Biotechnology

part of the amino acid sequence that can be
equated with a particular function. See also
COMBINING SITE
,
EPITOPE
,
IDIOTYPE
,
PROTEIN
,
p53
PROTEIN
,
MINIMIZED PROTEINS
.
Dominant (gene) (gene) See also 
DOMINANT
ALLELE
.
Dominant Allele Discovered by Gregor Men-
del in the 1860s, this gene produces the same
phenotype when it is heterozygous as it does
when it is homozygous (i.e., trait, or protein,
is expressed even if only one copy of the
gene is present in the genome). See also
GENETICS
,
RECESSIVE ALLELE
,
HETEROZYGOTE
,
HOMOZYGOUS
,
PHENOTYPE
,
GENOTYPE
,
GENOME
.
DON Abbreviation for the mycotoxin deox-
ynivalenol produced by Fusarium fungi
DON. Also known as “vomitoxin,” because
it can cause some animals to vomit if they
consume it. See also 
MYCOTOXINS
,
DEOXY-
NIVALENOL
,
FUSARIUM
,
FUNGUS
,
VOMITOXIN
.
Donor Junction The junction between the left
5
′ end of an exon and the right 3′ end of an
intron. See also 
EXON
,
INTRON
.
Double Helix The natural coiled conformation
of two complementary, antiparallel DNA
chains. This structure was first put forward
by Watson and Crick in 1953. See also
DEOXYRIBONUCLEIC ACID
 (
DNA
).
Down Promoter Mutations Those mutations
that decrease the frequency of initiation of
transcription. Down promoter mutations lead
to the production of less mRNA than is the
case in the nonmutated state. See also 
m
RNA
,
MUTATION
,
TRANSCRIPTION
,
DOWN REGULATING
.
Down Regulating Phrase referring to regula-
tory sequences, chemical compounds (e.g.,
transcription factors), mutations (e.g., down
promoter mutations), etc. that cause a given
gene to express less of the protein that it nor-
mally codes for. See also 
GENE
,
REGULATORY
SEQUENCE
,
TRANSCRIPTION FACTORS
,
DOWN PRO-
MOTER MUTATIONS
,
PROTEIN
,
CODING SEQUENCE
.
Drosophila The name of a type of fly (Droso-
phila melanogaster) that reproduces rapidly,
and that is commonly utilized in genetics
experiments due to its short life cycle
(14 days) and simple genome (four chromo-
some pairs). Because of these factors, a large
base of knowledge about Drosophila genet-
ics has been accumulated by the world’s sci-
entific community. For example, of the
nearly 300 “disease-causing” genes in the
human genome, more than half have an anal-
ogous gene in the Drosophila genome.
Drosophila was one of the first organisms to
have its entire genome sequenced by man.
See also 
GENETICS
,
GENOME
,
GENETIC CODE
,
GENETIC MAP
,
CHROMOSOMES
,
COLD HARDENING
,
HOMEOBOX
,
SEQUENCING
  (
OF DNA MOLECULES
),
GENE
.
Duchenne Muscular Dystrophy (DMD)
Gene See
MUSCULAR DYSTROPHY
 (
MD
).
Duplex The double-helical structure of DNA
(deoxyribonucleic acid). See also 
DOUBLE
HELIX
,
DEOXYRIBONUCLEIC ACID
 (
DNA
).
© 2002 by CRC Press LLC

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© 2001 by CRC Press LLC
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E
E-Selectin See
ELAM
-1
.
EAA See
ESSENTIAL AMINO ACIDS
.
EAA See
EXCITATORY AMINO ACIDS
 (EAAs).
Early Development The period of a phage
infection before the start of DNA replication.
See also 
PHAGE
,
BACTERIOPHAGE
,
DEOXYRIBO-
NUCLEIC ACID
 (
DNA
).
Early vs. Late Genes T h o s e   g e n e s   t r a n -
scribed early in a bacteriophage-mediated
infection process as compared to those genes
transcribed some time later. May require dif-
ferent “p factors” (sigma) for recognition of
promotors. See also 
GENE
,
PROMOTER
.
Early vs. Late Proteins During viral infection,
viral-specific proteins are synthesized at
characteristic times after infection. They are
called “early” and “late.” Often under posi-
tive control of bacterial and viral sigma fac-
tors. See also 
EARLY VS
.
LATE GENES
,
PROTEIN
.
Earthworms (Eisenia foetida) These worms
live in the soil and consume up to ten tons
of organic matter (old crop plant stalks,
husks, etc.) per acre (approximately 0.4 hect-
are) per year. In so doing, earthworms make
the soil more fertile, since the process breaks
down that organic matter into soil (when
excreted by those earthworms). Earthworm
tunnels also help aerate soil, which encour-
ages healthy plant root systems. See also
LOW
-
TILLAGE CROP PRODUCTION
,
GLOMALIN
,
NO
-
TILLAGE CROP PRODUCTION
.
E. coli See
ESCHERICHIA COLIFORM
 (
E
.
COLI
).
E. coli 0157:H7 See
ESCHERICHIA COLIFORM
0157
:
H
7
 (
E
.
COLI
0157
:
H
7
).
ECB See
EUROPEAN CORN BORER
 (
ECB
).
Ecology The study of the interrelationships
between organisms and their environments.
See also 
HABITAT
.
Ectodermal Adult Stem Cells Certain stem
cells present within (adult) bodies of organ-
isms, that can be differentiated (via chemical
signals) to give rise to cells of skin, hair,
tooth enamel, mucous membranes, and some
glandular tissues. See also 
STEM CELLS
,
MUL-
TIPOTENT ADULT STEM CELLS
,
CELL
,
ORGANISM
,
SIGNALING
.
Edible Vaccines Edible substances, bearing
antigens, that cause activation of an animal’s
immune system via that animal’s GALT
(gut-associated lymphoid tissues). These
“edible vaccines” are derived from transgenic
plants (grains, tubers, fruits, etc.) or eggs
(i.e., via the activation of the hen’s immune
system to cause that hen to secrete desired
molecule(s) into the eggs it lays). See also
GUT
-
ASSOCIATED LYMPHOID TISSUES
 (
GALT
),
ANTI-
GEN
,
CELLULAR IMMUNE RESPONSE
,
MOLECULAR
PHARMING
™
,
HUMORAL IMMUNITY
,
PLANTIGENS
.
EDTA Ethylenediamine tetraacetate. An organic
molecule which, due to the chemical groups
it contains and their juxtaposition within that
molecule, is able to chelate (bind) certain
other molecules such as divalent metal cations.
EDTA thus inhibits some enzymes requiring
such ions for activity. See also 
CHELATION
,
COFACTOR
,
CHELATING AGENT
.
EFA See
ESSENTIAL FATTY ACIDS
.
Effector A class of (usually small) molecules
that regulates the activity of a specific protein
(e.g., enzyme) molecule by binding to a spe-
cific site on the protein. Control of (existing)
enzyme molecules may be achieved by com-
bination of the effector with the enzyme. The
effector molecule may either physically
block the active site on the enzyme mole-
cule, or alter the three-dimensional confor-
mation of the enzyme molecule. That
conformation change results in a change in
the enzyme’s catalytic activity. Effector is a
general term. Effector molecules may be
activators (cause an increase in the enzyme’s
catalytic activity) or inhibitors (cause a
© 2002 by CRC Press LLC

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decrease in the enzyme’s catalytic activity).
A special class of effector, known as an
allosteric effector, binds to the enzyme mol-
ecule at a site other than the enzyme’s active
site (thereby activating or inhibiting). See
also
PROTEIN
,
ENZYME
,
CONFORMATION
,
ALLOS-
TERIC ENZYMES
,
ALLOSTERIC SITE
,
ACTIVE SITE
,
FEEDBACK INHIBITION
,
CATALYTIC SITE
.
EGF See
EPIDERMAL GROWTH FACTOR
 (
EGF
).
EGF Receptor A protein embedded in the
surface of the membranes of skin cells. The
receptor consists of (1) an outside (of the
cell membrane) enzyme that recognizes epi-
dermal growth factor (EGF) and binds to it,
and (2) an enzyme on the inside of the cell
membrane, which is of the tyrosine kinase
class. When free EGF comes in contact with
an EGF receptor, they bind (in a lock-and-
key fashion) and then enter the cell together
(through the cell membrane. There EGF
stimulates growth or division of the cell via
ras protein and ras gene). The EGF receptor
(and receptors in general) is like a butler who
allows the EGF (a guest) to enter the cell
(home). See also 
ONCOGENES
,
PROTEIN
,
PLASMA
MEMBRANE
,
TRANSMEMBRANE PROTEINS
,
ras
GENE
,
ras
PROTEIN
,
RECEPTORS
,
SIGNAL TRANSDUCTION
.
EGFR See
EGF RECEPTOR
.
EHEC See
ENTEROHEMORRHAGIC E
.
COLI
.
EIA See
ENZYME IMMUNOASSAY
 (
EIA
).
Eicosanoids A group of chemical compounds
which the human body synthesizes (manu-
factures) from arachidonic acid, docosahex-
anoic acid, and other starting materials. One
subgroup of eicosanoids is that of the pros-
taglandins (cyclic fatty acids that act as hor-
mones in the body). For example, the COX-1
enzyme converts arachidonic acid to consti-
tutive prostaglandins, and the COX-2
enzyme converts arachidonic acid to induc-
ible prostaglandins. See also 
ARACHIDONIC
ACID
  (
AA
),
CYCLOOXYGENASE
,
CONSTITUTIVE
ENZYMES
,
INDUCIBLE ENZYMES
,
PROSTAGLAN-
DINS
,
HORMONE
,
COX
-1
,
COX
-2,
LEUKOTRIENES
.
Eicosapentaenoic Acid (EPA) See
EICOSAPEN-
TANOIC ACID
 (
EPA
).
Eicosapentanoic Acid (EPA) O n e   o f   t h e
omega-3 (n-3) polyunsaturated fatty acids
(PUFA), EPA is important for the develop-
ment of the human brain, retina tissue,
prevention of high blood pressure, coronary
heart disease (CHD), and some cancers. The
human body converts linolenic acid (e.g.,
from consumption of soybean oil) to the two
highly unsaturated fatty acids (HUFA) eicos-
apentanoic acid (EPA) and docosahexanoic
acid (DHA). See also 
N-
3
FATTY ACIDS
,
POLY-
UNSATURATED FATTY ACIDS
  (
PUFA
),
UNSATUR-
ATED FATTY ACIDS
,
ESSENTIAL FATTY ACIDS
,
CORONARY HEART DISEASE
  (
CHD
),
CANCER
,
HIGHLY UNSATURATED FATTY ACIDS
  (
HUFA
),
LINOLENIC ACID
,
SOYBEAN OIL
.
ELAM-1 Also known as E-selectin, it is a
selectin molecule that is synthesized by
endothelial cells after (adjacent) tissue is
infected. ELAM-1 molecules then help leu-
kocytes leave the bloodstream to fight the
infection. See also 
SELECTINS
,
LECTINS
,
ADHE-
SION MOLECULES
,
LEUKOCYTES
.
Elastase An enzyme secreted by neutrophils
(white blood cells that engulf pathogens)
which catalyzes the cleavage (breakdown) of
specific proteins that function to provide
elasticity to certain tissues. May be indi-
rectly responsible for some autoimmune dis-
eases, such as arthritis (which results from
breakdown of cartilage tissue). Elastase may
also be indirectly responsible for the emphy-
sema (caused by loss of lung elasticity) that
results from prolonged smoke inhalation.
When a-1 antitrypsin (anti-elastase) efficacy
is reduced (via smoke), the now-unrestrained
excess elastase destroys alveolar walls in the
lungs by digesting elastic fibers and other
connective tissue proteins. See also 
LEUKO-
CYTES
,
NEUTROPHILS
,
PROTEOLYTIC ENZYMES
.
Electrolyte Any compound (salt, acid, base,
etc.) which in aqueous solution dissociates
into ions (charged atom-sized particles).
Electrolytes may either be strong (com-
pletely or nearly completely dissociated) or
weak (only partially dissociated). See also
ION
.
Electron Carrier A protein, such as flavopro-
tein or a cytochrome, that can gain and lose
electrons reversibly and function in the
transfer of electrons from one carrier to
another until the electron is taken up by a
final molecule or atom such as oxygen. See
also
PROTEIN
,
CYTOCHROME
.
Electron Microscopy (EM) A technique for
greatly magnifying and visualizing very
© 2002 by CRC Press LLC

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small entities such as viruses and even large
molecules. The technique uses beams of
electrons instead of light rays. Because of
the physics involved, beams of electrons per-
mit much greater magnification than is pos-
sible with a light microscope. Electron
microscopes have been used to examine the
structures of viruses, bacteria, pollen grains,
molecules, etc.
Electropermeabilization See
ELECTROPORATION
.
Electrophoresis A technique for separating
molecules based on the differential move-
ment of charged particles through a matrix
when subjected to an electric field. The term
is usually applied to large ions of colloidal
particles dispersed in water. The most impor-
tant use of electrophoresis (currently) is in
the analysis of proteins, and then a technique
known as gel electrophoresis is used. Since
the proportion of proteins varies widely in
different diseases, electrophoresis can be
used for diagnostic purposes. Electrophoresis,
through agarose or other gel matrices, is a
common way to separate, identify, and
purify plasmid DNA, DNA fragments result-
ing from digestion (of DNA) with restriction
endonucleases, and RNA. Electrophoresis is
also used to study bacteria and viruses,
nucleic acids, and some types of molecules,
including amino acids. See also 
PROTEIN
,
AMINO ACID
,
BIOLUMINESCENCE
,
POLYACRYLAMIDE
GEL ELECTROPHORESIS
 (
PAGE
),
TWO
-
DIMENSIONAL
(
2
D
)
GEL ELECTROPHORESIS
,
CHROMATOGRAPHY
,
GEL
,
AGAROSE
,
PLASMID
,
DEOXYRIBONUCLEIC
ACID
 (
DNA
),
RESTRICTION ENDONUCLEASES
,
RIBO-
NUCLEIC ACID
 (
RNA
),
BACTERIA
,
VIRUS
,
BIOMEMS
.
Electroporation A process utilized to intro-
duce a foreign gene into the genome of an
organism. In 1995, the U.S. company Dekalb
Genetics Corp. received a patent for produc-
ing genetically engineered corn via introduc-
tion of a foreign gene into corn cells via
electroporation. Electroporation, also called
electroporesis or electropermeabilization,
uses a brief direct-current (dc) electrical
pulse to cause formation of “micropores”
(tiny holes) in the surface of cells or proto-
plasts suspended in a solution (water) con-
taining DNA sequences (genes). After the
gene(s) enter the cell via the temporarily
created micropores, the electrical pulse
ceases, and the micropores close so that the
gene(s) cannot depart the cell. The cell then
incorporates (some) of the new genetic
material (genes) into its genetic complement
(genome), and creates whatever product
(i.e., a protein) the newly-introduced gene
codes for. See also 
CODING SEQUENCE
,
GENETIC
ENGINEERING
,
VECTOR
,
BIOLISTIC
®
GENE GUN
,
“
EXPLOSION
”
METHOD
,
AGROBACTERIUM TUMEFA-
CIENS
,
GENE
,
GENOME
,
CELL
,
CORN
,
PROTOPLAST
,
DEOXYRIBONUCLEIC ACID
 (
DNA
),
PROTEIN
.
Electroporesis See
ELECTROPORATION
.
ELISA (test for proteins) An enzyme-linked
immunosorbent assay (hence the acronym)
which can readily measure less than a nan-
ogram (10
–9
 g) of a protein. This assay is
more sensitive than simple immunoassay
(tests) because one of the two antibodies
used to bind and quantitate (measure) the
protein’s antigen, based on two concurrent
epitopes within the protein, is attached to an
enzyme. The enzyme can rapidly convert an
added colorless substrate into a colored
product or a nonfluorescent substrate into an
intensely fluorescent product (thus enabling
finer quantitation). See also 
ABSORBANCE
 (
A
),
IMMUNOASSAY
,
PROTEIN
,
ANTIGEN
,
ENZYME
,
NANOGRAM
 (
ng
),
FLUORESCENCE
.
Elite Germplasm Refers to germplasm that is
adapted (selectively bred) and optimized to
new surroundings (i.e., environment). For
example, corn/maize (Zea mays L.),  which
is native to Mexico, has been adapted and
optimized to grow in field conditions in
many of the world’s countries. See also
GERMPLASM
,
INTROGRESSION
,
MARKER ASSISTED
SELECTION
,
CORN
.
Ellagic Acid A naturally occurring plant phe-
nol (phytochemical) that, when consumed
by humans, has been shown to help inhibit
some cancers. Ellagic acid is naturally
present in strawberries, the pomegranate
( P u n i c a   g r a n a t u m ) ,   e t c .   S e e   a l s o
PHYTOCHEMICALS
,
POLYPHENOLS
,
CANCER
.
EMAS Eco-Management and Audit Scheme.
Embryo Rescue Refers to the tissue culture
techniques/technologies utilized to enable
the fertilized embryo resulting from a “wide
cross” (between two nonsexually compatible
plant species) to grow and mature into a seed
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E
producing plant. See also 
TRADITIONAL BREED-
ING METHODS
,
WIDE CROSS
,
TISSUE CULTURE
.
Embryology The study of the early stages in
the development of an organism. In these
stages a single highly specialized cell, the
egg, is transformed into a complex many-
celled organism resembling its parents. See
also
CELL
,
ANTIANGIOGENESIS
,
GAMETE
.
Embryonic Stem Cells See
HUMAN EMBRYONIC
STEM CELLS
.
EMEA See
EUROPEAN MEDICINES EVALUATION
AGENCY
 (
EMEA
).
Emulsion A stable dispersion of one liquid in a
second, immiscible (i.e., nonmixable) liquid.
For example, milk is an emulsion of oil (fat)
in water, and latex paint is an emulsion of
paint resin in water. Certain ingredients (e.g.,
β-conglycinin protein) help enable a greater
content of the first liquid to be dispersed in
the second liquid. Certain ingredients (e.g.,
β-conglycinin protein) make a given emul-
sion more stable (i.e., prevent the two liquids
from separating over an extended period of
time). See also 
PROTEIN
,
β
-
CONGLYCININ
.
Enantiomers From the Greek word enantios,
which means opposite. Enantiomers are a
pair of nonidentical, mirror-image mole-
cules. This means that both molecules are
made up of the same atoms, i.e., they have
the same molecular formula, but the constit-
uent groups that are attached to a carbon
atom can be arranged in two different ways
(forms) around the carbon atom. This gives
rise to an asymmetric molecule that can exist
in either of two mirror-image forms whose
mirror images are not superimposable. A pair
of these molecules is known as enantiomers.
The four attached groups are all different
from each other. See also 
RACEMATE
,
OPTICAL
ACTIVITY
,
CHIRAL COMPOUND
,
ENANTIOPURE
.
Enantiopure Refers to a compound (e.g., a
pharmaceutical) that consists of only one of
that compound’s two possible enantiomers.
Sometimes expressed in relative terms. For
example, 98% enantiopure would refer to a
compound that consists of 98% (of) desired
enantiomer. See also 
ENANTIOMERS
,
CHIRAL
COMPOUND
,
RACEMATE
,
OPTICAL ACTIVITY
.
Endergonic Reaction A chemical reaction with
a positive standard free energy change (i.e., an
“uphill” reaction). An (heat) energy-requiring
reaction. A nonspontaneous reaction at
ambient temperature. See also 
EXERGONIC
REACTION
,
FREE ENERGY
.
Endocrine Glands Glands that secrete their
products (hormones) into the blood, which
then carries them to their specific target
organs. For example, adrenalin, produced in
the adrenal glands, is carried to the heart
(and other muscles) when needed during
periods of stress. The endocrine glands are:
the pituitary, thyroid, adrenals, pancreas,
ovaries (in females), and testes (in males).
Endocrine glands are found in some inver-
tebrates as well as in vertebrates. See also
HORMONE
,
ENDOCRINE HORMONES
.
Endocrine Hormones The products secreted
by the endocrine glands. These help control
long-term bodily processes, such as growth,
lactation, sex cycles, and metabolic adjust-
ment. The endocrine system and the nervous
system are interdependent and often referred
to collectively as the neuroendocrine system.
For example, the juvenile hormone, found in
insects and annelids, affects sexual matura-
tion. There is currently great interest among
scientists in the potential use of such hor-
mones in the control of destructive insects. See
also
ENDOCRINE GLANDS
,
HORMONE
,
PHEROMONES
.