facilitated diffusion see passive transport FADH2 (reduced flavin adenine dinucleotide) Activated carrier molecule
that is produced by the citric acid cycle. FAK see focal adhesion kinase Fas protein (Fas) Membrane-bound receptor that initiates apoptosis in the
receptor-bearing cell after binding to its ligand (Fas ligand). fat Energy-storage lipid in cells. It is composed of triglycerides fatty acids
esterified with glycerol. fat cell Connective-tissue cell that produces and stores fat in animals. fatty acid Compound such as palmitic acid that has a carboxylic acid attached
to a long hydrocarbon chain. Used as a major source of energy during
metabolism and as a starting point for the synthesis of phospholipids. Fc receptor One of a family of receptors specific for the invariant constant
region (Fc region) of immunoglobulins (other than IgM and IgD); different Fc
receptors are specific for IgG, IgA, IgE and their subclasses. feedback inhibition Type of regulation of metabolism in which an enzyme
acting early in a reaction pathway is inhibited by a late product of that pathway. fermentation Anaerobic energy-yielding metabolic pathway in which
pyruvate produced by glycolysis is converted, for example, into lactate or
ethanol, with the conversion of NADH to NAD+. fertilization Fusion of a male and a female gamete (both haploid) to form a
diploid zygote, which develops into a new individual. fibrillar collagen Type of collagen molecule which assembles into rope-like
structures. Collagens type I (common in skin), II, III, V and XI are of this type. fibroblast Common cell type found in connective tissue. Secretes an
extracellular matrix rich in collagen and other extracellular matrix
macromolecules. Migrates and proliferates readily in wounded tissue and in
tissue culture. fibronectin Extracellular matrix protein that is involved in adhesion of cells to
the matrix and the guidance of migrating cells during embryogenesis. Integrins
on the cell surface are receptors for fibronectin. filopodium (filopodia) Thin, spike-like protrusion with an actin filament core,
generated on the leading edge of a crawling animal cell. fission yeast Common name often given to the yeast Schizosaccharomyces pombe, a common experimental organism. It divides to give two equal-sized
cells. fixative Chemical reagent such as formaldehyde or osmium tetroxide used to
preserve cells for microscropy. Samples treated with these reagents are said to
be "fixed," and the process is called fixation. flagellum (flagella) Long, whiplike protrusion whose undulations drive a cell
through a fluid medium. Eucaryotic flagella are longer versions of cilia.
Bacterial flagella are smaller and completely different in construction and mechanism of action. fluid-phase endocytosis Type of endocytosis in which small vesicles bud off
internally from the plasma membrane, carrying extracellular fluid and
dissolved material into the cell. (See also pinocytosis.) fluorescein Fluorescent dye that fluoresces green when illuminated with blue
light or ultraviolet light. fluorescence microscope Microscope designed to view material stained with
fluorescent dyes. Similar to a light microscope but the illuminating light is
passed through one set of filters before the specimen, to select those
wavelengths that excite the dye, and through another set of filters before it
reaches the eye, to select only those wavelengths emitted when the dye
fluoresces. fluorescent dye Molecule that absorbs light at one wavelength and responds
by emitting light at another wavelength. The emitted light is of longer
wavelength (and hence of lower energy) than the light absorbed. fluorescent resonance energy transfer (FRET) Technique for monitoring the
closeness of two fluorescently labeled molecules (and thus their interaction) in
cells. focal adhesion kinase (FAK) Cytoplasmic tyrosine kinase present at cellmatrix
junctions (focal adhesions) in association with the cytoplasmic tails of
integrins. focal adhesion, focal contact (adhesion plaque) A type of anchoring cell
junction, forming a small region on the surface of a fibroblast or other cell that
is anchored to the extracellular matrix. Attachment is mediated by
transmembrane proteins such as integrins, which are linked, through other
proteins, to actin filaments in the cytoplasm. follicle cell One of the cell types that surround a developing oocyte or egg. free energy (G) The energy that can be extracted from a system to drive
reactions. Takes into account changes in both energy and entropy. free ribosome Ribosome that is free in the cytosol, unattached to any
membrane. It is the site of synthesis of all proteins encoded by the nuclear
genome other than those destined to enter the endoplasmic reticulum. free-energy change (DG) Change in the free energy during a reaction: the free
energy of the product molecules minus the free energy of the starting
molecules. A large negative value of DG indicates that the reaction has a strong tendency to occur. freeze-fracture electron microscopy Technique for studying membrane
structure, in which the membrane of a frozen cell is fractured along the interior
of the bilayer, separating it into the two monolayers with the interior faces
exposed. FRET see fluorescent resonance energy transfer fungus (fungi) Kingdom of eucaryotic organisms that includes the yeasts,
molds, and mushrooms. Many plant diseases and a relatively small number of
animal diseases are caused by fungi.
