the Cage of a green plant. The summary

you are: the Cage of a green plant

Almost all large organisms consist of the microscopic units named cages in which smaller units - organelly contain. Investigating a difficult structure of cages, biologists immobilizujut (fix) them by means of any chemical clamp, fill in in the corresponding environment - in paraffin or plastic, prepare thin cuts by means of microvolume, paint these cuts the various dyes, giving the chance to reveal those or other structures, and then study them or in the light microscope providing thousandfold increase, or in an electronic microscope at increase approximately a million times. to understand to itself a chemical role and to define character of biological activity of the investigated structural units, each of such units is required to be received in the pure state and in enough considerable quantities. With that end in view usually destroy a great number of cages, and then allocate each type organell from received gomogenata in the form of a deposit which is dropping out at tsentrifugirovanii with gradually increasing number of turns. Besieged by such way organelly it is possible then to collect and subject to the analysis to study their chemical nature and to reveal biochemical activity peculiar to them.

Vegetative cages in diameter about 50 microns contain a kernel in which there is a most part of the hereditary information of a cage. This information is stored here in the form of the deoxyribonucleic acid (DNA) concentrated in palochkovidnyh structures, named chromosomes. At each cellular division (mitosis) of a chromosome share, being split on all length in two thanks to what both daughter cells receive identical number of chromosomes and qualitatively identical DNA to Sexual reproduction precedes special reduktsionnoe division (mejoz), leading to occurrence gaploidnyh cages, i.e. Cages with twice smaller number of chromosomes, than in usual diploidnom a set. When these sexual cages (gametes) in the course of fertilisation merge in a zygote, diploidnoe the number of chromosomes is restored.

Separate sites of a molecule of DNA - genes - define the nature of cellular fibers. It is coded in them by means of a specific arrangement of four kinds nukleotidov in which molecule one of four nitrogenous bases contains: adenin (timin (), guanin (G) or tsitozin (). Consistently located three nukleotida define, what of twenty amino acids will join in growing polipeptidnuju a chain. Fibers are synthesised on a surface of the ribosomes constructed of two subparticles and consisting in basic from the ribonucleic acid (RNK) and fiber. Chains are attached to ribosomes special information, or matrix, RNK (mrnk). These chains mrnk are synthesised on DNA-matrix in the course of a transcription and bear in itself the basic information concluded in DNA, but already written down by means of another nukleotidnogo the alphabet, namely alphabet RNK. The third type RNK is transport RNK (trnk). transportaja RNK joins separate amino acids and the ribosome - mrnk where the given amino acid joins in the course of translation in growing polipeptidnuju a chain consisting of amino acids, connected peptidnymi communications transfers them to a complex.

Many of synthesised fibers - enzymes, i.e. Specific catalysts of certain cellular reactions. Enzyme can be presented one only fiber or it can consist of fiber and attached to it rather ' small kofermenta which structure includes certain metals or vitamins. One enzymes contain in organellah, and others are present at a free kind in tsitoplazmme cages.

Vegetative cages are surrounded by the semifixed cellular wall constructed in basic from the cellulose, but containing also various gemitselljulozy, zheleobraznye pectinaceous substances (fastening cages with each other), lignin (in odrevesnevshih fabrics) and suberin (in bark cages).

From within the cellular wall is adjoined by selectively nontight plasmatic membrane - plazmalemma, surrounding all cytoplasm n consisting of fibers and fosfolipidov. Separate organelly, for example hloroplast (the photosynthesis centres) and mitohondrii (in which breath process proceeds), also are surrounded by a membrane. Almost all parts of a cage are penetrated by system interconnected sekretornyh membranes - endo-plasmatic retikulum. Piles membrannyh disks - device Goldzhi or diktiosomy, - take part, apparently, in formation vakuolej, also limited to a membrane (tonoplastom) and various organic various organic and inorganic substances. Internal structure of membranes study a freezing method - etchings. Cages thus freeze and split a blunt knife. They break up along natural surfaces, usually along membranes. After that ice delete sublimation under vacuum and the bared sites napyljajut coal or metal.

In hloroplastah and mitohondrijah there is a DNA which together with nuclear DNA defines a full set of the enzymes responsible for carrying over elektronov from more restored to more oxidised carriers. During this process there is a storage of energy in the form of special chemical svja aej adenozintrifosfata (ATR). ATR it is synthesised from adenovindifosfata (ADP) and inorganic phosphate (P1). In the additional phosphatic communication arising at this reaction, just that energy which is liberated at carrying over elektronov also is reserved. Subsequently at disintegration ATR on ADP and P1 the energy concluded in the third phosphatic communication, again is liberated. Thus, function ATR consists in delivering energy for that chemical work which should be made in a cage.