| P
~P: a symbol for a high-energy phosphate bond.
P site: positively-charged site.
ρ-value:
ρ is Greek alphabet for r and pronounced rho like in row. See
under r section.
paraldehyde: a colorless liquid polymeric modification of
acetaldehyde used as a hypnotic.
para-substitution: In a six-membered aromatic nucleus of say,
phenol molecule, a substitution of the H atom on the carbon atom that
are separated from the OH-bearing carbon atom by two carbon atoms is
called a para-substitution. A substitution on the carbon atom
separated from the OH-bearing carbon atom by one carbon atom is called a
meta-substitution. A substitution on the carbon atom immediately
next to the OH-bearing carbon atom is called an ortho-substitution.
pari passu: Latin at an equal rate or pace.
partial molar volume: In a mixture of n1
moles of substance 1 and n2 moles of substance 2, the volume
of the mixture is V, and V = n1 V1 + n2
V2 where V1 is the partial molal volume of
substance 1 and V2 is the partial molal volume of substance
2.
partially resonating structure: The C-N bond of a polypeptide
chain resonates between 60% single bond and 40% double bond structure
but the C-C bond is a simple single bond. Therefore as a whole, the
polypeptide chain is a partially resonating structure.
partial vapor pressure: According to Dalton's Law of partial
pressure, the total pressure of a mixture of gases is equal to the sum
of the partial pressure of the constituent gases. The partial pressure
is defined as the pressure each gas would exert if it alone occupies the
whole volume of the mixture at the same temperature. Thus the partial
vapor pressure is the pressure of water vapor in a mixture of water
vapor and the gases of the air.
partition coefficient: the true equilibrium distribution
coefficient.
patent system: an official system which offers to an inventor for
a term of years the exclusive right to make, use or sell his or her
invention.
PCG electrode: short for polylysine-treated collodion-coated
glass electrode.
peer review system: a system to evaluate the merit of scientific
work or a scientist by a panel of peers and relies on their majority
opinion to award or deny.
PEG: poly(ethylene glycol), H(OCH2CH2)nОН,
а large water-soluble oxygen-containing polymer.
PEG-8000: PEG with an average molecular weight of 8000.
PEG-4000: short for poly(ethylene glycol) with an average
molecular weight of 4000.
PEI: poly (ethylene imine), (CH2NHCH2)n,
a large water soluble, nitrogen-containing polymer.
pentose: various monosaccharides that contain five carbon atoms
in the molecules Examples, D-xylose.
PEO: poly(ethylene oxide), (CH2OCH2)n,
a large water-soluble polymer.
peptide bond: the chemical bond between the carbon and nitrogen
atom of a peptide linkage.
peptide linkage: the CONH group that unites the amino acid
residues in a peptide.
perfect gas: also known as ideal gas, defined as a gas to which
the Laws of Boyle, Gay-Lussac, and Avogadro are applicable at all
temperatures.
perfused dog gastrocnemius muscle: After cannulating the blood
vessels supplying the dog gastrocnemius muscle, a Ringer-Locke solution
is used to perfuse the muscle so that the gain and loss of K+
during tetanic contraction of the muscle could be determined from
aliquots of the perfusate.
permanent dipole moment: A molecule like H20, due to
the asymmetric location of the two positively charged H atoms, is
positive on one end and negative on the other end, and for this reason,
it possesses a permanent dipole moment.
permeability: the specific property of a membrane or surface
which determines the rate of entry or exit of a particular ion or
molecule.
permeant: being able to permeate.
permittivity: a scalar quantity
ε defined by D =
ε E, where D is the (vector electric)
displacement and E, the (vector electric) field intensity.
The more familiar dielectric constant of a substance is a relative
constant, equal to the permitivity of that substance divided by the
permitivity of free space.
Permutite: a silicate which acts as an ion exchanger and used as
a water softener, giving off Na+ in exchange for Ca2+
or Mg2+.
pH: the negative logarithm of the hydrogen ion concentration.
pharmacology: the science of drugs including materia medica,
toxicology and therapeutics.
pharmacon: a drug.
phase transition: The change of liquid water into steam or that
of liquid water into solid ice exemplifies the discontinuous changes
occurring in a narrow range of temperature called phase transitions. It
was recognized early that this type of discontinuous change occurs only
in condensed systems and it arises from interaction among large number
of the microscopic component(s) of the system. Phase transitions are
cooperative phenomena.
phase-boundary potential: the steady electric potential
difference across the boundary of two contiguous phases.
phenol group: a hydroxyl group on an aromatic ring, e.g., the OH
group of phenol.
phenylalanine: a common a-amino acid found in most protein
hydrolysates.
phloem: a complex system in the vascular system in higher plants
which is engaged in translocation and in support and storage.
phlogiston: a hypothetical substance presumed to exist in all
combustible materials and it is liberated from the material during
burning.
phospholipase a (lecithinase a): an enzyme which hydrolyzes the (β-ester
bond of zwitterionic glycophospholipids This enzyme is found in cobra
venom.
phospholipid bilayer: When a solution of phospholipids in a
chloroform-methanol mixture is painted over a loop and the loaded loop
then immersed in a salt solution, dispersion of the solvent into the
medium eventually thins out the membrane into a bimolecular layer,
called phospholipid bilayer.
phospholipid bilayer theory of cell membranes: a theory according
to which a phospholipid bilayer forms the continuous phase of all cell
membranes.
photoemulsion: a suspension of photosensitive silver salt in a
viscous medium (e.g., gelatin solution) It can be applied as a coating
onto glass plates carrying specimen "stained" with radioactive materials
as in autoradiography.
photon: a quantum of radiant energy.
physiological activities: normal activities of living cells and
aggregates of cells.
pinwheel type of triplet route: When an entrant cation, say Rb+,
is strongly adsorbed on the fixed anionic site on the cell surface, its
entry into the cell is very slow unless it is facilitated by the
participation of a second cation, say K+, whose approach to
the fixed anion-Rb+ pair lowers the activation energy for the
desorption of the Rb+ and entry into the cell. If the
activating cation, K+, comes from inside the cell, this
triplet route is called the pinwheel type. On the other hand, if the
activating K+ comes from the same side the entrant Rb+
came from, namely the outside, the triplet route is called the billiard
type. For clarity, only cation entry into the cell is discussed. But the
same principle applies to exit of free cation (or even free anion) from
the cell as well. (For diagrammatic illustrations, see Fig. 36.)
pith: loose spongy tissue occupying the center of the stem of
dicotyledonous plants.
pK: the negative logarithm of the acid dissociation constant К of
an acid or base. See acid dissociation constant.
pKa: same as pK as used in this volume.
pK determination from titration curve: To determine the pK of an
unknown acid, one mixes equal volumes of solutions containing a fixed
(rather small) amount of the unknown acid and a varying amount of an
acid of known concentration. And measure the pH of each of the solutions
after equilibrium has been reached. Plotting the amount of acid (as
ordinate) against the pH (as abscissa) one obtains the titration (or
neutralization) curve of the unknown acid. Now, according to the
equation of L.J. Haldane,13 p 1003 pH = pK + log
([salt]/[acid]), where [salt] and [acid] represent respectively the
concentration of the acid that has been neutralized (and thus turned
into "salt") and the acid that has not been neutralized yet (and thus
remains as acid). At the mid-point of the titration curve, [salt] and
[acid] are equal (their ratio equal to unity). Since logarithm of one is
zero, the pH corresponding to the midpoint of the titration curve is
equal to the pK of the acid.
plasma membrane: same as Plasmahaut or cell membrane.
Plasmahaut: the name Wilh. Pfeffer offered in 1877 for what is
now called cell membrane Literally it means protoplasmic skin.
PM theory: acronym of the polarized multilayer theory of cell
water and model systems.
polarizability: the dipole moment produced by a unit electric
field acting on a molecule In the absence of permanent dipoles, the
polarizability of a molecule is the sum of separate electronic
polarizabilities of its constituent atoms with slight corrections due to
the bond structure. When a moment in is induced by a field of intensity,
F, the polarizability of the molecule,
α, is equal to m/F.
polarization: The total polarization of a molecule possessing a
permanent dipole moment (as in water), is the sum of two terms.
One, sometimes called distortion polarization, arises from the
electric polarization or induction. The other, sometimes called
orientation polarization, arises from the orientation of the permanent
dipole.
polarization theory, de Boer-Zwikker polarization theory: a
theory of multilayer polarization and condensation of noble gas and
other molecules on solid surface presenting a checkerboard of positively
and negatively charged sites by de Boer and Zwikker {For more details,
see [11.2].}
polarized multilayer theory of cell water (PM theory): theory of
cell water and model systems introduced by Ling in 1965 as part of the
association-induction hypothesis.
polyacrylic acid, poly(acrylic acid): [-CH2CH(COOH)-]n.
polyatomic molecules: molecules containing many atoms.
polyethylene glycol, poly(ethylene glycol), PEG: Н(ОСН2СН2)nОН,
a water soluble polymer with average molecular weight ranging from 200
to 10,000. PEG-4000, for example, refers to poly(ethylene glycol) with
average molecular weight of 4000.
poly(ethylene oxide), PEO, Polyox: (-CH2CH2O-)n,
a water soluble polymer.
polyethylenimine, PEI: H(-NHCH2CH2)NH2,
water-soluble polymer.
poly-L-glutamate: a polypeptide of (pure) L-glutamic acid.
poly-L-glutamate probe method: a method introduced in 1967 by
Ling and Kromash336 for estimating the size of extracellular
space in frog muscle and other tissues.
polylysine: polypeptide of pure L-, D- or D,L-lysine.
polylysine-treated-collodion-coated glass electrode, PCG electrode:
a glass electrode first coated with collodion and (before it is dried)
soaked overnight in a solution of polylysine hydrochloride (3 mg/ml)
before drying in 43% humidity provided by a saturated К2СО3
solution.
polymer: a large chemical compound formed by the joining together
(polymerization) of a sequence of repeating units called monomers.
polyol, polyhydric alcohols: Unlike sugars which are polyhydroxy
aldehydehydes and ketones, polyols contain only alcohol groups. Polyols
can be divided into (i) "straight-chain" or acyclic polyols which
include ethylene glycol, glycerol, erythritol, xylitol, D-mannitol and
sorbitol; (ii) ring-structured, or alicyclic polyols which
include various inositols, e.g., myo-inositol.
polypeptide: a molecular chain of amino-acid residues joined
through peptide linkages.
polypeptide backbone, "backbone", backbone: the linked portion of
a polypeptide chain exclusive of the side chains, R, R',
R" etc. in -NHCOCHR-NHCOCHR'-NHCOCHR''-
polypeptide chain: See polypeptide.
polysaccharide: a large carbohydrate that can be decomposed by
hydrolysis into two or more molecules of monosaccharides like D-glucose
Examples include starch, cellulose, glycogen.
polystyrene sulfonate: Polystyrene, a polymer produced by joining
styrene (С6Н5СН2=СН2)
monomers into a linear chain, that carries a sulfonate group When
polystyrene sulfonate is cross-linked into a three-dimensional network,
it becomes one of the earlier form of cation exchange resin (e.g., Dowex
50).
polyvinylmethylether, PVME: (-СН2СНОСН3-)n
a water-soluble high molecular weight polymer.
polyvinylpyrrolidone, PVP: water-soluble polymer with medium
molecular weight of 25,000.
potassium ferrocyanide: K4Fe(CN)6 3Н2О,
yellow crystals soluble in water.
potassium picrate: C6Н2(NO2)3ОK,
the potassium salt of picric acid Yellow, reddish or greenish lustrous
crystals.
precipitate: a substance, which has separated from a solution or
suspension in response to chemical or environmental change, usually in
the form of insoluble amorphous or crystalline solids.
preexistence theory: A basic cell physiological theory advocated
by Emil DuBois-Reymond (1818-1896) that the cellular resting potential
(known at that time only in the form of a grossly diminished and
distorted version (aptly) called the injury potential or demarcation
potential) exists across the surface of normal resting (nerve and
muscle) cells and is not an artifact from injury as DuBois Reymond's
student, Ludimar Hermann, asserted in Hermann's alteration theory.
preincubate: to prepare a population of cells (e.g., a muscle)
for a specific experimental study, the cells are incubated with shaking
prior to the experiment for a length of time in a well-defined
environment so that "contaminants" (e.g., insulin) present in the cells
originally are removed beforehand and their possible undesirable impact
on the experimental results thus forestalled.
primary structure of proteins: describing the kind, number and
sequential order of amino-acid residues in a protein.
primer: A concept introduced by Ling, Will and Shannon in 1969480
that to bring about the full accumulation in frog muscles of D-glucose
at 0° C, prior incubation of the tissues at a higher temperature (e.g.,
25° C) and in the presence of insulin and a sugar like D-glucose, D-xylose
at a suitable concentration is essential. D-glucose, D-xylose and five
other sugars bearing structural similarity to D-glucose are called
primers because their presence are essential for the accumulation of
more molecules of similar structures. (Not to be confused with DNA
primers in the further formation of DNA production though the underlying
mechanisms may bear similarities.)
principal cardinal adsorbent: a cardinal adsorbent like ATP,
which has supreme controlling authority.
principle of enhanced association with site fixation: See theory
of association through site fixation.
proline: a common
α-amino acid found in most protein hydrolysates. Like
hydroxyproline, a proline residue in a polypeptide chain or protein
cannot form intra-, or intermacro-molecular H bonds because its peptide
nitrogen, being a part of a peptide-linked pyrrolidine ring, lacks a
(second) H atom.
n-propanol, n-propyl alcohol: СН3СН2СН2СООН.
protein: any one of a group of complex organic nitrogenous
compounds, widely distributed in plants and animals, which form the
principal constituent of cell protoplasm They are essentially linear
combinations of
α-amino acids, possessing in each a polypeptide chain.
proteinate: a compound of a protein.
proteinoid microsphere: microscopic spheres of materials
containing mostly protein-like materials (see Fig. 5E).
proton: positive ion of (gaseous) hydrogen atom or a hydrogen
atom that has lost its electron. Name given by E. Rutherford from the
Greek word, protos meaning "first".
protoplasm: all matter of which life is a manifestation; the
ubiquitous and essential material of animal and plant cells.
Protoplasmic doctrine: a principle announced by Max Schultze in
1861 that living cells are a membrane-less lump of protoplasm
surrounding a nucleus.
protoplasmic droplet: The more fluid protoplasm like the
endoplasm of internodal cells of giant alga Nitella can be
"poured out" of the cell through a cut end and collects in an aqueous
solution as one or more protoplasmic droplets (for illustration, see
Fig. 3b).
protoplast: When a mature plant cell is immersed in a hypertonic
solution of sucrose or NaCl, the cell content from the plasma membrane
inward shrinks away from the rigid enclosing cell wall. Protoplast is
the name von Hanstein gave to the shrunken body of protoplasm thus
formed.27 (See Fig. 1B.)
protozoa: the phylum of one-celled animals, usually microscopic
in size, which forms the lowest division of the animal kingdom.
proximal functional group: functional groups of a protein
molecule, which are on, or close in distance from the polypeptide chain.
proximal site: a site that is close-by (usually measured from the
starting point of the polypeptide chain of a protein).
psyche: soul or mind in early Greek philosophy.
Purkinje muscle fiber: any of the modified cardiac muscle fiber
that have few nuclei, granulated cytoplasm, sparse peripheral striation
and make up a network of conducting tissue in the myocardium.
PVME: See polyvinylmethylether.
PVP: See polyvinylpyrrolidone.
PVP 360: polyvinylpyrrolidone with an average molecular weight of
360,000.
pyrrolidine nitrogen atom: The nitrogen atom of a proline or
hydroxyproline residue in a polypeptide or protein is part of the five-membered
pyrrolidine ring structure.
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