Ultrastructure of Plant Cells
Botany I. - Introduction to Botany, Algology, Mushroom and Functional Plant Ecology, Sejttan -
2. The "average" plant cell
Most plant and animal cells are not visible to the naked eye. The cells of the higher plants are usually 10-150 μm long. About 200 pieces of average sized plant cells fill a square centimeter. That is why the total number of cells in a whole body is astronomical: for example, an adult pellet contains 50 million cells, while the total fruit tree is over 15 billion.
Some cells have a square shape, while others may vary greatly depending on their location and function. Most of the young cells that make up the green plant part or fruit have a spherical shape, but by the time they reach full maturity they can have up to forty sides.
Of course, the average plant cell does not exist in reality. However, the similarity of plant cells allows us to present a cell with an average composition that contains the cell creators found in all living plant cells. In the case of the average cell, in addition to the similarity, we always have to think about the differences: for example, that the fiber pellets (p. 73) are nuclear-free, there are generally no chloroplasts in the root cells, or the sperm cells are cell-free. (Fiber-tube members are the fused bundle elements of the sperm which are fused together, forming the perforated fiber plate on their end walls.) This composite cell can be simply described; an intermediate space surrounded by a cell wall. protoplasm that can be secreted into cytoplasm and nucleus. A plant cell deprived of the protoplast cell wall, i.e., a membrane-bound protoplasm, is actually a product created in a laboratory and produced for various physiological and biochemical studies. Vacuoles are cellular membrane (tonoplast) -bound cells found in the plant cell, which are called aqueous fluid, the so-called. cellular fluid and dispersed in the cytoplasm of young plant cells. Older plant cells already have a larger central vacuum. Various compounds are found in the vacuoles in water-soluble form, for example: sugars, salts, pigments, intermediate metabolites, or crystals.
From the cell wall, the protoplasm is captured by the plasma membrane (plasma plasma) and the nucleus (nucleus) protected by another membrane system, the core membrane (Fig. I.1a, Fig. I.1b). In the cytoplasm, so-called. cytoplasmic organelles include: mitochondria, plastis, ribosomes, microtubules and microtubes (microsomes). (All of these are described in the rest of this chapter.) There are other membrane structures within the cytoplasm, such as the so-called. endoplasmic reticulum (ER) and mostly Golgi apparatus located near the nucleus. In plant cells, membrane-like vesicles corresponding to Golgi devices of animal cells are also called dicososomes.
The organelles and membrane systems of the cytoplasm (Golgi, ER, etc.) are a so-called. found in the base stock (matrix). This is the cytosine (the soluble phase of the cytoplasm), which is a dense amorphous medium without structure that contains all the compounds necessary for life. Although there are dissolved substances in the cytoplasm, most are natural granular colloids. Therefore, cytoplasm is often referred to as a colloid complex because it exhibits many properties of colloidal systems. The colloidal structure of the protoplasm is largely determined by the proteins present. The enormous surface provided by the proteins creates a medium for the reactions required for adsorption, chemical processes, and ultimately for cell life processes.
Most of the DNA in the cell is found in the nucleus, but it has its own DNA set for plastis and mitochondria.
The most important evolutionary evolution was the formation of differentiated cellular structures (cellular organs, ie compartments) differentiated into cellular functions in cellular organization. Thereby, separate and increased membrane surface reaction spaces were created in which biochemical processes could be performed faster and faster. With the exception of the internal membrane of the plastis and mitochondria in the plant cell, all membranes (Golgi, ER, cornea,…) are part of an endomembrane, a mutually related membrane system that is related to their origin.
Due to intracellular spatial separation (compartmentalization), the concentration of compounds in the cell is often inaccurate since the concentration can only be used to describe homogeneous systems. It is more advantageous if the content = quantity / cell (e.g., nmol cell-1) is used to provide information on the intracellular quantitative conditions of cell-building materials.
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