Nucleoli have a size of 0.5-1.0 μm, contain large amounts of RNA and protein.

Textbook. – K., 2001. Fundamentals of labor protection. – K., 2000. General hygiene and basics of ecology. – K., 2002.

12/31/2011

The role of bacteria and their importance. Abstract

The abstract provides information about the importance of bacteria in nature and human economic activity

The important role of many species of bacteria is due to their participation in the processes of putrefaction and various types of fermentation, ie in the performance of sanitary role on Earth.

Of particular importance are bacteria that decompose cellulose and pectin, which are the main source of carbon for the activity of soil microorganisms.

Sulfate-reducing bacteria are involved in the formation of oil and hydrogen sulfide in therapeutic muds, soils and seas. Thus, a layer of water saturated with hydrogen sulfide in the Black Sea is the result of the activity of sulfate-reducing bacteria. The activity of these bacteria in soils leads to the formation of soda and soda salinization of soils. Sulfate-reducing bacteria convert nutrients in the soils of rice plantations into a form available to the roots of this crop. These bacteria can cause corrosion of metal underground and underwater structures.

Due to the activity of bacteria, the soil is freed from many harmful products and saturated with valuable nutrients. Bacterial preparations are successfully used to control many species of insect pests (corn borer, etc.).

Many types of bacteria are used in various industries to produce acetone, ethyl and butyl alcohols, acetic acid, enzymes, hormones, vitamins, antibiotics, protein and vitamins.

Thanks to advances in genetic engineering, Escherichia coli is now widely used to produce insulin and interferon, and hydrogen bacteria can be used to produce feed and food proteins. Without bacteria, the processes of tanning leather, drying tobacco leaves, making silk, rubber, processing cocoa, coffee, soaking hemp, flax and other fibrous plants, fermenting cabbage, water purification, leaching of metals, etc. are impossible.

literature

Biology. Encyclopedia. – M., 1999. Biology: Textbook. way. / AA Slyusarev, OV Samsonov, VM Mukhin and others; For order. and lane. from the Russians. VO Motuzny. – 3rd ed., Corrected. and add. – Kyiv: Higher School, 2002 .– 622 pp.: Ill. Dictionary of Biology. – K., 2000.

12/31/2011

Living cells, types of forming tissues, the structure of the stamen. Abstract

The main properties of living things. The structure and significance of the nucleus in the cell. Types of forming tissues, their structure and significance in the plant organism. The structure of the stamen and the processes that take place in it

1. The main properties of living things

Reproduction is one of the main properties of living organisms, which ensures the continuity and continuity of life. Like irritability and mobility, the ability to reproduce is a characteristic feature of living things, but is usually observed at a certain period of life. Reproduction is the ability of living beings to reproduce their own kind to sustain the existence of a species.

At the subcellular level, the process of reproduction can be traced to mitochondria and chloroplasts, which are capable of division.

There are two main forms of reproduction of plants and animals: sexual and asexual. There is a fundamental difference between them, which is that in asexual reproduction the new generation originates only from one parent, and the source of the formation of the new generation are somatic (vegetative) cells.

In the case of sexual reproduction, a new organism is usually formed from two parental individuals (male and female). The source of the formation of this organism are special cells, which are called gametes. They differ from somatic cells by a half (haploid) set of chromosomes.

Forms of reproduction of multicellular organisms can be represented by the following scheme:

Spore formation is the reproduction by the formation of special cells from which a new generation emerges. Very common among different types of organisms of the plant world and some animals (spores). However, in bacteria, spore formation is not a way of reproduction, but an adaptation to survival under adverse conditions.

Spores are unicellular formations covered with a strong shell, which protects them from adverse factors and has an adaptive value. Spores in algae, higher aquatic plants and some fungi have motile flagella, so they are called zoospores. In higher plants (mosses, ferns, etc.) spores are formed in special organs – sporangia.

In the case of vegetative reproduction, the new organism originates not from specialized but from ordinary somatic cells. This type of reproduction is especially common in plants.

Some animals (polyps, ciliated worms) are able to reproduce by dividing the whole individual into two or more parts. Many plants and individual multicellular animals (hydra) have been shown to reproduce by budding.

Punching is that on the body of the maternal organism is formed growth – the navel, which can be separated and become an independent individual (hydra), and in some animals (coral polyps, sponges) the navel is not detached from the maternal individual, colonies are formed. In higher plants, vegetative propagation can be carried out in different parts of the plant.

Unicellular organisms (bacteria, protozoa, some algae and fungi) reproduce asexually (dividing them lengthwise, crosswise, repeatedly) and sexually. In this case, the sexual process can occur by copulation or conjugation.

Metabolism is a common property characteristic of all living organisms.

The general biological essence of metabolism as a specific property of living matter is that all living organisms remove from the environment various organic and inorganic compounds and chemical elements, use them in their lives and emit into the environment the end products of metabolism in the form of simple organic and inorganic compounds.

Metabolism can be characterized as a complex of biochemical and physiological processes that ensure the viability of organisms in close contact with the environment. The complex of physiological processes studied at the level of the whole higher organism includes the acts of respiration, nutrition, digestion, absorption, as well as the excretion of metabolic products of organs and systems (skin, lungs, excretory system, digestive system).

The process of protein biosynthesis is a universal type of plastic metabolism for all living organisms. This process occurs intensively during the growth and development of the body (increase in body weight), as well as in those cells that synthesize enzymes, hormones and other proteins. In all other cells, biosynthesis is less intense, but continues constantly, because the cells write my lab reports online regularly break down proteins and need to be renewed.

The most important role in the process of protein biosynthesis is played by nucleic acids – RNA and DNA. DNA itself is not directly involved in protein synthesis because it is located in the nucleus, and the main site of protein synthesis are ribosomes on the endoplasmic reticulum of the cytoplasm.

2. The structure and significance of the nucleus in the cell

All animal cells (with a few exceptions – erythrocytes) and plants have a nucleus. Most cells have a single nucleus, less often two and multinucleated cells. Multinucleated are the cells of some species of protozoa, as well as cells of the human liver, brain and muscles. They often occur due to the fusion of several cells into one. The shape of the nucleus largely depends on the shape and size of the cell.

Usually in spherical cells the nucleus has a rounded shape, in elongated muscle cells the nucleus is also elongated. In some cells, the nuclei may have an irregular shape, for example, in leukocytes horseshoe or lobed nuclei. The shape of the nucleus can change with the age of the cell and depends on its functional state. The size of the nucleus often ranges from 2 to 20 microns. For each cell type, there is a specific nuclear-plasma ratio, the violation of which leads to cell division or death.

The nucleus of an interphase cell is covered with two cytoplasmic membranes, which are absent only during the period of mitotic division. The outer membrane of the nucleus often passes into the membranes of the endoplasmic reticulum and the space between the two nuclear membranes connects with its channel.

Nuclear membranes have pores with a diameter of 80-100 nm. Through them there is an exchange between a kernel and cytoplasm.

The contents of the nucleus are called nuclear juice (karyoplasm). It contains 1-2 nucleoli and a special substance – chromatin (gr. Chroma – color, coloring). This substance is well stained with nuclear dyes. In prokaryotes, chromatin consists only of DNA molecules, and in eukaryotes – of DNA, basic low molecular weight proteins (histones), a small amount of acidic proteins and RNA. In the interphase nucleus, ie in the period between cell divisions, chromatin (interphase chromosome) is in the form of fine diffuse granularity (euchromatin) or thin threads and dense grains of different sizes (heterochromatin).

The ratio of euchromatin and heterochromatin depends on the activity of processes in the cell. The more intense the various processes of synthesis in the cell, the more euchromatin in them, and vice versa. In the process of mitosis, rod-shaped chromosomes are formed as a result of condensation and contraction of thin threads and fusion of individual chromatin lumps. During the interphase in the cell nucleus, complex processes of DNA biosynthesis, which is part of chromatin, as well as mRNA synthesis take place.

Nucleoli have a size of 0.5-1.0 μm, contain large amounts of RNA and protein. They are the site of synthesis of ribosomal and transport RNA, nuclear proteins and ribosomes. During mitosis, the nucleoli disappear and then form again in the telophase. Their formation is associated with the functioning of certain sections of chromosomes (nuclear organizers), specific to each species.

The nucleus is not just an important part of the cell, but the center of control of its life processes – metabolism, movement, reproduction. The main mass of DNA is concentrated in the nucleus, which is the carrier of hereditary (genetic) information, ie the nucleus performs the function of storing information about all the features of the organism, and during cell division transmits it to daughter cells.