cellular component
component of a cell
pronucleus
The nucleus of either the ovum or the spermatozoon following fertilization. Thus, in the fertilized ovum, there are two pronuclei, one originating from the ovum, the other from the spermatozoon that brought about fertilization; they approach each oth
bacterial-type flagellum
motor complex composed of an extracellular helical protein filament coupled to a rotary motor embedded in the cell envelope
food vacuole
Vacuole within a parasite used for digestion of the host cell cytoplasm. An example of this component is found in the Apicomplexa.
slime layer
slime layer is an easily removed, diffuse, unorganized layer of extracellular material that surrounds a cell. Specifically this consists mostly of exopolysaccharides, glycoproteins, and glycolipids
specific granule
granule with a membranous, tubular internal structure, found primarily in mature neutrophil cells (most are released into the extracellular fluid); specific granules contain lactoferrin, lysozyme, vitamin B12 binding protein and elastase
yolk
material, consisting of a mixture of lipids and proteins, secreted in the form of granules, that in eggs act as a source of food for the growth and development of an embryo
glycine cleavage complex
protein complex that catalyzes the reversible oxidation of glycine. In E. coli, it has four components: dihydrolipoamide dehydrogenase, glycine dehydrogenase (decarboxylating), lipoyl-GcvH-protein and aminomethyltransferase
[Ni-Fe] hydrogenase complex
microbial enzyme complex which contains nickel and iron in its active site. In Acetomicrobium flavidum it is an alpha 2 beta 2 tetramer
platelet-derived growth factor complex
protein complex consisting of two chains of platelet-derived growth factor (PDGF) subunits
plasma membrane light-harvesting complex
plasma membrane protein-pigment complex that may be closely or peripherally associated to photosynthetic reaction centers that participate in harvesting and transferring radiant energy to the reaction center. Examples of this complex are found in b
eyespot apparatus
Small pigmented organelle used in single-celled organisms to detect light
Golgi apparatus
cell organelle that packages proteins for export
centriole
cellular organelle, found close to the nucleus in many eukaryotic cells, consisting of a small cylinder with microtubular walls
synapse
junction between a nerve fiber of one neuron and another neuron, muscle fiber or glial cell
actin filament
filament in the cytoplasm of eukaryotic cells
viral capsid
protein coat that surrounds the infective nucleic acid in some virus particles
contractile vacuole
specialized vacuole of eukaryotic cells, especially Protozoa, that fills with water from the cytoplasm and then discharges this externally by the opening of contractile vacuole pores. Its function is probably osmoregulatory
dendritic spine
small, membranous protrusion from a dendrite that forms a postsynaptic compartment
ectoplasm
part of a cell's cytoplasm
tunneling nanotube
group of membrane proteins facilitating the intercellular transport of various cellular components
cell plate
nascent cell membrane and cell wall structure that forms between two daughter nuclei near the center of a dividing plant cell
cleavage furrow
The cleavage furrow is a plasma membrane invagination at the cell division site. The cleavage furrow begins as a shallow groove and eventually deepens to divide the cytoplasm.
ribbon synapse
Type of synapse characterized by an electron-dense ribbon, lamella (bar) or spherical body in the presynaptic process cytoplasm.
TRAPP complex
large complex that acts as a tethering factor involved in transporting vesicles from the ER through the Golgi to the plasma membrane. A TRAPP (transport protein particle) complex has a core set of proteins which are joined by specific subunits depe
micronucleus
type of nucleus in ciliates, involved in reproductive cell functions
nuclear body
extra-nucleolar nuclear domains, usually visualized by confocal microscopy and fluorescent antibodies to specific proteins
astral microtubule
Any of the spindle microtubules that radiate in all directions from the spindle poles and are thought to contribute to the forces that separate the poles and position them in relation to the rest of the cell.
calcium channel complex
ion channel complex through which calcium ions pass
SAM complex
Protein complex in the outer mitochondrial membrane
efflux pump complex
protein complex that is capable of efflux transmembrane transporter activity
mitochondria associated membranes
cellular structure
complex plastid
plastid with two or more membranes
vacuole
closed structure in eukaryotic cells, completely surrounded by unit membrane and contains liquid material; cells may contain one or more vacuoles, possibly with different functions
cell wall
rigid or semi-rigid envelope lying outside the cell membrane of plant, fungal, most prokaryotic cells and some protozoan parasites, maintaining their shape and protecting them from osmotic lysi
microtubule
hollow tubes of internal diameter 12-15 nm and external diameter 24 nm found in a wide variety of eukaryotic cells
extracellular matrix
structure external to cells, which provides structural support for cells or tissues
myofibril
The contractile element of skeletal and cardiac muscle; a long, highly organized bundle of actin, myosin, and other proteins that contracts by a sliding filament mechanism.
amyloplast
part of a plant
heterochromatin
a compact and highly condensed form of chromatin
euchromatin
dispersed form of chromatin
extracellular space
part of a multicellular organism outside the cells proper, usually taken to be outside the plasma membranes, and occupied by fluid
sarcolemma
the outer membrane of a muscle cell, consisting of the plasma membrane, a covering basement membrane (about 100 nm thick and sometimes common to more than one fiber), and the associated loose network of collagen fibers
granum
Distinct stack of lamellae seen within chloroplasts. Grana contain the pigments, electron transfer compounds, and enzymes essential to the light-dependent reactions of photosynthesis.
mitochondrial matrix
The gel-like material, with considerable fine structure, that lies in the matrix space, or lumen, of a mitochondrion. It contains the enzymes of the tricarboxylic acid cycle and, in some organisms, the enzymes concerned with fatty acid oxidation.
fascia adherens
cell-cell adherens junction that contains the transmembrane protein N-cadherin, which interacts with identical molecules from neighboring cells to form a tight mechanical intercellular link; forms a large portion of the intercalated disc, the struc
intercalated disc
complex cell-cell junction at which myofibrils terminate in cardiomyocytes
residual body
vesicles containing indigestible materials, part of lysosomal digestion
spindle pole body
The microtubule organizing center in fungi; functionally homologous to the animal cell centrosome.
cell projection
prolongation or process extending from a cell, e.g. a flagellum or axon
collagen type II trimer
collagen homotrimer of alpha1(II) chains