infectious mononucleosis, which has the ability to transform
human B cells into stable cell lines.
Erythrocyte Small biconcave blood
cell that contains hemoglobin, transports O2 and CO2
to and from the tissues of vertebrates and (in mammals) lacks a nucleus.
Ethanol precipitation Precipitation of
nucleic acid molecules by ethanol plus salt, used primarily as a means
of concentrating DNA or RNA.
Ethidium bromide A fluorescent chemical
that intercalates between base pairs in a double-stranded DNA molecule,
used in the detection of DNA.
Eubacteria Prokaryotic organisms
including the so-called true bacteria such as Escherichia coli
and Salmonella typhimurium. Phylogenetically distinct from archaebacteria.
Euchromatin Less condensed portions
of chromatin, including most transcribed regions.
Eukaryotes Class of organisms, including
all plants, animals, fungi, yeast, protozoa, and most algae, that are
composed of one or more cells containing a membrane-enclosed nucleus and
organelles. Opp. Prokaryotes.
Euploid Exact multiples of the haploid chromosome
set. The correct morphology characteristic of each chromosome pair in
the species from which the cells were derived is not implicit in the definition
but is usually assumed to be the case. Otherwise it should be stated as
“euploid but with some chromosomal aberrations”
Exocytosis Release of intracellular
molecules (e.g., hormones, matrix proteins) contained within a membrane-bounded
vesicle by fusion of the vesicle with the plasma membrane of a cell. This
is the process whereby most molecules are secreted from eukaryotic cells.
Opp. Endocytosis.
Exon Gene segment encoding protein.
Exonuclease An enzyme that sequentially
removes nucleotides from the ends of a nucleic acid molecule.
Explant A fragment of tissue transplanted
from its original site and maintained in an artificial medium.
Expression cloning Recombinant DNA
techniques for isolating a cDNA or genomic segment based on functional
properties of the encoded protein and without prior purification of the
protein.
Expression vector A cloning vector
designed so that a foreign gene inserted into the vector will be expressed
in the host organism.
Extracellular matrix A usually insoluble
network consisting of glycosaminoglycans, collagen, and various adhesive
proteins (e.g., laminin, fibronectin), which are secreted by animal cells.
It provides structural support in tissues and can affect the development
and biochemical functions of cells.
Extrinsic Coming from outside