Biotechnology

Growth Hormone (GH) A   h o r m o n e   p r o -
duced by the anterior pituitary gland. This
hormone is a protein (somatotropin) and can
be obtained from the bodies of animals, or
produced by genetically engineered micro-
organisms. Its major action in humans
(human growth hormone) is a generalized
stimulation of skeletal growth. However,
human growth hormone (HGH) is also
known to affect the growth of other tissues,
to be important in fat, protein, and carbohy-
drate metabolism, and to enhance the effects
of various other hormones. See also 
BOVINE
SOMATOTROPIN
  (
BST
),
PORCINE SOMATOTROPIN
(
PST
),
PITUITARY GLAND
.
Growth Hormone-Releasing Factor (GRF or
GHRF) Also termed growth hormone-
releasing hormone (GRH). A factor that
causes the release of growth hormone, it is
44 amino acids in length. See also 
GROWTH
HORMONE
  (
GH
),
GROWTH FACTOR
,
AMINO ACID
,
HORMONE
.
GT-AG Rule Describes the presence of these
constant dinucleotides at the first two and
last two positions of introns of nuclear
genes. See also 
INTRON
,
GENE
.
GT/PT Correlation Abbreviation for Geno-
type/Phenotype Correlation. See also 
GENO-
TYPE
,
PHENOTYPE
.
GTO Abbreviation for Gene Technology Office.
See also 
GENE TECHNOLOGY OFFICE
.
GTP See
GMP
.
GTPases Guanosine triphosphatases. These
are G-proteins (enzymes) which are crucial
for growth, movement, and maintenance of
the cell’s shape. When active, GTPases are
bound to cell membranes (surfaces) by an
isoprene molecule (receptor). See also 
G-PRO-
TEINS
,
ENZYME
,
CELL
,
PHOSPHORYLATION
,
RECEP-
TORS
,
PROTEIN
.
GTR See
GENE TECHNOLOGY REGULATOR
 (
GTR
).
GTS Glyphosate tolerant soybean. See also
HERBICIDE
-
TOLERANT CROP
,
SOYBEAN PLANT
,
CP
4
EPSPS
,
GLYPHOSATE
.
GTS Glufosinate-ammonium tolerant soy-
bean. See also 
HERBICIDE
-
TOLERANT CROP
,
SOY-
BEAN PLANT
,
PAT GENE
,
GLUFOSINATE
.
Guanine A purine base. It occurs naturally as
a fundamental component of nucleic acids.
See also 
PURINE
,
NUCLEIC ACIDS
.
GURTs See
GENETIC USE RESTRICTION TECHNOL-
OGIES
.
GUS See
GUS GENE
.
GUS Gene A gene that codes for production of
β-glucuronidase (i.e., GUS protein) in Escher-
ichia coli bacteria. The GUS gene is com-
monly utilized as a “marker gene” for
genetically engineered plants. 
β-glucuronidase
causes a color change, in the presence of the
chemical 5-bromo-4-chloro-3-indoyl-beta-
D
-
glucuronic acid, by cleaving (‘cutting’) a glu-
curonic acid molecule off the 5-bromo-4-
chloro-3-indoyl-beta-
D
-glucuronic acid. The
(remaining) molecule is an insoluble blue dye.
See also 
GENE
,
CODING SEQUENCE
,
ESCHERICHIA
COLIFORM
  (
E
.
COLI
),
MARKER
  (
GENETIC MARKER
),
GENETIC ENGINEERING
.
© 2002 by CRC Press LLC

G
Gut-Associated Lymphoid Tissues (GALT)
A variety of specialized lymph-reticular tis-
sues that line the inside of an animal’s diges-
tive system. GALT include Peyer’s Patches,
the appendix, and small solitary lymphoid
tissues in the gut. They constitute the intes-
tinal immune system (response to antigens).
See also 
LYMPHOCYTE
,
PEYER
’
S PATCHES
,
ANTI-
GEN
,
HUMORAL IMMUNITY
,
CELLULAR IMMUNE
RESPONSE
, “
EDIBLE VACCINES
”,
PLANTIGENS
.
© 2002 by CRC Press LLC

0-8493-XXXX-X/01/$0.00+$1.50
© 2001 by CRC Press LLC
H
H
H. pylori A bacteria that has been linked (e.g.,
cause) to gastric ulcers and other gastric prob-
lems in humans. That link was first
announced by Barry Marshall in the early
1990s. See also 
BACTERIA
,
HELICOBACTER PYLORI
.
H. virescens See
HELIOTHIS VIRESCENS
  (
H
.
VIRE-
SCENS
).
H. zea See
HELICOVERPA ZEA
 (
H
.
ZEA
).
HA Abbreviation for the word hemagglutinin.
See also 
HEMAGGLUTININ
.
Habitat The natural environment of an organ-
ism within an ecosystem. The place, in an
ecosystem, where an organism lives. See
also
ECOLOGY
.
HAC See
HUMAN ARTIFICIAL CHROMOSOMES
 (
HAC
).
HACCP See
HAZARD ANALYSIS AND CRITICAL
CONTROL POINTS
 (
HACCP
).
Hairpin Loop A section of highly curving,
single-stranded DNA or RNA formed when
a long piece (string) of the DNA or RNA
bends back on itself and hydrogen-bonds (is
able to base pair) in some regions to form
double-stranded regions. The structure can
be visualized by taking a human hair, bend-
ing it back on itself and holding it in such a
way as to half its original length. The section
where the two ends of hair lie next to each
other represents the section of double-
stranded DNA or RNA. At one end the hair
will have to make a sharp turn and will form
a loop. This loop represents the single-
stranded hairpin loop. See also 
RIBONUCLEIC
ACID
 (
RNA
),
DEOXYRIBONUCLEIC ACID
 (
DNA
).
Halophile Microorganisms that require NaCl
(salt) for growth (they are called obligate
halophiles). Those that do not require it, but
can grow in the presence of high NaCl con-
centrations, are called facultative halophiles.
Natural habitats containing high salt concen-
trations are, for example, the Great Salt Lake
in Utah, the Dead Sea in Israel, and the Cas-
pian Sea in Russia. See also 
HABITAT
.
HAP Gene See
LOW
-
PHYTATE CORN
.
Haploid A cell with one set of chromosomes;
half as many chromosomes as the normal
somatic body cells contain. A characteristic
of sex cells. See also 
GAMETE
.
Haplophase A phase in the life cycle of an
organism in which it has only one copy of
each gene. The organism is then said to be
haploid. Yeast can exist as true haploids.
Humans are haploid for only a few genes
and cannot exist as true haploids. See also
HAPLOID
.
Haplotype A subgroup (e.g., an ethnic minor-
ity, all members of a genetically related fam-
ily group, etc.) of organisms (e.g., humans)
whose phenotype results in their body
responding in the same way to a physical
agent (a certain pharmaceutical, a toxin, a
food, etc.). For example, more than 70% of
black people in North America are lactose
intolerant (their bodies cannot metabolize
the lactose sugar in cow’s milk), but fewer
than 19% of Caucasian people in North
America are lactose intolerant. Analogous to
that, the drugs acetaminophen, aspirin, and
Valium remain in the bodies of women (who
constitute a haplotype) longer than in the
bodies of men. Haplotypes for the 
β2-adren-
ergic gene are predictive of asthma patients’
response to the pharmaceutical albuterol.
See also 
PHARMACOGENOMICS
,
HERITABILITY
,
HEREDITY
,
TRAIT
,
GENETICS
,
PHENOTYPE
,
TOXIN
,
INSULIN
,
METABOLISM
,
SINGLE
-
NUCLEOTIDE
POLYMORPHISMS
 (
SNP
s
).
Hapten A small foreign molecule that will
stimulate an immune system response (e.g.,
antibody production) if the small molecule
(now called a haptenic determinant) is
© 2002 by CRC Press LLC

H
attached to a macromolecule (carrier) to
make it large enough to be recognized by the
immune system. See also 
EPITOPE
,
CELLULAR
IMMUNE RESPONSE
,
HUMORAL IMMUNITY
.
Haptoglobin A protein which is a component
in human blood; that can occur in one of two
different molecular forms (i.e., a “large” ver-
sion of that molecule or a “small” version of
that molecule). The “small” version of hap-
toglobin is very effective at capturing and
removing free radicals (high-energy oxygen
atoms which bear an “extra” electron) from
the bloodstream before they damage tissues
(e.g., in the eye, kidneys, and/or arteries).
The “large” version of haptoglobin, which
is the only haptoglobin molecule in the
bloodstream of one particular haplotype
(genetic subgroup) of people, is not effective
at capture/removal of those free radicals
(e.g., generated at a high rate in people with
diabetes disease), so diabetics within that
particular haplotype tend to suffer extreme
damage to eyes, kidneys, and arteries (some-
times necessitating limb amputation). See
also
FREE RADICAL
,
HAPLOTYPE
,
INSULIN
,
OXI-
DATIVE STRESS
.
Hardening See
COLD HARDENING
,
HYDROGENA-
TION
.
Harpin A protein naturally produced by the
Erwinia amylovora bacteria (which usually
causes the plant disease known as fire blight
in apple trees, pear trees, and some ornamen-
tal plants of the rose family). Discovered in
1992 by Zhong-Min Wei and colleagues,
harpin causes numerous species of plants to
initiate a protective/defensive response (cas-
cade) against bacteria, viruses, fungi, and
some insects and nematodes. Harpin also
causes plants (i.e., that it is sprayed onto) to
increase their photosynthesis and to have
increased root growth/proliferation; which
can lead to greater crop yields. See also 
PRO-
TEIN
,
BACTERIA
,
PHYTOALEXINS
,
PATHOGENESIS
RELATED PROTEINS
,
SIGNALING
,
SIGNALING MOL-
ECULE
,
SIGNAL TRANSDUCERS AND ACTIVATORS
OF TRANSCRIPTION
 (
STAT
s
),
SALICYLIC ACID
 (
SA
),
JASMONIC ACID
,
SYSTEMIC ACQUIRED RESISTANCE
(
SAR
),
CASCADE
,
R GENES
,
NEMATODES
.
Harvesting A term used to describe the recov-
ery of microorganisms from a liquid culture
(in which they have been grown by man).
This is usually accomplished by means of
filtration or centrifugation. See also 
MICRO-
ORGANISM
,
CULTURE MEDIUM
,
ULTRACENTRI-
FUGE
,
DIALYSIS
.
Harvesting Enzymes Enzymes that are used to
gently dissociate (break apart) cells in living
tissues in order to produce single, separate
cells that can then be established and propa-
gated in a cell culture reactor. Harvesting
enzymes are also used to dissociate cells that
have been grown for some time in a cell cul-
ture reactor. See also 
CELL CULTURE
,
MAMMA-
LIAN CELL CULTURE
,
ENZYME
,
CULTURE MEDIUM
.
Hazard Analysis and Critical Control Points
(HACCP) A quality control program (for
food processing) to systematically prevent
hazards (e.g., pathogens) from entering the
production process. HACCP was initially
developed in the 1950s by the Pillsbury
Company to supply food products for astro-
nauts in America’s space program. Under
HACCP, food processors/handlers must ana-
lyze and identify in advance the points where
hazards are most likely to occur, and elimi-
nate them. For example, because melons lie
in pathogen-contaminated dirt while grow-
ing, a “critical control point” for restaurants
serving sliced melon is cleansing of the knife
after each melon is cut (to prevent the knife
carrying pathogens from one infected melon
to other melons). See also 
PATHOGEN
,
RAPID
MICROBIAL DETECTION
 (
RMD
).
Heat-Shock Proteins See
STRESS PROTEINS
.
Heavy-Chain Variable (VH) Domains T h e
regions (domains) of the antibody (mole-
cule’s) “heavy chain” that vary in their
amino acid sequence. The “chains” (of
atoms) comprising the antibody (immuno-
globulin) molecule consist of a region of
variable (V) amino acid sequence and a
region in which the amino acid sequence
remains constant (C). An antibody molecule
possesses two antigen binding sites, and it
is the variable domains of the light (VL) and
heavy (VH) chains which contribute to this
antigen binding ability. See also 
ANTIBODY
,
PROTEIN
,
IMMUNOGLOBULIN
,
SEQUENCE
  (
OF A
PROTEIN MOLECULE
),
ANTIGEN
,
AMINO ACID
,
COMBINING SITE
,
DOMAIN
 (
OF A PROTEIN
),
LIGHT
-
CHAIN VARIABLE
 (
VL
)
DOMAINS
.
© 2002 by CRC Press LLC

H
Hedgehog Proteins Signaling molecules (con-
sisting of “signaling protein” with cholesterol
molecule attached to it), that direct/control
tissue differentiation during mammal embryo
development (into various organs, limbs,
etc.). The signaling protein (within an embryo
cell) cleaves itself into two peptides, one of
which then acts as a transferase (i.e., enzyme
that catalyzes the addition of a functional
group to a given molecule — in this case to
the other “hedgehog peptide”). When the cell
then secretes the cholesterol/peptide mole-
cule, the cholesterol (functional group)
“anchors” it to the cell surface, while the “sig-
naling protein” end of the cholesterol/peptide
directs differentiation of nearby cells. See
also
PROTEIN
,
SIGNALING MOLECULES
,
SIGNALING
,
CHOLESTEROL
,
SIGNAL TRANSDUCTION
,
PEPTIDE
,
CELL
,
TRANSFERASES
,
ENZYME
,
FUNCTIONAL
GROUP
,
CELL DIFFERENTIATION
.
Helicobacter pylori Bacteria. See also 
H
.
PYLORI
.
Helicoverpa zea (H. zea) Known as the corn
earworm (when it is on corn plants), and
known as the tomato fruitworm (when it is on
tomato plants), this is one of three insect spe-
cies that is called “bollworms” (when on cot-
ton plants). H. zea chews on those crop plants,
and is one of the insects that can act as a
vector (carrier) of Aspergillus flavus fungus.
In 1997, scientists at the U.S. Department of
Agriculture created/optimized a monoclonal
antibody against Helicoverpa zea vitellin,
which thus holds potential to be used as a
means to control that insect. See also 
B
.
t
.
KURSTAKI
,
HELIOTHIS VIRESCENS
  (
H
.
VIRESCENS
),
FUNGUS
,
PECTINOPHORA GOSSYPIELLA
,
ASPERGILLUS
FLAVUS
,
CORN
,
MONOCLONAL ANTIBODIES
 (
MA
b
).
Heliothis virescens (H. virescens) Known as
the tobacco budworm (when it is on tobacco
plants), this is one of three insect species that
is called “bollworms” (when they are on cot-
ton plants). As part of Integrated Pest Man-
agement (IPM), farmers can utilize the
parasitic Euplectrus comstockki wasp to help
control the tobacco budworm/cotton boll-
worm. When that wasp’s venom is injected
into Heliothis larva, it stops the larva from
molting (and thus maturing). See also 
B
.
t
.
KURSTAKI
,
HELICOVERPA ZEA
  (
H
.
ZEA
),
PECTINO-
PHORA GOSSYPIELLA
,
INTEGRATED PEST MANAGE-
MENT
 (
IPM
).
Helix A spiral, staircase-like structure with a
repeating pattern described by two simulta-
neous operations (rotation and translation).
It is one of the natural conformations exhib-
ited by biological polymers. See also 
BIOMI-
METIC MATERIALS
,
ANALOGUE
.
Helper T Cells (T4 cells) T cells (lympho-
cytes) which bind B cells (upon recognizing
a foreign epitope on B cell surface). The
binding stimulates B cell proliferation by
secreting B cell growth factor. See also
B CELLS
,
CYTOKINES
,
T CELL
,
T CELL RECEPTORS
,
SUPPRESSOR T CELLS
.
Hemagglutinin (HA) A special protein that
some viruses utilize to gain entry into the cells
they have “targeted.” The HA protein helps
the virus adhere to the cell it targets. Hemag-
glutinin is also utilized to refer to specific plant
cell proteins (lectins) that are naturally pro-
duced by certain plants such as the soybean
plant (Glycine max (L) Merrill). The presence
of those lectin molecules (e.g., on surfaces of
root cells of the soybean plant) help nitrogen-
fixing Rhizobium japonicum bacteria to
adhere to soybean plant roots, where they
begin to “fix nitrogen” (i.e., create natural
nitrate fertilizer, which improves the soil and
helps plants to grow). See also 
PROTEIN
,
VIRUS
,
CELL
,
LECTINS
,
SOYBEAN PLANT
,
NITROGEN FIXA-
TION
,
BACTERIA
,
NITRATES
,
NODULATION
.
Hematologic Growth Factors (HGF) A class
of colony stimulating factors (proteins) that
stimulates bone marrow cells to produce cer-
tain types of red and white blood cells. Some
colony stimulating factors are:
1. Granulocyte-macrophage colony stim-
ulating factor (GM-CSF)
2. Granulocyte-monocyte colony stimu-
lating factor
3. Granulocyte colony stimulating factor
(GM-CSF)
4. Erythropoietin (EPO)
5. Interleukin-3 (IL-3)
6. Macrophage colony stimulating factor
(M-CSF)
Hematopoietic Growth Factors Growth fac-
tors that stimulate the body to produce blood
cells. See also 
GROWTH FACTOR
,
INTERLEUKIN-
6
(
IL-
6
).
© 2002 by CRC Press LLC

H
Hematopoietic Stem Cells Certain stem cells
present (e.g., in infants’ bodies, and in the
umbilical cords of newborn infants), that can
be differentiated (via chemical signals in the
growing body) to give rise to red blood cells
and the infection-fighting cells of the
immune system. See also 
STEM CELLS
,
MULTI-
POTENT ADULT STEM CELLS
,
MESODERMAL ADULT
STEM CELLS
,
CELL
,
ORGANISM
,
SIGNALING
.
Heme The iron-porphyrin prosthetic group of
a class of proteins called “heme proteins.”
See also 
PROSTHETIC GROUP
,
CHELATING AGENT
,
PROTEIN
,
TRANSFERRIN
.
Hemoglobin An oxygen-transporting respira-
tory pigment; it is present in humans, ani-
mals, and some plants (e.g., land plants that
withstand occasional immersion/flooding).
In humans, hemoglobin is carried in the red
blood cells (erythrocytes), and is responsible
for the red color of the blood. It is composed
of two pairs of identical polypeptide chains
and iron-containing heme groups, compris-
ing the (total) hemoglobin molecule. The
molecular structure of hemoglobin was
determined by Max Perutz in 1959. A human
disease known as sickle-cell anemia is caused
by a (genetically induced) small change in the
hemoglobin molecule’s structure (in victims
of that disease). See also 
HEME
,
POLYPEPTIDE
(
PROTEIN
),
GENETICS
,
BILIRUBIN
,
HEREDITY
,
ERYTHROCYTES
,
PROTEIN STRUCTURE
.
Hemostasis See
FIBRIN
.
Heparin A polysaccharide sulfuric acid ester
found in the liver, lung, and other tissues that
prolongs the clotting time of blood by pre-
venting the formation of fibrin. Used in vas-
c u l a r   s u rg e r y   a n d   i n   t r e a t m e n t   o f
postoperative thrombosis and embolism. See
also
FIBRIN
,
THROMBOSIS
.
HER-2 Gene Abbreviation for Human Epi-
dermal growth factor Receptor-2 gene, an
oncogene that is responsible for approxi-
mately 30% of breast cancers (i.e., in those
women whose body over-expresses that par-
ticular oncogene, and it spreads via meta-
staticism). In addition to conventional
treatments (mastectomy, chemotherapy, etc.),
the U.S. Food and Drug Administration (FDA)
in 1998 approved use of a humanized mono-
clonal antibody (trastuzumab) to be utilized
alone, or in combination with, certain chemo-
therapy agents (e.g., paclitaxel) against such
metastatic breast cancers. That monoclonal
antibody attaches to the extracellular domain
(i.e., portion of the Her-2 receptor sticking out
of the surface of breast tissue cells) and down-
regulates the Her-2 gene, i.e., resulting in
fewer Her-2 receptors being produced on the
plasma membrane surfaces of that woman’s
breast tissue cells. See also 
GENE
,
RECEPTORS
,
HER
-2
RECEPTOR
,
RAS GENE
,
EGF RECEPTOR
,
ONCO-
GENES
,
CANCER
,
EXPRESS
,
EXPRESSIVITY
,
MONO-
CLONAL ANTIBODIES
  (
MA
b
),
B R C A G E N E S
,
PACLITAXEL
,
FOOD AND DRUG ADMINISTRATION
(
FDA
),
PLASMA MEMBRANE
.
HER-2 Protein See
HER
-2
RECEPTOR
.
HER-2 Receptor An epidermal growth factor
receptor (protein molecule embedded in the
surface of cells) that is present in abundance
attached to the plasma membrane surface of
breast tissue cells in humans possessing the
HER-2 gene. See also 
RECEPTORS
,
EPIDERMAL
GROWTH FACTOR RECEPTOR
,
PLASMA MEMBRANE
,
HER
-2
GENE
.