- Прокаріотична та еукаріотична клітина: які їх спільні риси, чим відрізняються?
Laboratory work № 3.3.
Regulation of cell division. Mitosis. Meiosis. Amitoz (straight hem) cells. Purpose Study of cell division
Task Investigation ongoing and living micropreparations.
Theoretical information Direct cell division or amytoz reliably described only in the distribution of polyploid macronuclear ciliate, their mikronukleusy divided only by mitotic. The simplest type of mitosis - plevromitoz. He somewhat resembles a binary distribution of prokaryotic cells in which the nucleoid after replication remain associated with the plasma membrane, which begins like to grow between the points of binding DNA and thus, as it carries chromosomes in different parts of the cell (see the division of prokaryotes . below). Then the formation of cell constriction each DNA appears in a new separate cage. As already mentioned, the characteristic division of eukaryotic cells is the formation of the spindle, built with microtubules. When closed plevromitoze (closed he called that discrepancy chromosome is without prejudice to the nuclear envelope) as a microtubule organizing centers (TSOMT) involved not centrioles, and other structures that are on the inside of the nuclear membrane. This so-called polar bodies uncertain morphology, from which the microtubules. These cells twice, they differ from one another without losing the connection with the nuclear membrane, and as a result formed two poluveretena associated with chromosomes. The whole process of the formation of the mitotic apparatus and chromosome occurs in this case, the nuclear membrane. This type of mitosis occurs among the simplest, it is widely distributed in fungi (hitridievye, zihomitsety, yeast, oomitsetamy, ascomycetes, miksomitsetov etc..) There are forms of half-plevromitoza when the spindle poles formed the nuclear membrane breaks. Another form of mitosis is ortomitoz. In this case TSOMT located in the cytoplasm, from the very beginning is not poluvereten education, and bipolar spindle. There are three forms ortomitoza outdoor (normal mitosis), half-closed and closed. In semi-enclosed ortomitoze formed bisimmetrichnoe spindle using TSOMT located in the cytoplasm, nuclear membrane persists throughout mitosis, except for the polar areas. As TSOMT here can manifest weight granular material or even centrioles. This form of mitosis occurs in green algae hreharin, brown, red algae, some lower fungi. When closed ortomitoze completely preserved nuclear envelope, which is formed during this spindle. Microtubules formed in karyoplazme, rarely grow from intranuclear TSOMT unrelated (unlike plevromitoza) nuclear membrane. This type of mitosis characteristic separation mikronukleus ciliates, but found in other protozoa. With an open ortomitoze nuclear envelope breaks down completely. This type of cell division characteristic of living organisms, some of the simplest and the cells of higher plants. This form of mitosis in turn represented astral and anastralnym types. From this brief review shows that the main feature is the occurrence of mitosis do spindle structures division, formed in connection with various in their structure TSOMT. The degree of clustering, condensation of chromatin in the interphase nucleus can be expressed in varying degrees. So intense was divided in specialized cells of the nucleus with diffuse structure in them except for a narrow peripheral rim of condensed chromatin found a small number of small chromocenter, the primary part of the core is occupied by a diffuse, dekondensirovannym chromatin. In addition to highly specialized cells or in cells that complete their life cycle, chromatin represented as a massive peripheral layer and large chromocenter, blocks of condensed chromatin. Such a structure with, for example, the nucleus normoblasts (one of the stages of differentiation of red blood cells), the nucleus of mature leukocytes. These two examples may illustrate the general rule: the more condensed chromatin core particle, the lower the metabolic activity of the nucleus. When natural or experimental inactivation of nuclei is progressive condensation of chromatin, and, conversely, when activated nuclei increased proportion of diffuse chromatin.
Equipment, materials and methods. Microscope objective lenses, glasses with hole, glass rods, hinges, cover lenses. pipette graduated to 2 ml, 5 ml, 10 ml, camera Goryaeva, test tubes, Petri dishes, flasks of 100 - 200 ml
The order of performance and recommendations - Obtain samples of living cells and tissues. - Prepare for microscopy native (unpainted preparates) types "hanging drop" and "crushed drop." - Prepare smears and other preparations for painting. - Fix samples chemically and thermally - Conduct coloring technique. - These preparates microscopy. To fix the image on all available degrees of increase, from less to most. - Compare appearance of cells fixed and painted and native. - Set clear image of moving the condenser. - Compare observations made with representatives of the various kingdoms of nature: plants, animals and fungi.
Control questions - What are the methods for staining chromosomes? - What are the main histochemical reaction. - Cytochemical methods for studying plant cell - Prokaryotic and eukaryotic cells: their similarities are the differences?