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Контрольні запитання



- Які є методи фарбування зрізів і мазків фіксованих тканин?

- Назвіть основні гістохімічні реакції.

- цитохімічні методи вивчення рослинної клітини

- Прокаріотична та еукаріотична клітина: які їх спільні риси, чим відрізняються?

 

Laboratory work № 3.2.

mitosis

purpose
Study of cell division
task
Microscopy permanent and new obtained microspecimens
Theoretical information
Sexual female and male cells are single set of chromosomes and therefore contain 2 times less DNA than other cells. Sex cells (sperm and oocytes) with a single set of chromosomes is called haploid. Ploidity (from the Greek. Ploos-multiplicity) denoted by the letter n, so that cells with 1n - haploid, with 2n - diploid, with 3n - triploid etc. Accordingly, the number of DNA per cell (s) depends on the ploidy: cells with 2n number of chromosomes containing 2c amount of DNA. At fertilization merge two cells, each of which carries 1n chromosomes so produced output dyploydnaya (2n, 2c) cell zygote. Further by dividing diploid zygote and subsequent separation diploid cells develop organism whose cells except sex, are diploid. However, we know that the process of cell division is preceded by phase synthesis, DNA replication, which should lead to the appearance of cells with 4C amount of DNA in which the number of chromosomes 4n, ie twice as much as in the original diploid cell. It was only after the distribution of such tetraploid (4c) cells again have two weekends diploid cells. In interphase nuclei of cells detected by morphological methods body chromosomes is very difficult. Actually chromosome as a clear, dense, highly visible in the light microscope body are only shortly before cell division. In the very same interphase chromosomes as dense bodies are not visible because they are loosened condition. In interphase is doubling reduplication of chromosomes. This period is characterized by the synthesis of DNA, it is called synthetic or s-period. It was at this time in cells is the DNA of more than 2c. After the s-period amount of DNA in the interphase nucleus still 4c, because there was a complete doubling of chromosomal material. However morphologically register doubling the number of chromosomes at this stage is not always possible. Actually chromosomes as filamentous dense bodies begin to appear microscopically at the beginning of the process of cell division, namely prophase mitotic cell division. If you try to count the number of chromosomes in prophase, their number is equal to 2n. But this is a false impression, because in each of prophase chromosomes double as a result of their replication. At this stage the pair of chromosomes is closely connected with each other, mutually spiralizuyas one on the other, it is difficult to see the duality of the entire structure as a whole. Later chromosomes in each such pair begin to be separated, spun. This duality of chromosomes in mitosis is observed even in living cells in late prophase, when it is clear that the total number of chromosomes in a single cell start-share 4n. So, in early prophase chromosomes consisting of two sister chromosomes, or as they are called chromatids.

In prophase, and in the next period of cell division - in metaphase-sister chromosomes remain linked to each other in the form of steam. In metaphase chromosome alignment occurs in the equatorial plane of the cell and their final separation. In prophase and metaphase cells remain tetraploid.
In anaphase is the difference of each pair of chromosomes to opposite poles of the cell then begins to divide the body of the original cell. Then in telophase diverged diploid (2n) set of chromosomes begin decondensate. Some chromosomes lose their distinct shape and is now inside the new interphase diploid nuclei with 2c DNA chromosome hard to recognize that we have seen during mitosis. Thus, one chromosome cycle and the next begins.
Equipment, materials and methods.
Microscope objective lenses, glasses with hole, glass rods, hinges, cover lenses. pipette graded to 2 ml, 5 ml, 10 ml , Goryaev camera, test tubes, Petri dishes, flasks of 100 - 200 ml

 

The order of performance and recommendations
- Obtain samples of living cells and permanent preparations - thin slices of tissues of animals and humans
- If painted by different methods of preparates to prepare for microscopy entire group sections.
- Adjust lighting and image in the microscope.
- Microscopy samples at different stages increase.
- In the study of the internal structure of cells is preferred greatest degree increase, providing immersion lens h90.
- When working with a group of slices visualize the same area, using several preparates that dyed by different methods.
- Micrograph recorded in the minutes of laboratory work, add a massive line.
- Compare observations made with representatives of the various kingdoms of nature: plants, animals and fungi.
- After thoroughly remove excess oil immersion lens of the microscope and preparates.

Control questions
- What are the methods of dyeing sections and smears fixed tissues?
- What are the main histochemical reaction.
- Cytochemical methods for studying plant cell
- Prokaryotic and eukaryotic cells: their similarities are the differences?