Biotechnology

Selective Estrogen Receptor Modulators
Abbreviated SERM. This term refers to
chemical compounds (isoflavones, the phar-
maceuticals Evista/raloxifene and tamox-
ifen, etc.) which impart some beneficial
effect on the human body when consumed
by humans, without any of the adverse
impacts of estrogen (e.g., promotion of the
growth of certain tumors by estrogen). See
also
SELECTIVE ESTROGEN EFFECT
,
ESTROGEN
,
ISOFLAVONES
,
PHYTOCHEMICALS
.
Self-Assembly (of a large molecular struc-
ture) The essentially automatic ordering and
assembly of certain molecules into a large
structure. Examples of such large molecular
structures (often called supramolecular
© 2002 by CRC Press LLC

S
structures or supramolecular assemblies)
include micelles, reverse micelles, ribosomes,
peptide nanotubes, and Tobacco Mosaic
Virus (TMV).
The first discovery of a self-assembling
active biological structure occurred in 1955,
when Heinz Frankel-Conrat and Robley Wil-
liams showed that TMV will reassemble into
functioning, infectious virus particles (after
TMV has been dissociated into its compo-
nents via immersion in concentrated acetic
acid). In the future, it is hoped that man will
be able to “direct” the self-assembly of
molecular structures which will:
• Serve as “cages” to carefully protect and
deliver sensitive/unstable pharmaceuti-
cals to targeted tissues within the body.
• Serve as “crucibles” (i.e., reaction ves-
sels) for small-scale chemical reactions
to occur within.
• Serve as computer logic or memory
devices (i.e., bioelectronics).
• Serve as antibiotics.
For example, during the 1990s, M. Reza
Ghadiri created “peptide nanotubes” made
via self-assembly of certain peptides into
tubes (cylinders) of nanometer dimensions.
These peptide nanotubes are “membrane
active” (i.e., insert one end of themselves
into the outer membrane of a cell), and cause
the cell (e.g., pathogenic bacteria) contents to
“leak out,” which kills the bacteria. See also
MICELLE
,
REVERSE MICELLE
  (
RM
),
RIBOSOMES
,
TOBACCO MOSAIC VIRUS
  (
TMV
),
NANOCRYSTAL
MOLECULES
,
NANOSCIENCE
,
NANOTECHNOLOGY
,
NANOMETERS
 (
NM
),
BIOELECTRONICS
,
ANTIBIOTIC
,
PATHOGEN
,
BACTERIA
.
Semisynthetic Catalytic Antibody An anti-
body produced (e.g., via monoclonal anti-
body techniques) in response to a carefully
selected antigen (i.e., one of the molecules
involved in the chemical reaction that you
are trying to catalyze). Such an antibody is
then made to be catalytic by “attaching” a
(molecular) group that is known to catalyze
the desired chemical reaction. This attaching
is done either via chemical modification of
the antibody, or via genetic engineering of
the cell (DNA) that produces that antibody.
See also 
CATALYST
,
ANTIBODY
,
CATALYTIC
ANTIBODY
,
SITE
-
DIRECTED MUTAGENESIS
  (
SDM
),
MONOCLONAL ANTIBODIES
  (
MA
b
),
ANTIGEN
,
GENETIC ENGINEERING
,
ABZYMES
.
Senior Advisory Group on Biotechnology
(SAGB) An association of approximately
35 of the largest European companies that
are engaged in at least some form of genetic
engineering research or production. Similar
to America’s Biotechnology Industry Orga-
nization (BIO), the SAGB works with gov-
ernments and the public to promote safe and
rational advancement of genetic engineering
and biotechnology. It was formed in 1989
and is based in Brussels, Belgium. See also
BIOTECHNOLOGY
,
GENETIC ENGINEERING
,
RECOM-
BINANT DNA
 (
r
DNA
),
JAPAN BIO
-
INDUSTRY ASSO-
CIATION
,
INTERNATIONAL FOOD BIOTECHNOLOGY
COUNCIL
  (
IFBC
),
BIOTECHNOLOGY INDUSTRY
ORGANIZATION
 (
BIO
).
Sense Normal (forward) orientation of DNA
sequence (gene) in genome. See also 
GENE
SILENCING
,
ANTISENSE
 (
DNA SEQUENCE
).
Sepsis Also known as systemic inflammatory
response syndrome, this life-threatening
condition (“septic shock”) occurs when the
body’s immune system over-responds to
infection (e.g., by gram-negative bacteria) in
which release of bacterial endotoxin
(lipopolysaccharide, or LPS) occurs. Those
immune system cells (e.g., macrophages,
etc.) overproduce numerous inflammatory
agents (e.g., cytokines), which induce fever,
shock, and sometimes organ failure. See also
GRAM
-
NEGATIVE
  (
G
-),
BACTERIA
,
CYTOKINES
,
ENDOTOXIN
,
MACROPHAGE
.
Septic Shock See
SEPSIS
.
Sequence (of a DNA molecule) The specific
nucleic acids that comprise a given segment
of a DNA molecule. See also 
DEOXYRIBO-
NUCLEIC ACID
  (
DNA
),
GENETIC CODE
,
GENE
,
CHROMOSOMES
,
NUCLEIC ACIDS
,
CONTROL
SEQUENCES
,
SEQUENCING
  (
OF DNA MOLECULES
),
STRUCTURAL GENOMICS
,
COMPLEMENTARY
(
MOLECULAR GENETICS
).
Sequence (of a protein molecule) The specific
amino acids (and the order in which they are
coupled together) that comprise a given seg-
ment of a protein molecule. See also 
PROTEIN
,
AMINO ACID
,
STRUCTURAL GENE
,
GENOMICS
,
© 2002 by CRC Press LLC

S
STRUCTURAL GENOMICS
,
SEQUENCING
 (
OF PROTEIN
MOLECULES
).
Sequence Map A pictorial representation of
the sequence of amino acids in a protein
molecule, the sequence of nucleic acids in a
DNA molecule, or the sequence of oligosac-
charide components in a glycoprotein/carbo-
hydrate molecule. See also 
SEQUENCING
  (
OF
DNA MOLECULES
),
SEQUENCING
 (
OF PROTEIN MOL-
ECULES
),
SEQUENCING
  (
OF OLIGOSACCHARIDES
),
SEQUENCE
 (
OF A DNA MOLECULE
),
SEQUENCE
 (
OF
A PROTEIN MOLECULE
),
RESTRICTION MAP
.
Sequencing (of DNA molecules) The process
used to obtain the sequential arrangement of
nucleotides in the DNA backbone. The
cleavage into fragments (followed by sepa-
ration of those fragments, which can then be
sequenced individually) of DNA molecules
by one of several methods: (1) a chemical
cleavage method followed by polyacryla-
mide gel electrophoresis (PAGE) or capillary
electrophoresis, (2) a method consisting of
controlled interruption of enzymatic replica-
tion methods followed by PAGE, (3) a
didexyl method utilizing fluorescent “tag”
atoms attached to the DNA fragments, fol-
lowed by use of spectrophotometry to iden-
tify the respective DNA fragments by their
differing “tags” (which fluoresce at different
wavelengths). This (fluorescent tag) variant
of the dideoxy method can be automated to
“decipher” large DNA molecules (i.e.,
genomes). Such automated machines are
sometimes called “gene machines.”
Sequencing of DNA was first done in the
mid-1970s by Frederick Sanger. See also
POLYACRYLAMIDE GEL ELECTROPHORESIS
 (
PAGE
),
GENE MACHINE
,
DEOXYRIBONUCLEIC ACID
 (
DNA
),
SEQUENCE
 (
OF A DNA MOLECULE
),
BASE EXCISION
SEQUENCE SCANNING
 (
BESS
),
SHOTGUN SEQUENC-
ING
,
NANOPORE
,
NEAR
-
INFRARED SPECTROSCOPY
(
NIR
),
COMPARATIVE SEQUENCING
,
BIOCHIPS
.
Sequencing (of oligosaccharides) See
RESTRIC-
TION ENDOGLYCOSIDASES
,
SEQUENCE MAP
.
Sequencing (of protein molecules) The pro-
cess used to obtain the sequential arrange-
ment of amino acids in a protein molecule.
See also 
PROTEIN
,
AMINO ACID
,
SEQUENCE
  (
OF
A PROTEIN MOLECULE
).
Sequon A (potential) site on a protein mole-
cule’s “backbone” where a sugar molecule
(or a chain of sugar molecules, i.e., an oligo-
saccharide) may be attached. See also 
PROTEIN
,
SUGAR MOLECULES
,
GLYCOPROTEIN
,
GLYCOGEN
,
G L Y C O S Y L A T I O N
,
P R O T E I N
E N G I N E E R I N G
,
OLIGOSACCHARIDES
.
Serine (ser) A nonessential amino acid; a bio-
synthetic precursor of several metabolites,
including cysteine, glycine, and choline. In
1999, Solomon H. Snyder, Herman
Wolosker, and Seth Blackshaw conducted
research that showed that some mammals
synthesize (manufacture) 
D
-serine within
their brains, and it functions as a neurotrans-
mitter there. See also 
ESSENTIAL AMINO ACIDS
,
METABOLITE
,
CYSTEINE
  (
cys
),
GLYCINE
  (
G
ly
),
CHOLINE
,
NEUROTRANSMITTER
.
Seroconversion The development of antibod-
ies (specific to that disease-causing microor-
ganism) in response to vaccination or natural
exposure to a disease-causing microorgan-
ism. See also 
SEROLOGY
,
ANTIBODY
,
IMMUNO-
GLOBULIN
,
HUMORAL IMMUNITY
,
PATHOGEN
,
POLYCLONAL ANTIBODIES
,
PASSIVE IMMUNITY
.
Serologist See
SEROLOGY
.
Serology A subdiscipline of immunology, con-
cerned with the properties and reactions of
blood sera. It includes the diverse techniques
used for the “test tube” measurement of anti-
body-antigen reactions, including blood typ-
ing (e.g., for transfusions). See also 
MAJOR
HISTOCOMPATIBILITY COMPLEX
  (
MHC
),
OLIGO-
SACCHARIDES
,
SERUM LIFETIME
.
Seronegative Refers to negative results of a
serology test. See also 
SEROLOGY
,
HUMORAL
IMMUNITY
,
ANTIBODY
.
Serotonin An important neurochemical whose
effects upon the human brain include mood
elevation. Production of serotonin in the
brain is increased by ingestion of the amino
acid tryptophan (a chemical precursor to
serotonin). Elevation of brain levels of sero-
tonin can also be caused by consumption of
the herb known as Saint John’s Wort
(Hypericum perforatum), or by consumption
of certain pharmaceuticals such as the anti-
depressants Prozac™ (trademarked product
of Eli Lilly & Company), Zoloft™ (trade-
marked product of Pfizer, Inc.), or Paxil™
(trademarked product of Smithkline Beecham
PLC). In 1997, Marianne Regard and
Theodor Landis discovered that humans
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afflicted with hemorrhagic lesions in the
brain (cause of abnormal serotonin activa-
tion/production) often became “passionate
culinary afficionados.” See also 
TRYPTOPHAN
(
trp
),
ESSENTIAL AMINO ACIDS
,
BLOOD
-
BRAIN
BARRIER
 (
BBB
),
NEUROTRANSMITTER
.
Serotypes A variety (sub-strain) of a microor-
ganism that is distinguished from others (in
the strain) via its serological effects (within
immune system of the host organism it
inhabits). See also 
BACTERIA
,
STRAIN
,
E
.
COLI
0157
:
H
7
,
SEROLOGY
,
HUMAN IMMUNODEFICIENCY
VIRUS TYPE
1
 (
HIV-
1
),
HUMAN IMMUNODEFICIENCY
VIRUS TYPE
2
 (
HIV-
2
).
Serum Blood plasma that has had its clotting
factor removed. See also 
FACTOR VIII
,
FACTOR
IX
,
PLASMA
.
Serum Half Life See
SERUM LIFETIME
.
Serum Immune Response See
HUMORAL IMMU-
NITY
.
Serum Lifetime The average length of time
that a molecule circulates in an organism’s
bloodstream before it is cleared from the
bloodstream. See also 
IMMUNE RESPONSE
,
ANTIGEN
.
Sessile (Micro)organisms that are attached to
a (support) substrate directly by their base;
not attached via an intervening peduncle
(i.e., stalk). Can also refer to fruit or leaves
that are attached directly to the main stem
or branch of a plant. See also 
VAGILE
.
Sex Chromosomes T h o s e   c h r o m o s o m e s
whose content is different in the two sexes
of a given species. They are usually labeled
X and Y (or W and Z); one sex has XX (or
WW), the other sex has XY (or WZ). XX
(WW) is female and XY (WZ) is male.
Sexual Conjugation An infrequent occurrence
in which two adjacent bacteria stretch out por-
tions of their (cell) membranes to touch one
another, fuse, and then pass transposons,
jumping genes, or plasmids to each other. See
also
ASEXUAL
,
BACTERIA
,
CELL
,
CONJUGATION
,
PLASMID
,
TRANSPOSON
,
JUMPING GENES
.
Shotgun Cloning Method A technique for
obtaining the desired gene that involves
“chopping up” the entire genetic complement
of a cell using restriction enzymes, then
attaching each (resultant) DNA fragment to a
vector and transferring it into a bacterium, and
finally screening those (engineered) bacteria
to locate the bacteria that are producing the
desired product (e.g., a protein). See also
GENETIC ENGINEERING
,
GENOME
,
RESTRICTION
ENDONUCLEASES
,
VECTOR
.
Shotgun Sequencing Sometimes called Whole-
genome Shotgun Sequencing. A technology
for rapid sequencing of DNA, in which an
organism’s genome (DNA) is first frag-
mented (“broken up”), and then randomly
selected pieces of the DNA are individually
sequenced. Those individual pieces’
sequences must subsequently be “bridged”
(i.e., “assembled” in an overlapping end-by-
end pattern) in order to assemble a complete
map (e.g., of an organism’s chromosome or
genome). See also 
SEQUENCING
 (
OF DNA MOL-
ECULES
),
DEOXYRIBONUCLEIC ACID
  (
DNA
),
SEQUENCE
 (
OF A DNA MOLECULE
),
GENOME
,
DNA
“
BRIDGES
”,
CHROMOSOME
,
GENETIC MAP
.
Shuttle Vector A vector capable of replicating
in two unrelated species. See also 
VECTOR
,
REPLICATION
 (
OF VIRUS
).
Signal Transducers and Activators of Tran-
scription (STATs) Molecules that cause
signal transduction to occur (i.e., when a
hormone or other chemical “binds” to it), or
molecules that cause transcription to occur
(i.e., when transcription factor(s) “bind” to
it). STATs can be attached to solid surfaces
(e.g., in a bioassay or biosensor) for use in
such research applications as high-through-
put screening. See also 
SIGNAL TRANSDUCTION
,
HORMONE
,
TRANSCRIPTION FACTORS
,
BIOCHIPS
,
BIOSENSORS
  (
ELECTRONIC
),
BIOASSAY
,
HIGH
-
THROUGHPUT SCREENING
  (
HTS
),
MICROARRAY
(
TESTING
),
TARGET
 (
OF A HERBICIDE OR INSECTI-
CIDE
),
CASCADE
.
Signal Transduction The “reception” and
“conversion” of a “chemical message” (e.g.,
hormone) by a cell. For example, G-proteins
(which are embedded in the surface mem-
brane of certain cells, but extend through to
outside and inside of the membrane) accom-
plish signal transduction. When a hormone,
drug, neurotransmitter, or other signal chem-
ical binds (i.e., “docks”) to the receptor (on
the exterior of the cell’s plasma membrane),
the receptor activates the G-protein, causing
an effector inside cell to produce a “signal”
© 2002 by CRC Press LLC

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chemical inside the cell, which then reacts
to the original external chemical signal
received. See also 
CELL
,
PLASMA MEMBRANE
,
TRANSMEMBRANE PROTEINS
,
RECEPTORS
,
EGF
RECEPTOR
,
RAS GENE
,
NUCLEAR RECEPTORS
,
SIG-
NALING
,
G
-
PROTEINS
,
MAST CELLS
,
CD
95
PROTEIN
,
HORMONE
,
SUBSTANCE P
,
LECITHIN
,
CASCADE
.
Signaling The “communication” that occurs
between and within cells of an organism, e.g.,
via hormones, nitric acid, etc. Such signaling
“tells” certain cells to grow, change, or pro-
duce specific proteins at specific times. See
also
RECEPTORS
,
PROTEIN
,
NUCLEAR RECEPTORS
,
G
-
PROTEINS
,
SIGNAL TRANSDUCTION
  (
SIGNAL
),
TRANSDUCTION
 (
GENE
),
CD
95
PROTEIN
,
HORMONE
,
PARKINSON
’
S DISEASE
,
HARPIN
,
SUBSTANCE P
,
LECITHIN
,
NITRIC OXIDE
,
SIGNAL TRANSDUCERS
AND ACTIVATORS OF TRANSCRIPTION
  (
STAT
s
),
PROTEIN SIGNALING
,
CASCADE
,
CHOLINE
.
Signaling Molecule A molecule utilized to
“signal” (communicate) with cells, or to
deliver a signal to other organisms (e.g., a
signal by the soybean plant to attract bene-
ficial Rhizobium bacteria to colonize the
roots of that soybean plant).
For example, the young offspring of fleas
can remain immature (larvae) for up to 2 years
in the absence of a food source, until carbon
dioxide molecules and heat from a nearby
mammal (potential host/food source) signal
them to mature into adults in order to prey on
the mammal. Another example: the larvae of
North American tree frogs are signaled by
chemicals released into a pond’s water when
the first such frog larva is killed by a (preda-
tory) dragonfly nymph (i.e., when those drag-
onflies first arrive each year at a given pond,
to prey on the frog larvae). That chemical
“signal” causes all of the North American tree
frog larvae in that pond to subsequently grow
tails that are twice as large as were grown by
them prior to that chemical signal, to facilitate
their escape from the dragonfly nymphs. See
also
SIGNALING
,
NITRIC OXIDE
,
G-PROTEINS
,
HOR-
MONE
,
SUBSTANCE P
,
LEUKOTRIENES
,
ISOFLA-
VONES
,
SOYBEAN PLANT
,
RHIZOBIUM
  (
BACTERIA
),
HARPIN
,
OCTADECANOID
/
JASMONATE SIGNAL COM-
PLEX
,
SALICYCLIC ACID
 (
SA
).
Signaling Protein See
SIGNALING MOLECULE
.
Silencing See
GENE SILENCING
.
Silent Mutation A mutation in a gene that
causes no detectable change in the biological
characteristics of that gene’s product (e.g., a
protein). See also 
EXPRESS
,
GENE
,
PROTEIN
.
Silk A natural, protein polymer with a predom-
inance of alanine and glycine amino acids.
Silk is produced by silkworms that have fed
on mulberry tree leaves. The body of a silk-
worm can retain proteins (i.e., raw material
for silk) amounting to as much as 20% of its
body weight. It is thought that silk may be
altered, via genetic engineering of silk-
worms, to produce fibers of very high
strength. See also 
GENETIC ENGINEERING
,
PRO-
TEIN ENGINEERING
,
AMINO ACID
.
Simple Protein A protein that yields only
amino acids on hydrolysis (i.e., cleavage of
the protein molecule into fragments), and
does not have other molecular constituents
such as lipids or polysaccharide attachments.
See also 
PROTEIN
,
AMINO ACID
,
GLYCOPROTEIN
,
LIPIDS
,
POLYSACCHARIDES
.
Simple Sequence Repeat (SSR) DNA Marker
Technique A “genetic mapping” technique
which utilizes the fact that microsatellite
sequences “repeat” (appear repeatedly in
sequence within the DNA molecule) in a
manner enabling them to be used as “mark-
ers.” See also 
GENETIC MAP
,
SEQUENCE
  (
OF A
DNA MOLECULE
),
RANDOM AMPLIFIED POLYMOR-
PHIC DNA
 (
RAPD
)
TECHNIQUE
,
RESTRICTION FRAG-
MENT LENGTH POLYMORPHISM
 (
RFLP
)
TECHNIQUE
,
DEOXYRIBONUCLEIC ACID
  (
DNA
),
PHYSICAL MAP
(
OF GENOME
),
LINKAGE
,
LINKAGE GROUP
,
MARKER
(
GENETIC MARKER
),
LINKAGE MAP
,
TRAIT
,
MICRO-
SATELLITE DNA
,
QUANTITATIVE TRAIT LOCI
 (
QTL
).
Single-Cell Protein (SCP) Protein derived
from single-celled organisms with a high
protein content. Yeast is an example. Gener-
ally used in regard to those organisms that
are edible by domesticated animals or
humans. Single-Domain Antibodies (dAbs)
VH “heavy chains” (portion of antibody
molecules) produced by genetically engi-
neered Escherichia coli cells that act to bind
antigens in a manner similar to antibodies or
monoclonal antibodies (MAbs). Similar to
MAbs, dAbs can be produced in large quan-
tities, to be used as human or animal thera-
peutics (e.g., to combat diseases). See also
© 2002 by CRC Press LLC

S
ANTIBODY
,
MONOCLONAL ANTIBODIES
  (
MA
b
),
ANTIGEN
,
ESCHERICHIA COLI
.
Single-nucleotide Polymorphisms (SNPs)
Variations (in individual nucleotides) that
occur within DNA at the rate of approxi-
mately one in every 1,300 base pairs in most
organisms (approximately one in every 100
base pairs in humans’ DNA). SNPs usually
occur in the same genomic location (e.g., on
the organism’s DNA) in different individu-
als. These variations account for:
• Diversity within a given species (e.g.,
black cattle and white cattle, different
strains/serotypes within a given bacte-
ria species, etc.)
• Some genetic diseases [e.g., the disease
cystic fibrosis is due to one SNP, the
disease known as familial dysautono-
mia is due to one SNP, the disease
known as (Duchenne) muscular dystro-
phy is due to one SNP, etc.]
• The body’s response to certain pharma-
ceuticals and food ingredients (e.g., the
diuretic drug thiazide works to control
hypertension in 60% of U.S. African
Americans, but only 8% of U.S. Cau-
casian people, due to one SNP)
Certain pharmaceuticals do not have the
desired effect in some groups of humans
possessing certain specific “grouped SNPs”
known as haplotypes. Because those “group-
ings of SNPs” are linked (i.e., tend to “travel
together” as a group within the genetics of
a given population), they can collectively
confer a given “multiple-SNP-trait” to an
identifiable subpopulation of individuals.
For example, the pharmaceuticals acetami-
nophen, aspirin, and Valium remain in the
bodies of women (who constitute a haplo-
type for that pharmacogenomic trait) longer
than in men.
Methods utilized to identify SNPs include
examination of the DNA of populations of
individuals with and without a given (genet-
ically related) disease and with and without
a given trait. “SNP mapping” is a “genetic
mapping” technique that utilizes the fact that
individual nucleotides (within a DNA mole-
cule) can exist in different forms (for a
particular “site”/location on that DNA mol-
ecule), which enables such SNPs to be uti-
lized as “markers.” One example would be
to track a given SNP vs. occurrence of genet-
ically related disease in a given human pop-
u l a t i o n .   S e e   a l s o  
P O I N T
M U T A T I O N
,
DEOXYRIBONUCLEIC ACID
  (
DNA
),
SEQUENCE
  (
OF
A DNA MOLECULE
),
NUCLEOTIDE
,
POLYMORPHISM
(
GENETIC
),
GENETICS
,
GENETIC MAP
,
PHYSICAL
MAP
  (
OF GENOME
),
GENOME
,
TRAIT
,
MARKER
(
GENETIC MARKER
),
QUANTITATIVE TRAIT LOCI
(
QTL
),
DIVERSITY
 (
WITHIN A SPECIES
),
BASE PAIR
(
bp
),
TRANSVERSION
,
CYSTIC FIBROSIS TRANS-
MEMBRANE REGULATOR PROTEIN
 (
CFTR
),
MUSCU-
LAR DYSTROPHY
  (
MD
),
PHARMACOGENETICS
,
PHARMACOGENOMICS
,
HAPLOTYPE
,
SNP MAP
,
TOXICOGENETICS
,
ORGANISM
.