Each cell of any organism has a complex structure that includes many components.
Briefly about the structure of the cell
It consists of a membrane, cytoplasm, the organelles that are located in them, and the nucleus (except for prokaryotes) in which the DNA molecules are located. In addition, an additional protective structure is provided above the membrane. In animal cells, this is glycocalyx, in all the rest - the cell wall. In plants, it consists of cellulose, in fungi - of chitin, in bacteria - of murein. The membrane consists of three layers: two phospholipid and protein between them.
It has pores, due to which the transfer of substances in and out is carried out. Near each pore, special transport proteins are located that pass only certain substances into the cell. Animal cell organoids are:
- mitochondria, which play the role of a kind of "power plants" (in them there is a process of cellular respiration and energy synthesis);
- lysosomes that contain special enzymes for metabolism;
- Golgi complex for storing and modifying certain substances;
- endoplasmic reticulum, which is needed for the transport of chemical compounds;
- a centrosome consisting of two centrioles that are involved in the division process;
- the nucleolus, which regulates metabolic processes and creates some organoids;
- ribosomes, which we will discuss in detail in this article;
- plant cells have additional organoids: a vacuole, which is necessary for the accumulation of unnecessary substances due to the inability to bring them out due to the strong cell wall; plastids, which are divided into leukoplasts (responsible for storing nutrient chemical compounds); chromoplasts containing colorful pigments; chloroplasts in which chlorophyll is located and where the photosynthesis process takes place.
What is a ribosome?
Since we are talking about it in this article, it is quite logical to ask such a question. A ribosome is an organoid that can be located on the outside of the walls of the Golgi complex. It is also necessary to clarify that the ribosome is an organoid that is contained in very large quantities in the cell. One can contain up to ten thousand.
Where are these organoids located?
So, as already mentioned, the ribosome is a structure that is located on the walls of the Golgi complex. She can also move freely along the cytoplasm. The third option, where the ribosome can be located, is the cell membrane. And those organoids that are in this place practically do not leave it and are stationary.
Ribosome - structure
What does this organelle look like? She looks like a handset. The ribosome of eukaryotes and prokaryotes consists of two parts, one of which is larger, the other is smaller. But these two of its components do not connect together when it is in a calm state. This happens only when the ribosome of the cell directly begins to fulfill its functions. We will talk about functions later. The ribosome, the structure of which is described in the article, also includes informational RNA and transport RNA. These substances are necessary in order to record on them information about the desired cell proteins. The ribosome, the structure of which we are considering, does not have its own membrane. Its subunits (the so-called two halves of it) are not protected by anything.
What functions does the given organoid perform in the cell?
What the ribosome is responsible for is protein synthesis. It occurs on the basis of information that is recorded on the so-called messenger RNA (ribonucleic acid). The ribosome, the structure of which we examined above, combines its two subunits only for the duration of protein synthesis - a process called translation. During this procedure, the synthesized polypeptide chain is located between the two subunits of the ribosome.
Where do they form?
Ribosome - an organoid that is created by the nucleolus. This procedure occurs in ten stages, during which proteins of the small and large subunits are gradually formed.
How does protein formation occur?
Protein biosynthesis occurs in several stages. The first of these is the activation of amino acids. There are twenty of them in total; by combining them with different methods, you can get billions of different proteins. During this stage amino amino-t-RNA is formed from amino acids. This procedure is impossible without the participation of ATP (adenosine triphosphoric acid). Also, magnesium cations are needed to carry out this process.
The second stage is
the initiation of the polypeptide chain, or the process of combining the two subunits of the ribosome and supplying the necessary amino acids to it. Magnesium ions and GTP (guanosine triphosphate) also take part in this process. The third stage is called elongation. This is directly the synthesis of the polypeptide chain. Occurs by translation method. Termination — the next stage — is the process of the disintegration of the ribosome into individual subunits and the gradual cessation of the synthesis of the polypeptide chain. Next is the last stage - the fifth is
processing. At this stage, complex structures are formed from a simple chain of amino acids, which are already finished proteins. Specific enzymes as well as cofactors are involved in this process.
Protein structure
Since the ribosome, the structure and functions of which we have analyzed in this article, is responsible for the synthesis of proteins, let us consider their structure in more detail. It is primary, secondary, tertiary and quaternary. The primary structure of a protein is a specific sequence in which the amino acids that form this organic compound are located. The secondary structure of the protein is formed from polypeptide chains of the alpha helix and beta folds. The tertiary structure of the protein provides a certain combination of alpha helices and beta folds. The quaternary structure consists in the formation of a single macromolecular formation. That is, combinations of alpha helices and beta structures form globules or fibrils. According to this principle, two types of proteins can be distinguished - fibrillar and globular.
The former include actin and myosin, from which muscles are formed. Examples of the second are hemoglobin, immunoglobulin and others.
Fibrillar proteins resemble a thread, a fiber. Globular are more like a ball of interwoven alpha-helices and beta-folds.
What is denaturation?
Everyone must have heard this word. Denaturation is the process of destroying the structure of a protein - first quaternary, then tertiary, and then secondary. In some cases, the elimination of the primary structure of the protein occurs. This process can occur due to exposure to a given organic substance of high temperature. So, protein denaturation can be observed when cooking chicken eggs. In most cases, this process is irreversible. So, at a temperature above forty-two degrees, the denaturation of hemoglobin begins, so severe hyperthermia is life threatening. Protein denaturation to individual nucleic acids can be observed during digestion, when, using enzymes, the body breaks down complex organic compounds into simpler ones.
Output
The role of ribosomes is very difficult to overestimate. They are the basis for the existence of the cell. Thanks to these organoids, she can create proteins that she needs for a wide variety of functions. Organic compounds formed by ribosomes can play a protective role, transport, the role of a catalyst, a building material for the cell, enzymatic, regulatory (many hormones have a protein structure). Therefore, we can conclude that ribosomes perform one of the most important functions in the cell. Therefore, there are so many of them - the cell always needs products synthesized by these organoids.