Biotechnology

Genosensors Biosensors (electronic) that can
detect the individual nucleotides that com-
prise a genome (DNA) molecule. Automated
genosensors enable rapid, nondestructive
sequencing of DNA molecules. See also
GENOME
,
NUCLEOTIDE
,
DEOXYRIBONUCLEIC ACID
(
DNA
),
SEQUENCING
  (
OF DNA MOLECULES
),
TEM-
PLATE
,
BIOSENSORS
 (
ELECTRONIC
),
FOOTPRINTING
,
NANOTECHNOLOGY
,
BIOCHIPS
.
Genotoxic Refers to compounds that interfere
with normal functioning of genetic material
(i.e., DNA). For example, the antitumor anti-
biotic family of duocarmycin drugs. See also
DEOXYRIBONUCLEIC ACID
  (
DNA
),
GENOTOXIC
CARCINOGENS
,
FOOTPRINTING
.
Genotoxic Carcinogens Compounds that act
directly on the genetic material (i.e., DNA)
of an organism, thus causing cancer in that
organism. Of the numerous chemicals that
have been documented to be human carcin-
ogens, the majority of them are genotoxic.
See also 
CARCINOGEN
,
CANCER
,
GENE
,
DEOXY-
RIBONUCLEIC ACID
 (
DNA
).
Genotype The total genetic, or hereditary, con-
stitution that individuals receive from their
parents. An individual organism’s genotype
is distinguished from its phenotype, which
is its appearance or observable character. See
also
TRAIT
,
PHENOTYPE
,
WILD TYPE
.
Gentechnik Gesetz (Gene Technology Law)
The 1990 law that governs recombinant
DNA research and development in the coun-
try of Germany. It was amended January 1,
1994, to make it somewhat less restrictive.
See also 
ZKBS
  (
CENTRAL COMMISSION ON BIO-
LOGICAL SAFETY
),
RECOMBINANT DNA ADVISORY
COMMITTEE
  (
RAC
),
GENETIC ENGINEERING
,
RECOMBINANT DNA
  (
r
DNA
),
RECOMBINATION
,
© 2002 by CRC Press LLC

G
BIOTECHNOLOGY
,
BUNDESGESUNDHEITSAMT
 (
BGA
),
INDIAN DEPARTMENT OF BIOTECHNOLOGY
.
Genus A group of closely related species. See
also
SPECIES
,
CLADES
.
GEO Genetically engineered organism. See
also
GENETIC ENGINEERING
,
GMO
,
GENE
,
GENE
SPLICING
,
GMM
.
Geomicrobiology Applications of microbio-
logical knowledge to an understanding of geo-
logical phenomena. See also 
FERROBACTERIA
.
Germ Cell The sex cell (sperm or egg). It dif-
fers from other cells in that it contains only
half (haploid) the usual number of chromo-
somes. See also 
GAMETE
,
HAPLOID
.
Germ Plasm The total genetic variability to an
organism, represented by the total available
pool of germ cells or seed. See also 
ORGANISM
,
CELL
,
GERM CELL
,
GEM
.
German Gene Law See
GENTECHNIK GESETZ
(
GENE TECHNOLOGY LAW
).
GFP Green Fluorescent Protein. See also
GREEN FLUORESCENT PROTEIN
.
GH See
GROWTH HORMONE
.
Gibberellins Plant hormones that, among
other functions, regulate the growth of grass
species, including rice (after the relevant
gibberellin is activated by an enzyme). In
1996, Lew Mander and Richard Pharis dis-
covered an analogue (i.e., a chemical that is
similar) to grass gibberellin that does not
cause grass to grow. When this analogue is
sprayed onto grass, it mixes into the natu-
rally occurring grass gibberellin and signif-
icantly slows grass growth (thus potentially
reducing the amount of mowing required for
lawns, golf courses, etc.). See also 
PLANT
HORMONE
,
ENZYME
,
ANALOGUE
,
FUSARIUM
MONILIFORME
.
Gleevac
TM
See
GLEEVEC
™
.
Gleevec
TM
A pharmaceutical (imatinib mesy-
late, also known as STI571), developed and
trademarked by Novartis AG, used to treat
the blood cancer known as chronic myelog-
enous leukemia or chronic myeloid leukemia
or chronic myelocytic leukemia (CML).
CML results from a genetic defect (single-
nucleotide polymorphism) that causes
excessive production of white blood cells in
the body of the affected (human). That
excessive production of white blood cells
results when the defective gene (i.e., SNP)
causes excessive production of the enzyme
Bcr-Abl tyrosine kinase. Because Gleevec™
is a protein tyrosine kinase inhibitor, it
arrests excessive production of white blood
cells (and induces apoptosis — cell death —
in the cells that have the Bcr-Abl gene/SNP).
See also 
CANCER
,
WHITE BLOOD CELLS
,
GENE
,
MUTATION
,
SINGLE
-
NUCLEOTIDE POLYMORPHISMS
(
SNP
s
),
ENZYME
,
APOPTOSIS
,
PROTEIN TYROSINE
KINASE INHIBITOR
.
Glial Derived Neurotrophic Factor (GDNF)
A neurotrophic factor that assists the sur-
vival and functional activity of the brain’s
dopaminergic neurons. Because dopaminer-
gic neurons typically deteriorate and die in
brains of the victims of Parkinson’s disease,
it is possible that GDNF may someday be
used in treatment of Parkinson’s disease. See
also
NEUROTRANSMITTER
,
PARKINSON
’
S DISEASE
.
Globular Protein A soluble protein in which
the polypeptide chain is tightly folded in
three dimensions to yield a globular (roughly
oval, circular) shape. See also 
PROTEIN FOLD-
ING
,
POLYPEPTIDE
  (
PROTEIN
),
CONFORMATION
,
TERTIARY STRUCTURE
.
Glomalin A “sticky” protein molecule natu-
rally produced by certain fungi which grow
on most plant roots (in the soil). Glomalin
acts sort of like glue, thereby improving soil
stability by “gluing” soil into clumps. Proper
soil “clumping” (i.e., glomming together)
allows air and water to pass through that soil
more easily, increases the amount of carbon
contained within the soil (thereby removing
that “greenhouse gas” carbon dioxide from
the atmosphere), increases the number of
(“healthy”) bacteria in that soil, and
improves that soil’s overall fertility (i.e., its
ability to produce high-yield crops or a large
amount of biomass per hectare/acre). The
glomalin (and thus carbon) content of soil in
a field is increased by farmer utilization of
low-tillage or “no-tillage” methods of crop
production. See also 
PROTEIN
,
FUNGUS
,
BACTE-
RIA
,
BIOMASS
,
CONSERVATION TILLAGE
,
LOW
-
TILLAGE CROP PRODUCTION
,
NO
-
TILLAGE CROP
PRODUCTION
.
GLP See
GOOD LABORATORY PRACTICES
 (
GLP
).
GLQ223 See
TRICHOSANTHIN
.
Glucagon A hormone produced by the pan-
creas that causes the breakdown of glycogen
© 2002 by CRC Press LLC

G
in the liver. Glycogen is a form of storage
sugar and its breakdown releases glucose for
energy production. See also 
GLYCOGEN
,
HORMONE
,
GLUCOSE
,
PANCREAS
.
Glucan See
WATER SOLUBLE FIBER
,
POLYPHENOLS
.
Glucocerebrosidase (trade name Ceredase)
An enzyme used in treatment of inherited
Gaucher’s disease in which there is abnor-
mal deposition of glucocerebrosides (hydro-
phobic lipid molecules that contain a
hydrophilic sugar head group). Gaucher’s
disease is an enzyme deficiency disease that
may be amenable to cure by incorporation
of the gene coding for glucocerebrosidase
into the patient’s genome via gene delivery
techniques. See also 
ENZYME
,
GENE DELIVERY
.
Glucogenic Amino Acid Amino acids whose
carbon chains can be metabolically con-
verted by cells into glucose or glycogen. See
also
GLUCONEOGENESIS
,
CELL
,
AMINO ACID
,
METABOLISM
.
Gluconeogenesis The net biosynthesis (forma-
tion) of new glucose from noncarbohydrate
precursors such as pyruvate, lactate, glyc-
erol, acetyl-CoA (in plants), certain amino
acids, and intermediates of the citric acid
cycle. See also 
CARBOHYDRATES
,
GLUCOSE
(
GL
c
),
CITRIC ACID CYCLE
,
A
c
-
C
o
A
,
BIOTIN
.
Glucose (GLc) A prime fuel for the genera-
tion of energy by organisms. It is broken
down (to obtain energy) via a metabolic pro-
cess called glycolysis. Glucose is a hexose,
a sugar possessing six carbon atoms in its
molecule. The six carbon atoms are con-
nected to each other to form a closed ring
structure known as a hexose (6) ring.
Animal cells store glucose in the form of
glycogen (sometimes called animal starch),
a large branched polymer of glucose units.
Plant cells store glucose in the form of
starch, a large polymer of glucose units.
Yeasts and bacteria store glucose in the form
of dextran, a polymer of glucose units. The
difference between the forms of storage glu-
cose is (1) in the size (molecular weight) of
the final polymer formed, (2) in the type of
linkages that connect the single glucose units
together in the branched molecule, and (3) in
the degree of branching which occurs in the
polymer. Note that a glucose polymer does
not consist of just a single long straight
chain. The backbone chain has other poly-
mer chains branching off it. The whole mol-
ecule may be visualized as looking
somewhat like a tree without the trunk. The
other very abundant polymer formed by glu-
cose units is structural in nature and is called
cellulose. It is the most abundant cell wall
and structural polysaccharide in the plant
world. Hence, glucose is used not only as an
energy source, but also as a structural mate-
rial. See also 
AMYLOSE
,
AMYLOPECTIN
,
GLYCO-
LYSIS
,
GLUCONEOGENESIS
,
GLYCOGEN
,
STARCH
,
DEXTRAN
,
CELLULOSE
.
Glucose Isomerase An enzyme that catalyzes
the conversion of glucose to fructose. A mol-
ecule of fructose contains the same atoms as
a molecule of glucose (but in a different
arrangement). See also 
ENZYME
,
GLUCOSE
,
GENE FUSION
.
Glucose Oxidase An enzyme that breaks
down sugar molecules (causing oxygen con-
sumption in an organism). Industrial uses
include removing dissolved oxygen from
certain food products (e.g., sugar-containing
drink products). See also 
ENZYME
,
GLUCOSE
(
GL
c
),
GLYCOLYSIS
,
SUGAR MOLECULES
,
ORGANISM
.
Glucosinolates Toxins (neurotoxic phytotox-
ins) naturally produced in the seeds of some
plants (e.g., rapeseed, wild mustard (Bras-
sica juncea/Brassica rapa), grass pea
(Lathyrus sativus), etc.) in order to dissuade
wild animals from eating those plants’ seeds.
For example, when large amounts of grass
pea (Lathyrus sativus) are consumed by
humans, the glucosinolates build up in the
body and can cause lathyrism (i.e., an irre-
versible spastic paralysis of the legs). The
glucosinolates in rapeseed (Brassica rapa)
oil have been linked to heart damage in
humans who consume rapeseed (high erucic
acid) oil; plus those glucosinolates impart a
bitter taste to such plant oils.
The rapeseed glucosinolate 5-vinyl oxazo-
lidine I cyano-2-hydroxy-3-butene causes
poultry livers to hemorrhage (bleed inter-
nally) if it is fed via rapeseed meal or rapeseed
oil to poultry for several weeks (at 20% of
total diet). Such feeding of rapeseed meal/oil
to poultry also predispose those poultry to
develop Fatty Liver Syndrome (FLS), a met-
abolic disease. When glucosinolates from
© 2002 by CRC Press LLC

G
seeds of the wild mustard weed family are
mixed into canola meal (e.g., when those
weeds grew in a canola field and that result-
ant canola is processed into canola meal),
such canola meal must first be diluted (e.g.,
via mixing in some soybean meal) in order
to reduce glucosinolate concentration
(below the legal maximum allowance)
before it is fed to livestock in Canada. See
also
CANOLA
,
BRASSICA
,
TOXIN
,
PHYTOTOXINS
,
METABOLISM
,
SOYBEAN MEAL
.
Glufosinate See
PAT GENE
,
BAR GENE
,
HERBICIDE
-
TOLERANT CROP
,
GENE
,
GLUTAMINE SYNTHETASE
.
Gluphosinate See
PAT GENE
,
BAR GENE
,
HERBI-
C I D E
-
T O L E R A N T C R O P
,
G E N E
,
G L U T A M I N E
SYNTHETASE
.
Glutamate Dehydrogenase An enzyme found
naturally in certain soil bacteria, which helps
those bacteria to utilize soilborne nitrogen.
When its gene (GDH gene) is inserted into
corn plant via genetic engineering, the
resultant plant production of glutamate
dehydrogenase enables that corn plant to
better utilize soilborne nitrogen. As a result,
such genetically engineered corn (Zea
mays L.) has a protein yield increase of
approximately 10%, according to research
begun in 1991 by David Lightfoot. See also
ENZYME
,
BACTERIA
,
GENE
,
CORN
,
NITROGEN
CYCLE
,
DEHYDROGENASES
,
PROTEIN
,
GENETIC
ENGINEERING
.
Glutamic Acid A dicarboxylic amino acid of
the
α-ketoglutaric acid family. See also
AMINO ACID
.
Glutamine An amino acid; the monamide of
glutamic acid. Glutamine is of fundamental
importance for amino acid biosynthesis in
all forms of life. See also 
GLUTAMINE SYN-
THETASE
,
AMINO ACID
,
PAT GENE
,
BAR GENE
.
Glutamine Synthetase An enzyme that cata-
lyzes the synthesis of glutamine (which is
crucial for amino acid biosynthesis). See
also
GLUTAMINE
,
ENZYME
,
PAT GENE
,
BAR GENE
,
AMINO ACID
.
Glutathione A tripeptide that is found in all
cells of higher animals, which acts to help
protect against oxidative stress. Composed
of the amino acids glutamic acid, cysteine,
and glycine. The cysteine possesses a sulf-
hydryl group that makes glutathione a weak
reducing agent. See also 
OXIDATIVE STRESS
,
REDUCTION
 (
IN A CHEMICAL REACTION
).
Gluten A term used to refer to a naturally
occurring mixture of two different proteins —
glutenin and gliadin — in the seeds of bread
wheat (Triticum aestivum). In flour made
from traditional varieties of wheat, glutenin
proteins constitute approximately 50% of
the total gluten. The relative content of those
two proteins determines one of the most
commercially important properties of the
wheat (strength and elasticity of the flour
made from that particular wheat). For exam-
ple, more of the high molecular weight glu-
tenin (which is “stretchy” and imparts
physical strength to a dough made from such
flour, so that dough holds together while ris-
ing) results in a flour that is better suited to
manufacture higher-quality yeast-raised
bread products. See also 
WHEAT
,
PROTEIN
,
GLUTENIN
,
HIGH
-
GLUTENIN WHEAT
,
YEAST
,
MOLECULAR WEIGHT
,
POLYMER
.
Glutenin A protein naturally present in the
gluten within seeds of wheat (Triticum aes-
tivum). See also 
GLUTEN
,
WHEAT
,
PROTEIN
.
Glyceraldehyde (
D
- and 
L
-) One of the small-
est monosaccharides, it is called an aldose
because it contains an aldehyde group. Glyc-
eraldehyde has a single asymmetric carbon
atom; thus there are two stereoisomers
(
D
-glyceraldehyde and 
L
-glyceraldehyde).
See also 
MONOSACCHARIDES
,
STEREOISOMERS
.
Glycetein See
ISOFLAVONES
.
Glycine (gly) The simplest (and smallest) of
the amino acids found in proteins. It is the
only amino acid that does not have an asym-
metric carbon atom within its molecule. Thus,
it is not optically active. See also 
AMINO ACID
,
PROTEIN
,
STEREOISOMERS
,
OPTICAL ACTIVITY
.
Glycine max See
SOYBEAN PLANT
.
Glycinin One of the (structural) categories of
proteins that are produced within seeds of
legumes. In general, glycinins contain 3–4
times more cysteine (cys) and methionine
(met) per unit of protein than does 
β-con-
glycinin. See also 
PROTEIN
,
CYSTEINE
  (
cys
),
METHIONINE
 (
met
).
Glycitein See
ISOFLAVONES
.
Glycitin The
β-glycoside form (isomer in
which glucose is attached to molecule at the
7 position of the A ring) of the isoflavone
© 2002 by CRC Press LLC

G
known as glycitein (aglycone form). See also
ISOFLAVONES
,
ISOMER
,
GLYCITEIN
.
Glycoalkaloids See
ALKALOIDS
.
Glycobiology The study of the involvement
(function) of sugars in biological processes.
See also 
GLUCOSE
 (
GL
c
),
GLUCOSE OXIDASE
,
GLY-
COGEN
,
GLYCOLIPID
,
GLYCOLYSIS
,
GLYCOPROTEIN
,
GLYCOSIDASES
,
GLYCOSIDE
,
GLYCOSYLATION
.
Glycocalyx A polysaccharide matrix involved
(in some microorganisms) in firm attachment
of the organism to a solid surface.
Glycoform One of several molecular arrange-
ments that a given glycoprotein can possess
[varieties are determined by the attachment
of various oligosaccharide(s)]. Some glyco-
forms of a given glycoprotein may exhibit
greater or lesser biological activity (e.g.,
pharmaceutical effectiveness for biothera-
peutic glycoproteins) because the oligosac-
charide units of the glycoprotein molecule
mediate interactions of the glycoprotein with
the cells of the body. See also 
GLYCOPROTEIN
,
OLIGOSACCHARIDES
.
Glycogen A polymer of glucose with a branch-
ing, tree-like molecular structure. It is the
chief storage form of carbohydrates in ani-
mals. In mammals, glycogen is stored
mainly in the liver and muscles. Its molecu-
lar weight may be several million. See also
GLUCOSE
 (
GL
c
),
GLUCAGON
,
MOLECULAR WEIGHT
.
Glycolipid A lipid containing at least one car-
bohydrate group within its molecule. See
also
LIPIDS
,
GLYCOPROTEIN
,
GLYCOSYLATION
,
GLYCOLYSIS
.
Glycolysis A metabolic process in which sug-
ars are broken down into smaller compounds
with the release of energy. This series of
chemical reactions is found in plant and ani-
mal cells as well as in many microorganisms.
Except for the final reaction in the series, the
chemical reaction pathway of glycolysis is
the same as that for fermentation. See also
GLUCOSE
 (
GL
c
),
METABOLISM
,
FERMENTATION
.
Glycoprotein A conjugated protein containing
at least one carbohydrate (oligosaccharide)
group within its molecule. A commonly
occurring category of glycoproteins found in
nature is called mucoproteins. These are pro-
tein-polysaccharide compounds that occur in
the tissues, particularly in mucous secretions.
Other glycoproteins include lymphokines
(e.g., interleukins), hormones (e.g., soma-
totropins), receptors (e.g., GP120), enzymes
(e.g., tissue plasminogen activator), and
some therapeutics (e.g., CD4PE40). See also
GLYCOFORM
,
CONJUGATED PROTEIN
,
GP
120
PRO-
TEIN
,
CONJUGATE
,
PROTEIN
,
OLIGOSACCHARIDES
,
POLYSACCHARIDES
.
Glycoprotein C A blood-clot regulating gly-
coprotein. See also 
PROTEIN C
,
GLYCOPROTEIN
.
Glycoprotein Remodeling The use of restric-
tion endoglycosidases to (enzymatically)
remove sugar (i.e., oligosaccharide)
“branches” from glycoprotein (i.e., part pro-
tein, part oligosaccharide) molecules. One
reason to perform such glycoprotein remod-
eling would be to remove one or more oligo-
saccharide branches so that the glycoprotein
is less or no longer antigenic (i.e., triggers
an immune response). This allows the gly-
coprotein to be injected into the body (e.g.,
for pharmaceutical purposes) without incur-
ring an unwanted immune response. See also
GLYCOPROTEIN
,
RESTRICTION ENDOGLYCOSI-
DASES
,
ENZYME
,
OLIGOSACCHARIDES
,
ANTIGEN
,
CELLULAR IMMUNE RESPONSE
,
HUMORAL IMMU-
NITY
,
ANTIBODY
,
EPITOPE
,
HAPTEN
.
Glycosidases Enzymes that catalyze the cleav-
age (hydrolysis) of glycosidic molecular
bonds. For example, lysozyme (an enzyme
found in human tears) lyses (cuts up) certain
bacteria by cleaving the (
β configuration)
glycosidic linkages (bonds) between the
monosaccharide units that (when linked)
comprise the polysaccharide component of
the bacterial cell walls. A bacterial cell
devoid of a cell wall usually bursts. See also
ENDOGLYCOSIDASE
,
EXOGLYCOSIDASE
,
RESTRIC-
TION ENDOGLYCOSIDASES
.
Glycoside Any of a group of compounds that
yield sugar molecules on hydrolysis. All
parts of a glycoside compound may be sugar
molecules, so that sucrose, raffinose, starch,
and cellulose — all of which hydrolyze into
sugar molecules — may all be considered to
be glycosides. However, the name (glyco-
side) is usually applied to a compound in
which part of the molecule is not a sugar.
This nonsugar component is called the agly-
con. See also 
HYDROLYSIS
,
FRUCTAN
.