Molecular Biology of the Cell by Bruce Alberts, Alexander Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter Walter by by Bruce Alberts, Alexander Johnson, Julian Lewis, David Morg

Glossary G:11
giving rise to all the cells in the body. Can be grown in culture,
genetically modified, and inserted into a blastocyst to develop a
transgenic animal.
endocrine cell Specialized animal cell that secretes a
hormone into the blood. Usually part of a gland, such as the
thyroid or pituitary gland.
endocytic vesicle Vesicle formed as material ingested by
the cell during endocytosis is progressively enclosed by a small
portion of the plasma membrane, which first invaginates and
then pinches off to form the vesicle.
endocytosis Uptake of material into a cell by an invagination
of the plasma membrane and its internalization in a membraneenclosed
vesicle. See also pinocytosis and phagocytosis.
endoderm Embryonic tissue that is the precursor of the gut
and associated organs.
endoplasmic reticulum (ER) Labyrinthine membranebounded
compartment in the cytoplasm of eukaryotic cells,
where lipids are synthesized and membrane-bound proteins
and secretory proteins are made. (Figure 12–33)
endosome maturation Process by which early endosomes
mature to late endosomes and endolysosomes; in the
conversion process, the endosome membrane protein
composition changes, the endosome moves from the cell
periphery to close to the nucleus, and the endosome ceases
to recycle material to the plasma membrane and irreversibly
commits its remaining contents to degradation.
endothelial cell Flattened cell type that forms a sheet (the
endothelium) lining all blood and lymphatic vessels.
entropy (S) Thermodynamic quantity that measures the
degree of disorder or randomness in a system; the higher the
entropy, the greater the disorder. (Panel 2–7, pp. 102–103)
enveloped virus Virus with a capsid surrounded by a lipid
bilayer membrane (the envelope), which is often derived from
the host-cell plasma membrane when the virus buds from the
cell. (Figure 23–12)
enzyme Protein that catalyzes a specific chemical reaction.
enzyme-coupled receptor A major type of cell-surface
receptor that has a cytoplasmic domain that either has
enzymatic activity or is associated with an intracellular enzyme.
In either case, the enzymatic activity is stimulated by an
extracellular ligand binding to the receptor. (Figure 15–6)
ephrin One of a family of membrane-bound protein ligands
for the Eph receptor tyrosine kinases (RTKs) that, among many
other functions, stimulate repulsion or attraction responses that
guide the migration of cells and nerve cell axons during animal
development.
epidermis Epithelial layer covering the outer surface of the
body. Has different structures in different animal groups. The
outer layer of plant tissue is also called the epidermis.
epigenetic inheritance Inheritance of phenotypic changes
in a cell or organism that do not result from changes in the
nucleotide sequence of DNA. Can be due to positive feedback
loops of transcription regulators or to heritable modifications in
chromatin such as DNA methylation or histone modifications.
(Figure 7–53)
epistasis analysis Analysis to discover the order in which the
genes act, by investigating if a mutation in one gene can mask
the effect of a mutation in another gene when both mutations
are present in the same organism or cell.
epithelial tissues Tissues, such as the lining of the gut or the
epidermal covering of the skin, in which cells are closely bound
together into sheets called epithelia.
epithelium (plural epithelia) Sheet of cells covering the outer
surface of a structure or lining a cavity.
equilibrium State in a chemical reaction where there is no net
change in free energy to drive the reaction in either direction.
The ratio of product to substrate reaches a constant value at
chemical equilibrium. (Figure 2–30)
equilibrium constant (K) The ratio of forward and reverse
rate constants for a reaction. Equal to the association or affinity
constant (K a ) for a simple binding reaction (A + B AB). See
also affinity constant, dissociation constant. (See page 62)
ER lumen Space enclosed by the membrane of the
endoplasmic reticulum (ER).
ER resident protein Protein that remains in the endoplasmic
reticulum (ER) or its membranes and carries out its function
there, as opposed to proteins that are present in the ER only in
transit.
ER retention signal Short amino acid sequence on a protein
that prevents it from moving out of the endoplasmic reticulum
(ER). Found on proteins that are resident in the ER and function
there.
ER signal sequence N-terminal signal sequence that directs
proteins to enter the endoplasmic reticulum (ER). Cleaved off by
signal peptidase after entry.
ER tail-anchored proteins Membrane proteins anchored
in the endoplasmic reticulum (ER) membrane by a single
transmembrane α helix contained at their C-terminus.
erythrocyte Small hemoglobin-containing blood cell of
vertebrates that transports oxygen to, and carbon dioxide from,
tissues. Also called a red blood cell.
erythropoietin A hormone produced by the kidney that
stimulates the production of red blood cells in bone marrow.
ESCRT protein complexes Four protein complexes
(ESCRT-0, ESCRT-1, ESCRT-2, and ESCRT-3) that act
sequentially to shepherd mono-ubiquitylated membrane
proteins on endosomal membranes into intralumenal vesicles.
ESCRT-3 complex catalyzes the pinching-off reaction.
ethylene Small gas molecule that is a plant growth regulator
influencing plant development in various ways including
promoting fruit ripening, leaf abscission, and plant senescence
and functioning as a stress signal in response to wounding,
infection, and flooding.
euchromatin Region of an interphase chromosome that
stains diffusely; “normal” chromatin, as opposed to the more
condensed heterochromatin.
eukaryote Organism composed of one or more cells that
have a distinct nucleus. Member of one of the three main
divisions of the living world, the other two being bacteria and
archaea. (Figure 1–17)
eukaryotic initiation factor (eIF) Protein that helps load
initiator tRNA on to the ribosome, thus initiating translation.
excitatory neurotransmitter Neurotransmitter that opens
cation channels in the postsynaptic membrane, causing an
influx of Na + , and in many cases Ca 2+ , that depolarizes the
postsynaptic membrane toward the threshold potential for firing
an action potential.
executioner caspases Apoptotic caspases that catalyze the
widespread cleavage events during apoptosis that kill the cell.