Biotechnology

Particle Cannon See
BIOLISTIC R GENE GUN
,
MICROPARTICLES
.
© 2002 by CRC Press LLC

P
Particle Gun See
BIOLISTIC
®
GENE GUN
,
MICRO-
PARTICLES
, “
SHOTGUN
”
METHOD
.
Partition Coefficient A constant (number)
that expresses the ratio in which a given
solute will be partitioned (distributed)
between two given immiscible liquids (e.g.,
oil and water) at equilibrium.
Partitioning Agent Any one of a number of
chemical compounds (e.g., certain hor-
mones, conjugated fatty acids, etc.) which
cause a given animal’s metabolism to deposit
significantly more lean muscle tissue and
significantly less fat tissue within that (grow-
ing) animal’s body. See also 
BOVINE SOMA-
TOTROPIN
  (
BST
),
PORCINE SOMATOTROPIN
  (
PST
),
CONJUGATED LINOLEIC ACID
  (
CLA
),
CARNITINE
,
METABOLISM
,
FATS
.
Passive Immunity An immune response (to a
pathogen) that results from injecting another
organism’s antibodies into the organism that
is being challenged by the pathogen. See
also
POLYCLONAL ANTIBODIES
,
HUMORAL IMMU-
NITY
,
ANTIBODY
,
COMPLEMENT
,
COMPLEMENT
CASCADE
,
IMMUNOGLOBULIN
,
PATHOGEN
,
ANTI-
GEN
,
MONOCLONAL ANTIBODIES
 (
MA
b
).
PAT Gene A dominant gene isolated from the
Streptomyces viridochromogenes bacterium
which codes for (causes production of) the
enzyme phosphinothricin acetyl transferase
(PAT). When the PAT gene is inserted into a
plant’s genome, it imparts resistance to glufo-
sinate-ammonium containing herbicides.
Because the glufosinate-ammonium herbi-
cides act via inhibition of glutamine syn-
thetase (an enzyme that catalyzes the synthesis
of glutamine), this inhibition of enzyme kills
plants (e.g., weeds). That is because glutamine
is crucial for plants to synthesize critically
needed amino acids. The PAT gene is also
often used by genetic engineers as a marker
gene. See also 
GENE
,
GENOME
,
GENETIC ENGI-
NEERING
,
MARKER
 (
GENETIC MARKER
),
BAR GENE
,
DOMINANT ALLELE
,
ESSENTIAL AMINO ACIDS
,
HER-
BICIDE
-
TOLERANT CROP
,
GTS
,
SOYBEAN PLANT
,
CANOLA
,
CORN
,
GLUTAMINE
,
GLUTAMINE SYN-
THETASE
,
PHOSPHINOTHRICIN
,
PHOSPHINOTHRICIN
ACETYLTRANSFERASE
 (
PAT
).
Pathogen Refers to a virus, bacterium, para-
sitic protozoan, or other microorganism that
causes infectious disease by invading the
body of an organism (animal, plant, etc.)
known as the host. It should be noted that
infection is not synonymous with disease
because infection does not always lead to
injury of the host. See also 
VIRUS
,
BACTERIA
,
PROTOZOA
,
MICROORGANISM
,
STRESS PROTEINS
,
ANTIGEN
,
IMMUNE RESPONSE
,
PHYTOALEXINS
,
PATHOGENESIS RELATED PROTEINS
.
Pathogenesis Related Proteins P r o t e c t i v e
(i.e., disease-fighting) proteins that are pro-
duced within certain plants in response to
the entry-into-plant of plant pathogens (bac-
teria, fungi, etc. that infect and cause disease
in plants). One pathogenesis-related protein
is chitinase, a protein enzyme that degrades
(breaks down) the chitin within cell walls of
pathogenic fungi. Production of pathogene-
sis-related proteins is often initiated by sig-
naling molecules (e.g., harpin) produced by
the pathogens. See also 
PROTEIN
,
PATHOGEN
,
BACTERIA
,
FUNGUS
,
CHITINASE
,
CHITIN
,
CELL
,
ENZYME
,
SIGNALING
,
SIGNALING MOLECULE
,
HARPIN
,
HYPERSENSITIVE RESPONSE
.
Pathogenic Disease-causing. See also 
PATHOGEN
.
Pathway A sequential series of chemical reac-
tions, each of which is dependent on previ-
ous ones in the pathway (e.g., the third
reaction requires chemical product produced
by first/second chemical reactions), that —
overall — yields a beneficial impact. For
example, metabolism (i.e., the entire set of
enzyme-catalyzed chemical reactions which
converts food into nutrients that can be used
by the body’s cells and the use of these nutri-
ents by the body’s cells to sustain life, grow,
etc.) occurs via a very specific
METABOLIC
PATHWAY
. See also 
METABOLISM
,
ACC SYNTHASE
,
R GENES
,
PATHWAY FEEDBACK MECHANISMS
.
Pathway Feedback Mechanisms Chemically
based mechanisms (e.g., series of chemical
reactions) that hinder (or increase rate of) a
given pathway. For example, when the body
of bacteria need catabolism (i.e., energy pro-
duction) to be slowed down, it uses the
mechanism of catabolite repression (to slow
down catabolism via chemical/reaction
means). See also 
PATHWAY
,
METABOLISM
,
CATABOLISM
,
CATABOLITE REPRESSION
.
PBR The intellectual property rights that are
legally accorded to plant breeders by laws,
treaties, etc. Similar to patent law for inven-
tors. See also 
PLANT BREEDER
’
S RIGHTS
 (
PBR
),
© 2002 by CRC Press LLC

P
PLANT
’
S NOVEL TRAIT
  (
PNT
),
PLANT VARIETY
PROTECTION ACT
 (
PVP
),
EUROPEAN PATENT CON-
VENTION
,
EUROPEAN PATENT OFFICE
  (
EPO
),
U
.
S
.
PATENT AND TRADEMARK OFFICE
 (
USPTO
).
pBR322 An Escherichia coli (E. coli) plasmid
cloning vector that contains the ampicillin
resistance and tetracycline resistance genes.
It consists of a circle of double-stranded
DNA. See also 
E S C H E R I C H I A
C O L I F O R M
(
E
.
COLI
),
PLASMID
,
VECTOR
,
DEOXYRIBONUCLEIC
ACID
 (
DNA
).
PC Phosphatidyl choline. See also 
LECITHIN
(
refined, specific
),
LECITHIN
 (
crude, mixture
).
PCR See
POLYMERASE CHAIN REACTION
 (
PCR
).
PDCAAS See
PROTEIN DIGESTIBILITY
-
CORRECTED
AMINO ACID SCORING
 (
PDCAAS
).
PDE See
PHOSPHODIESTERASES
.
PDGF See
PLATELET
-
DERIVED GROWTH FACTOR
(
PDGF
).
PDWGF See
PLATELET
-
DERIVED WOUND GROWTH
FACTOR
 (
PDWGF
).
Pectinophora gossypiella Also known as the
pink bollworm, this is one of three insect
species that are called “bollworms” (when
they are on cotton plants). The holes that
they chew in cotton plants’ bolls have been
shown to enable the Aspergillas flavus fun-
gus to infect those (chewed) cotton plants.
See also 
B
.
t
.
KURSTAKI
,
HELICOVERPA ZEA
 (
H
.
ZEA
),
HELIOTHIS VIRESCENS
,
BRIGHT GREENISH
-
YELLOW
FLUORESCENCE
 (
BGYF
).
PEG-SOD (polyethylene glycol superoxide
dismutase) A modified version of the
enzyme human superoxide dismutase
(hSOD), in which polyethylene glycol (a
polymer made up of ethylene glycol mono-
mers) is combined with the hSOD molecule.
The PEG seems to wrap around or about the
enzyme in such a way that the whole com-
plex is able to exist in the blood for longer
periods of time than the unmodified hSOD
enzyme. This is because the PEG effectively
camouflages the hSOD molecule and hence
protects it from being inactivated by the
body’s own defense mechanisms in the
bloodstream. This technology is important
in that hSOD is used to fight certain diseases
by injecting it into the body. However, the
SOD must be present in the body for
extended periods of time in order to effec-
tively work, and since the injected SOD is a
foreign molecule, the body tries to destroy
it (and hence its function) as quickly as pos-
sible. See also 
HUMAN SUPEROXIDE DISMUTASE
(
h
SOD
),
CATALASE
,
ENZYME
.
Penicillin G (benzylpenicillin) The original
penicillin (antibiotic) molecule, discovered
by Alexander Fleming in 1928, in a petri dish
(experiment) ‘spoiled’ by accidental intro-
duction of a mold. Fleming named the anti-
biotic after the particular mold (Penicillium
notatum) that had produced it. During the
1940s, scientists at the U.S. Department of
Agriculture in Peoria, Illinois (in the U.S.),
discovered how to produce commercial
quantities of Penicillin G by utilizing the
fungus Penicillium chrysogenum, which they
found growing on a canteloupe in Peoria.
Penicillin kills bacteria by blocking an
enzyme which is crucial to growth and repair
of the bacteria’s cell wall (peptidoglycan
layer), but penicillin does not harm other
species, so it is species-specific to certain
pathogenic bacteria (e.g., streptococcus,
meningococcus, and diphtheria bacillus).
See also 
ANTIBIOTIC
,
FUNGUS
,
BACTERIA
,
ENZYME
,
SPECIES SPECIFIC
,
PENICILLIUM
,
BETA
-
LACTAM ANTIBIOTICS
,
BACILLUS
.
Penicillinases (E.C. 3.5.2.6) Also known as
β-lactamases, these are enzymes that hydro-
lyze (break down) the 
β-lactam ring (por-
tion) of the penicillin molecule’s structure.
Some microorganisms (e.g., pathogenic bac-
teria) have become able to produce these
enzymes as a defense to penicillin and ceph-
alosporin antibiotics (drugs). See also
ENZYME
,
HYDROLYZE
,
PENICILLIN G
 (
BENZYLPEN-
ICILLIN
),
PATHOGENIC
,
BACTERIA
,
ANTIBIOTIC
,
ANTIBIOTIC RESISTANCE
.
Penicillium Refers to the genus of fungi
(mold) that belongs to the category Deutro-
mycotina and often causes (food) spoilage.
Some of the genus have been utilized com-
mercially to produce antiboiotics. See also
GENUS
,
FUNGUS
,
OCHRATOXINS
,
ANTIBIOTIC
,
PEN-
ICILLIN G
 (
benzylpenicillin
).
Pentose A simple sugar (monosaccharide mol-
ecule) whose backbone structure contains
five carbon atoms. There exists many differ-
ent pentoses. Some examples of pentoses are
ribose, arabinose, and xylose. See also
MONOSACCHARIDES
.
© 2002 by CRC Press LLC

P
Pepsin A crystallizable proteinase (enzyme)
that in an acidic medium digests (breaks
down) most proteins to polypeptides. It is
secreted by glands in the mucous membrane
of the stomach of higher animals. In combi-
nation with dilute hydrochloric acid, it is the
chief active principle (component) of gastric
juice. Also used in manufacturing peptones
and in digesting gelatin for the recovery (i.e.,
recycling) of silver from photographic film.
See also 
DIGESTION
 (
WITHIN ORGANISMS
),
PRO-
TEIN
,
PEPTIDE
,
LACTOFERRIN
,
PEPTONE
.
Peptidase A n   e n z y m e   t h a t   h y d r o l y z e s
(cleaves) a peptide bond. See also 
PEPTIDE
BOND
,
PEPSIN
,
PEPTONE
,
PEPTIDE MAPPING
(“
FINGERPRINTING
”).
Peptide Two or more amino acids covalently
joined by peptide bonds. An oligomer com-
ponent of a polypeptide. A dipeptide, for
example, consists of two (di) amino acids
joined together by a peptide bond or linkage.
By analogy, this structure would correspond
to two joined links of a chain. See also
POLYPEPTIDE
 (
PROTEIN
),
OLIGOMER
,
AMINO ACID
.
Peptide Bond A covalent bond (linkage)
between the 
α-amino group of one amino
acid and the 
α-carboxyl group of another
amino acid. This is the linkage or bond
which holds the amino acids (chain links)
together in a polypeptide chain. It is the all-
important bond which holds the amino acid
monomers together to form the polymer
known as a polypeptide. See also 
PEPTIDE
,
POLYPEPTIDE
 (
PROTEIN
),
OLIGOMER
.
Peptide Mapping (fingerprinting) Refers to
the characteristic pattern of peptides (i.e.,
pieces that make up a protein molecule)
resulting from partial hydrolysis (cleavage,
digestion) of a protein. The pattern (finger-
print) is obtained by separating the peptides
via two-dimensional chromatography, in
which the peptides are first subjected to
chromatography using one solution which
separates many, but not all, peptides. The
chromatogram is then turned 90°, and is
again chromatographed using a second solu-
tion, which then separates all of the peptides;
thereby producing the final “fingerprint” of
the protein. See also 
CHROMATOGRAPHY
,
PEPTIDE
,
PROTEIN
,
HYDROLYSIS
.
Peptide Nanotube See
SELF
-
ASSEMBLY
  (
OF A
LARGE MOLECULAR STRUCTURE
).
Peptido-Mimetic See
BIOMIMETIC MATERIALS
,
PEPTIDE
.
Peptone A protein that has been partially hydro-
lyzed (cleaved) by the peptidase pepsin. See
also
PROTEIN
,
HYDROLYTIC CLEAVAGE
,
PEPTIDASE
,
PEPSIN
,
PEPTIDE MAPPING
 (“
FINGERPRINTING
”).
Perforin A 70 Kd (kilodalton) protein that is
instrumental in the lysis of infected cells. A
series of reactions occurs on the surface of
a cell which results in the polymerization of
certain monomers to form transmembrane
(through the membrane) pores 100 Å (Ang-
stroms) wide, which allows ions to rush into
the cell (due to osmotic pressure) and thus
burst (lyse) that cell, so the (formerly) inter-
nal pathogens can be attacked by the body’s
immune system. Perforin is a protein that is
akin to the C9 component of the comple-
ment. See also 
OSMOTIC PRESSURE
,
COMPLE-
MENT
,
COMPLEMENT CASCADE
,
K
d
,
CYTOTOXIC
T CELLS
,
CECROPHINS
,
MAGAININS
,
OSMOTINS
.
Periodicity The number of base pairs per turn
of the DNA double helix. See also 
DEOXY-
RIBONUCLEIC ACID
 (
DNA
).
Periodontium Tissue that anchors teeth in the
jaw. Regrowth of periodontal tissue can be
stimulated by a combination of platelet-
derived growth factor and insulin-like
growth factor-1. See also 
PLATELET
-
DERIVED
GROWTH FACTOR
  (
PDGF
),
INSULIN
-
LIKE GROWTH
FACTOR
-
1
 (
IGF
-
1
).
Peritoneal Cavity/Membrane The smooth,
transparent, serous membrane that lines the
cavity of the abdomen of a mammal.
Peroxidase An enzyme that catalyzes the oxi-
dation of a substrate with hydrogen peroxide
(as the electron acceptor, so the hydogen
peroxide is reduced). Peroxidase is naturally
produced in soybeans by approximately half
of all commercial soybean varieties. Perox-
idase very effectively inhibits (stops) growth
of any Aspergillus flavus fungi that might be
present (e.g., in the soil). Peroxidase can be
used to replace more toxic and environmen-
tally problematic chemicals in certain indus-
trial processes. Among other applications,
peroxidase can replace formaldehyde use in
paints, varnishes, glues, and computer chip
manufacturing. See also 
ENZYME
,
OXIDIZING
© 2002 by CRC Press LLC

P
AGENT
  (
OXIDANT
),
OXIDATION
,
SUBSTRATE
(
CHEMICAL
),
OXIDATION
-
REDUCTION REACTION
.
Persistence The tendency of a compound (e.g.,
an insecticide) to resist degradation by bio-
logical means (e.g., metabolism by microor-
ganisms) after that compound has been
introduced into the environment (e.g.,
sprayed onto a field) or by physical means
(degradation caused by exposure to sunlight,
moisture, etc.). See also 
METABOLISM
,
MICRO-
ORGANISM
,
BIODEGRADABLE
.
Pfiesteria piscicida A single-celled micro-
scopic algae which has a predator/prey rela-
tionship with fish in its ecosystem. During a
large portion of its life cycle, Pfiesteria pis-
cicida exists in a nontoxic cyst form at the
bottom of a river. When those (cysts) detect
certain substances (e.g., excreta) emitted by
live fish, the Pfiesteria piscicida transform
into an amoeboid or dinoflagellate form,
which secretes a water-soluble neurotoxin
into the water (which incapacitates nearby
fish). The Pfiesteria piscicida next attach
themselves to those fish, and excrete a lipid-
soluble toxin which destroys the epidermal
layer of the fish’s skin, allowing the Pfieste-
ria piscicida to begin “eating” the fish’s tis-
sue. Human exposure to the neurotoxin
apparently causes short-term memory loss.
See also 
ECOLOGY
,
CELL
,
TOXIN
,
LIPIDS
.
PHA See
POLYHYDROXYALKANOIC ACID
 (
PHA
).
Phage Abbreviation for bacteriophage.
Another name for a specific type of virus. A
virus that attacks bacteria is known as a bac-
teriophage. Bacteriophages are frequently
used as vectors for carrying (foreign) DNA
into cells by genetic engineers. See also 
BAC-
TERIOPHAGE
,
VECTOR
,
GENETIC ENGINEERING
,
TRANSFECTION
,
DEOXYRIBONUCLEIC ACID
 (
DNA
).
Phagocyte A cell such as a leukocyte that
engulfs and digests cells, cell debris, micro-
organisms, and other foreign bodies in the
bloodstream and tissues (phagocytosis). The
ingested material is then degraded via
enzymes. A whole class of cells is known to
be phagocytic. See also 
MACROPHAGE
,
MICROPHAGE
,
MONOCYTES
,
T CELLS
,
POLYMOR-
PHONUCLEAR LEUKOCYTES
  (
PMN
),
CELLULAR
IMMUNE RESPONSE
,
POLYMORPHONUCLEAR GRAN-
ULOCYTES
,
LYSOSOME
.
Pharmacoenvirogenetics A word coined dur-
ing 2000 by Tim Studt to describe the fact
that environmental factors interact with a
given individual’s (human/animal/plant)
genetic makeup (i.e., genome) to determine
those individual’s (body’s) response to a
given pharmaceutical (and/or progression of
a disease). Those environmental factors
include:
• Foods eaten
• The stress the individual is exposed to
• Air and water pollution the individual
is exposed to
• Temperature and humidity the individ-
ual is exposed to
• Geographical elevation the individual is
exposed to
• Bacteria the individual is exposed to
For example, when Rhizobium japonicum
bacteria grow in the soil near the roots of a
soybean plant (Glycine max L.), that causes
certain specific genes in the soybean plant to
be expressed (i.e., “turned on”) so that soy-
bean plant’s roots become more hospitable
as a “home” for those Rhizobium japonicum
bacteria to live symbiotically (in nodules on
the roots) with the soybean plant. See also
PHARMACOKINETICS
,
GENETICS
,
PHARMACOLOGY
,
PHARMACOGENETICS
,
ABSORPTION
,
METABOLISM
,
SNP
,
ALLELE
,
HAPLOTYPE
,
HAPTOGLOBIN
,
RHIZO-
BIUM
 (
BACTERIA
),
NODULATION
,
SYMBIOTIC
,
CEN-
TRAL DOGMA
 (
NEW
),
ACCLIMATIZATION
.
Pharmacogenetics A branch of pharmacoki-
netics that deals with the reactions between
drugs, or free radicals, or synthetic food
ingredients, and specific individuals due to
the genetics of those individuals. The sub-
group of all those individuals whose DNA
causes their bodies to respond in a specific
way to a given drug or synthetic food ingre-
dient, is known as a 
HAPLOTYPE
. For example,
one haplotype (subgroup) of pediatric leuke-
mia patients suffers severe and life-threaten-
ing reactions to some commonly used
leukemia treatment drugs, due to the varia-
tion (i.e., SNP) in the thiopurine S-methyl
transferase gene (allele) in their genome.
Another example is that consumption of
© 2002 by CRC Press LLC

P
sodium-containing food ingredients tends to
cause a dangerous increase in blood pressure
(hypertension) among the African-American
people living in the U.S., more often than
among other ethnic groups living in the U.S.
See also 
PHARMACOKINETICS
,
PHARMACOGENOM-
ICS
,
GENETICS
,
PHARMACOLOGY
,
ABSORPTION
,
METABOLISM
,
HAPLOTYPE
,
DEOXYRIBONUCLEIC
ACID
  (
DNA
),
MUTATION
,
SNP
,
ALLELE
,
CANCER
,
HAPTOGLOBIN
,
TRANSVERSION
.
Pharmacogenomics A branch of pharmacoki-
netics that deals with the biological impacts
of pharmaceuticals or synthetic food ingre-
dients, and the specific differences in
response/reaction of living structures (tis-
sues, organs, etc.) due to different genomes
(DNA) of those individual organisms that
consume those pharmaceuticals or food
ingredients. The subgroup consisting of all
those individuals whose genome (DNA)
causes their body to respond in a specific way
to a given pharmaceutical, free radical, or
synthetic food ingredient, is known as a 
HAP-
LOTYPE
. A haplotype could (theoretically) be
as small as one individual (e.g., one woman,
possessing an as yet unknown genome),
because that woman’s particular specific
response to a pharmaceutical could result
from one single-nucleotide polymorphism
(SNP) that only her genome possesses. Thus,
pharmacogenomics is the pharmacokinetics
(of a given pharmaceutical or food ingredi-
ent) within a specific haplotype.
For example, some ethnic minorities,
genders, and individuals have far different
biological reactions/responses to certain
pharmaceuticals (e.g., the painkiller mor-
phine works better in women, aspirin “thins”
men’s blood better than women’s blood, the
painkiller ibuprofen works better in men, the
diuretic drug thiazide works to control
hypertension in 60% of U.S. African Amer-
icans but only 8% of U.S. Caucasian people,
etc.), and food ingredients (e.g., monosodium
glutamate, lactase, ethanol, etc.) impact some
members of some ethnic minorities more
than they do the majority of humans. That is
due to the fact that different gene(s) within
their genomes (DNA) cause synthesis of cer-
tain different proteins (generally enzymes),
which thereby cause the tissues/bodies of
those individuals/ethnic minorities to react
differently to specific pharmaceuticals or
food ingredients in terms of:
• Absorption — transport of the drug
(pharmaceutical) or food ingredient into
the bloodstream (e.g., from the intesti-
nal tract, in the case of food ingredients
or orally administered drugs).
• Distribution — initial physical disposi-
tion/behavior of the substance in the
body after the substance enters the body
tissues. For example, does the sub-
stance preferentially concentrate in the
fat cells (adipose tissue) of the body, or
in other specific tissues?
• Metabolism — breakdown of the sub-
stance (if breakdown does occur) into
other chemical compounds, and the
ultimate disposition in the body of
those compounds (or the original sub-
stance, if breakdown does not occur).
• Elimination — the speed and thorough-
ness with which the substance is
excreted or is otherwise removed from
the body.
See also 
PHARMACOKINETICS
,
GENOMICS
,
PHAR-
MACOLOGY
,
ADME TESTS
,
ABSORPTION
,
METABO-
LISM
,
GENOME
,
DEOXYRIBONUCLEIC ACID
 (
DNA
),
DIGESTION
  (
WITHIN ORGANISMS
),
PHASE I CLINI-
CAL TESTING
,
HAPLOTYPE
,
CONSENSUS SEQUENCE
,
PHARMACOGENETICS
,
GENE
,
ALLELE
,
SINGLE
-
NUCLEOTIDE POLYMORPHISMS
  (
SNP
s
),
PROTEIN
,
ENZYME
,
HAPTOGLOBIN
,
ADIPOSE
.