facilitated diffusion
Mediated transport in
which a permease makes possible diffusion
of a molecule across a cell membrane in the
direction of a concentration gradient;
contrast with active transport.
FAD
Abbreviation for flavine adenine
dinucleotide, an electron acceptor in the
respiratory chain.
fascicle
(L. fasciculus, small
bundle). A small bundle, usually referring to
a collection of muscle fibers or nerve axons.
fatty acid
Any of a series of saturated organic
acids having the general formula CnH2nO2,
occurs in natural fats of animals and plants.
fermentation
(L. fermentum, ferment).
Enzymatic transformation, without oxygen,
or organic substrates, especially
carbohydrates, yielding products such as
alcohols, acids, and carbon dioxide.
fiber
(L. fibra, thread). A fiberlike cell or
strand of protoplasmic material produced or
secreted by a cell and lying outside the cell.
fibril
(L. fibra, thread). A strand of protoplasm
produced by a cell and lying within the cell.
fibrillar
(L. fibrilla, small fiber).
Composed of or pertaining to fibrils or fibers.
fibrin
Protein that forms a meshwork, trapping
erythrocytes, to become blood clot.
Precursor is fibrinogen.
fibrosis
Deposition of fibrous
connective tissue in a localized site, during
process of tissue repair or to wall off a
source of antigen.
filipodium
(L. filum, thread, + Gr. pous, podos, a foot). A type of
pseudopodium that is very slender and may
branch but does not rejoin to form a mesh.
filter feeding
Any feeding process by which
particulate food is filtered from water in
which it is suspended.
fission
(L. fissio, a splitting). Asexual
reproduction by a division of the body into
two or more parts.
fitness
Degree of adjustment and suitability for
a particular environment. Genetic fitness is
relative contribution to one genetically
distinct organism to the next generation;
organisms with high genetic fitness are
naturally selected and become prevalent in
a population.
flagellum
pl. flagella (L. a whip).
Whiplike organelle of locomotion.
flame cell
Specialized hollow excretory or
osmoregulatory structure of one or several
small cells containing a tuft of flagella (the
“flame”) and situated at the end of a minute
tubule; connected tubules ultimately open
to the outside. See solenocyte,
protonephridium.
fluke
(O.E. floc, flatfish). A member of class
Trematoda or class Monogenea. Also, certain
of the flatfishes (order Pleuronectiformes).
FMN
Abbreviation for flavin mononucleotide,
the prosthetic group of a protein
(flavoprotein) and a carrier in the electron
transport chain in respiration.
food vacuole
A digestive organelle in the cell.
foraminiferan
(L. foramin, hole, performation, + fero, to
bear). A member of the class
Granuloreticulosea (phylum
Sarcomastigophora) bearing a test with
many openings.
fossil
Any remains or impression
of an organism from a past geological age
that has been preserved by natural
processes, usually by mineralization in the
earth’s crust.
fossorial
Characterized by digging or burrowing.
fouling
Contamination of feeding or
respiratory areas of an organism by
excrement, sediment, or other matter. Also,
accumulation of sessile marine organisms on
the hull of a boat or ship so as to impede
its progress through the water.
founder
event Establishment of a new
population by a small number of individuals
(sometimes a single female carrying fertile
eggs) that disperse from their parental
population to a new location geographically
isolated from the parental population.
fovea
(L. small pit). A small pit or
depression; especially the fovea centralis, a
small rodless pit in the retina of some
vertebrates, a point of acute vision.
free energy
The energy available for doing
work in a chemical system.
frontal plane
A plane parallel to the main axis
of the body and at right angles to the
sagittal plane.
fusiform
(L. fusus, spindle, + forma, shape). Spindle shaped; tapering
toward each end.
|
