P. caudatum is a more common form of protozoa, the scientific name paramecium caudatum, under the cilia in the taxonomic classes, film export orders, paramecium families, large paramecium is. It lives in freshwater ponds in general, the small rivers that are being collected.
Cylindrical tubular body of P. caudatum, more rounded front end, in the back of the wide, back-end more pointed, shape it like a straw sandals lying down, so called paramecium. Its body covered with longitudinal rows of cilia, the body's front end from the beginning, there is a central body Erdaogou stretched sideways, back in the groove of a mouth, it is called oral groove. Ditch mouth a cell mouth, pharynx cells attached below. When it is swimming, when the cilia are the body rhythmically swing. Since the existence and where oral groove cilia long, powerful swing, so the paramecium's body will be spinning forward.
The body is full of large paramecium cytoplasm, when forward in the water, it kept swinging mouth ditch the cilia, to muster the water vortex, the water uptake of bacteria or other organisms, food by the cell and into the mouth and pharynx cell cytoplasm, food vacuole formation. Food vacuole with the cytoplasm of the flow in the body moving, gradually soak the food in the digestion and absorption of food residue from the back of the body's cell anal body. Paramecium breathe through the surface membrane, absorbing the water of dissolved oxygen, decomposition of organic matter after the release of energy, carbon dioxide and some nitrogen waste excreted through the surface membrane.
There is a large nucleus cytoplasm in Paramecium is the hub of its life, usually of a large nucleus, a small core, there are two or more small nuclei. Whether the sexual reproductive process of its reproduction and sexual reproduction in two forms. Interestingly, the nuclear cycle of 24 hours a day changing: the smallest at 12 noon, then gradually increased to 24 midnight, when the volume becomes maximum.
Scientists observed under the microscope, normal in the day, the big paramecium substances in the body through contact and exchange of mating, mating rhythm affected by the white. If you use different wavelengths of light exposure paramecium, you can change its mating rhythm, from a different time to start a new cycle. If you put it in the long dark environment, this clock will lose its role, it can easily mate at what time. But as long as it is placed in the sun, just after a very short time, they will automatically correct the clock, but also in the normal mating time was.
Because of its larger individuals of P. caudatum, the typical structure, breed quickly, observe the convenient, easy to collect training, it is generally used it as a good study of cellular genetic material. For years, scientists have used it to study the genetics of the cytoplasmic, cytoplasmic and nuclear interactions in the inheritance, as well as changes in other cell types, made a lot of scientific results. With the development of science, it is also found in many important medical value, for example, with its water-soluble extract, can be more accurately diagnose digestive system diseases such as cancer and breast cancer.
(A) Habitat and morphology
Live in fresh water. General pond, creek can be taken to.
Paramecium shaped like sandals. Body covered with longitudinal rows of cilia. Starting from the front of the body of a stretch diagonally Erdaogou the central body, in the ditch after the end of a mouth, so called the oral groove (oral groove). Swimming, the body of the cilia swing rhythm, due to the existence and where oral groove cilia long, powerful swing, so the worms rotate forward. Surface of the worm surface membrane (pellicle), the differentiation of the cytoplasm outside the ER and quality.
(B) of the surface membrane and its structure
(C) of the cilia and the movement
The structure of cilia and flagella the same. Each root of cilia in the surface membrane from the matrix under a given come, seen under an electron microscope, the matrix of each issue a fine fibers (called cilia small root ciliary rootlet), extends forward for some distance and with a small row of cilia Root linked up to become a bunch of longitudinal fibers, known as dynamic fibrils (kinetodesmas). Combined with the cilia also have a very complex system of small fibers (fibrillar system) to form a variety of small-fiber network, and some scholars as their role is to transfer the impulse and coordinate the activities of cilia; also suggested that ciliary beat coordinating role and it has nothing to do with the membrane potential change.
(D) of the cytoplasm and organelles
Endoplasmic more particles, can flow, within its nucleus, food vacuole, stretching bubble and so on. Macronucleus of P. caudatum has a small core, large core is transparent under the microscope slightly kidney-shaped structure, a small nucleus located in the recess of a large nucleus, large nuclear chief operating nutrient metabolism. Is polyploid, the main pipe small nuclear genetic (and some species have two or more small nuclei). Food vacuole formation in the oral groove of the back-end with a cell population, under which even a funnel-shaped cell pharynx (cytopharynx) also known as the mouth, pharynx in the cell groups with special cilia continued swing, can lead to flow into the cell population by water flow to bring food (such as bacteria or other small organisms and decaying organic matter), in the swallow end of intracellular formation of vesicles, gradually swell into vesicles within the cytoplasm is the food vacuole. food vacuole formed in the body flow have a fixed line, in the flow process, the lysosome fusion in the food vacuole, digestion within the food vacuole. The residue from the body can not digest the rear of the cell anal (cytoproct) discharge. Anal cell usually difficult to see. Such as yeast or bacteria to Congo red staining fed with Paramecium, you can see food vacuole formation and flow in the body.
(E) flexible foam and water regulation
Including the quality and the external mass stretching between the two bubbles, one in front of a body back in the body. Each retractable bubble out into the surrounding cytoplasm arranged collection tube radiation. In the electron microscope, these collection tube ends and the endoplasmic reticulum similarities with the small tube. Bubble in the expansion and collection of the main bubble tube has shrinkage yarn (contractile filament), some people think it is a bunch of microtubules (microtubules) form. Contraction due to shrinking wire water collected in the endoplasmic reticulum (of which there are metabolic waste) into the collection tube, stretching into the main bubble bubble, through the surface membrane hole (or vent) from the body. Stretching before and after the two bubbles constantly alternating contraction of excess water from the body to regulate water balance.
(F) Respiratory
Respiration primarily through inhalation of surface oxygen, exhaling carbon dioxide.
(G) reproductive
Asexual reproduction is transverse binary fission. Divide small nuclear first mitosis, the nuclear row Amitosis large, then the middle horizontal constriction parasites. Divided into two new individual.
Sexual reproduction is conjugation: |
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