Biochemistry

Another important organelles of the cell are lysosomes (from the Greek. Lysis - dissolution, soma - body). These structures are membrane-limited bodies containing proteolytic enzymes. An intact lysosomal membrane is very strong and resistant to enzymes. They are dangerous for the cell and are enclosed, as it were, in a pouch formed by a membrane. The purpose of lysosomes is diverse: they are able to break down already used proteins, fats, carbohydrates and their intermediates. The lysosome membrane is semipermeable and inhibits the release of enzymes into the cytoplasm, if this is not necessary. When the integrity of the lysosome membrane is violated as a result of any exposure, lysosomal enzymes can destroy the cell. Plant cells contain plastids - small granules with a double membrane, in which the synthesis and accumulation of organic substances occurs. These include chloroplasts, leukoplasts and chromoplasts. Chloroplasts contain the green pigment chlorophyll, which is able to synthesize the energy of sunlight. In chloroplasts, solar energy is converted into chemical energy, which is stored in the form of chemical bonds of various food substances produced during photosynthesis. Leukoplasts are colorless plastids, starch and other substances accumulate in them. Chromoplasts contain various pigments that determine the color of fruits, vegetables and flowers. Nucleus is the main intracellular organelle of the cell, having a spherical shape with a diameter of about 5 microns. It contains at least 95% of all deoxyribonucleic acid (DNA). DNA, together with basic and acidic proteins and a small amount of ribonucleic acid (RNA), make up a complex complex called chromatin. Before the start of cell division, chromatin is assembled into chromosomes, their shape and internal organization are strictly regulated for each type of organism. Molecular elements of chromosomes are unique, they contain specific and individual information. Inside the nucleus, one or more spherical structures of small sizes can be distinguished. These are nucleoli. They contain a lot of RNA. The remaining mass of the core is liquid, it is called nucleosol (nuclear juice). The core contains all the enzymes necessary for the biosynthesis of DNA and RNA. It is a carrier of genetic information (hereditary traits) and controls all types of metabolic activity of the cell. The nucleus is surrounded by a dense double membrane having “ pores ” through which macromolecules and even small particles can pass. The hierarchy of molecular organization of the cell is shown in Figure 1.4. 28