What is the origin of Extrusomes?
Extrusomes are nasty membrane-bound structures released by ciliates and flagellates. They come in a number of varieties, the best studied being the trichocysts of paramecia. These can be discharged by the thousands per cell in response to physical stimuli, including when attacked by predators.
What is Haptocysts in protozoa?
These are supported by microtubules and phyllae, and have toxic extrusomes called haptocysts at the tip, which they attach to prey. They then suck the prey’s cytoplasm directly into a food vacuole inside the cell, where they digest and absorb its contents.
What are trichocysts used for?
It is thought that the function of trichocysts is to repel predators, though the evidence for this is not very clear. Trichocysts are found in ciliates and in dinoflagellates and other flagellate groups (Hausmann and Hülsmann, 1996).
What is Haptocysts?
Haptocysts are found in the tips of the feeding tentacles of Suctoria (Fig. 19). Prey (mostly other ciliates) which touch the feeding tentacles are caught and held by the extrusion of the haptocysts (Fig.
What is a Toxicyst?
toxicyst In certain protozoa, an organelle which resembles a trichocyst but in which the filament carries a poison that can kill other protozoa. Toxicysts are used for capturing prey. A Dictionary of Zoology.
What is a Cytoproct in biology?
The anal pore or cytoproct is a structure in various single-celled eukaryotes where waste is ejected after the nutrients from food have been absorbed into the cytoplasm.
What is Podophyra?
Podophyra is a ciliate protozoan, which means it is in the same phylum as good old Paramecium. I say phylum and I must qualify this statement. Ciliates are single-celled organisms that until recently were classified as a subphylum within the phylum Protozoa.
What is the definition of trichocysts?
trichocyst, a structure in the cortex of certain ciliate and flagellate protozoans consisting of a cavity and long, thin threads that can be ejected in response to certain stimuli. Trichocysts may be widely distributed over an organism or restricted to certain areas (e.g., tentacles, papillae, around the mouth).
What is Cytostome in biology?
A cytostome (from cyto-, cell and stome-, mouth) or cell mouth is a part of a cell specialized for phagocytosis, usually in the form of a microtubule-supported funnel or groove.
What are Trichocysts in paramecium?
trichocyst, a structure in the cortex of certain ciliate and flagellate protozoans consisting of a cavity and long, thin threads that can be ejected in response to certain stimuli.
What is cytostome in paramecium?
Cytostome is a narrow aperture in the cell membrane of Paramecium through which food particles enters into the cell.
What are the characteristics of extrusomes in protozoa?
Although they have different type-specific structures and functions, they all exhibit one general characteristic: they are readily discharged when subjected to a wide range of stimuli. This chapter describes the structural and functional diversity of extrusomes in protozoa.
What is protozoa?
Protozoa (meaning “first animals”) are heterotrophic, single-celled or colonial eukaryotes. Individuals are microscopic and range in size from a few to hundreds of micrometers, depending on the species.
What is the function of extrusomes?
Extrusomes are associated with the membrane of many protozoa and contain material that can be ejected from the cell. Some extrusomes secrete an amorphous material that is involved in formation of a capsule or cyst, and others discharge a pointed projectile that may serve for protection or predation.
What are extrusomes and exocytosis?
Extrusomes are vesicles containing an organized substance that usually changes its form when the vesicle undergoes exocytosis and releases its contents to the exterior of the cell, often within milliseconds (Hausmann, 1978).
