Organelle is ... Functions, structure of organelles

Organelle is a permanent formation in a cell that performs certain functions. They are also called organoids. Organelle is what allows the cell to live. Just like an animal and a man consist of organs, so each cell consists of organoids. They are diverse and fulfill all the functions that ensure the life of the cell: this is the metabolism, and their storage, and division.

What are organelles?

Organelle is a complex structure. Some of them may even have their own DNA and RNA. In all cells there are mitochondria, ribosomes, lysosomes, cell center, Golgi apparatus (complex), endoplasmic reticulum (reticulum). Plants also have specific cell organelles: vacuoles and plastids. Some also refer to organoids as microtubules and microfilaments.

Organelle is a ribosome, a vacuole, and a cell center, and many others. Let's take a closer look at the structure and functions of the organelles.

Mitochondria

These organelles provide the cell with energy - they are responsible for cellular respiration. They are in plants, animals, and mushrooms. These cell organelles have two membranes: external and internal, between which there is an intermembrane space. What is inside the shells is called the matrix. It contains a variety of enzymes - the substances needed to accelerate chemical reactions. The inner membrane has folds - cristae. It is on them that the process of cellular respiration occurs. In addition, the mitochondrial matrix contains mitochondrial DNA (mDNA) and mRNA, as well as ribosomes, practically similar to those possessed by prokaryotic cells.

Ribosome

This organoid is responsible for the translation process, in which a protein is synthesized from individual amino acids. The structure of the organelles of the ribosome is simpler than the mitochondria, it does not have membranes. This organoid consists of two parts (subunits) - small and large. When the ribosome is idle, they are separated, and when it starts synthesizing the protein - they unite. Also, several ribosomes can be assembled if the polypeptide chain synthesized by them is very long. Such a structure is called a "polyribosome".

Lysosomes

Functions of organelles of this species are reduced to the implementation of cellular digestion. Lysosomes have one membrane, inside of which are enzymes - catalysts of chemical reactions. Sometimes these organoids not only break down nutrients, but also digest the whole organoids. This can happen with a long hunger strike of the cell and allows it to live for some time. Although if the nutrients still do not begin to flow, the cell dies.

Cellular center: structure and functions

This organelle consists of two parts - centrioles. These are formations in the form of cylinders, consisting of microtubules. The cell center is a very important organelle. He participates in the process of forming the spindle of division. In addition, it is the center of microtubule organization.

Apparatus Golgi

This is a complex of disc-shaped membrane sacs, called cisterns. The functions of this organoid are the sorting, storage and transformation of certain substances. Carbohydrates are synthesized here, which are part of the glycocalyx.

The structure and functions of the endoplasmic reticulum

It is a network of tubes and pockets surrounded by a single membrane. There are two types of endoplasmic reticulum: smooth and rough. On the surface of the latter there are ribosomes. Smooth and rough reticulums perform various functions. The first is responsible for the synthesis of hormones, storage and conversion of carbohydrates. In addition, it forms the rudiments of vacuoles - organoids, characteristic of plant cells. The rough endoplasmic reticulum contains ribosomes on its surface that produce a polypeptide chain of amino acids. Further, it enters the endoplasmic reticulum, and here a certain secondary, tertiary and quaternary structure of the protein is formed (the chain is properly twisted).

Vacuoles

These are plant cell organelles . They have one membrane. They accumulate cell sap. Vacuol is necessary to maintain the turgor. She also participates in the process of osmosis. In addition, there are contractile vacuoles. They are found mainly in unicellular organisms living in water bodies, and serve as pumps that pump excess fluid out of the cell.

Plastids: varieties, structure and functions

This is also the organelle of plant cells. They are of three types: leukoplasts, chromoplasts and chloroplasts. The first serve to store spare nutrients, mainly starch. Chromoplasts contain various pigments. Thanks to them, the petals of the plants are multicolored. This is necessary for the body first of all in order to attract insect pollinators.

Chloroplasts are the most important plastids. The largest number of them is in the leaves and stems of plants. They are responsible for photosynthesis - a chain of chemical reactions, during which the organism receives organic substances from inorganic substances. These organelles have two membranes. The matrix of chloroplasts is called stroma. It contains plastid DNA, RNA, enzymes, as well as starch inclusions. In chloroplasts there are thylakoids - membrane formations in the form of a coin. Inside them, photosynthesis takes place. It also contains chlorophyll, which serves as a catalyst for chemical reactions. Thylakoids of chloroplasts are combined into piles - granules. Also in the organelles are lamellas, which connect individual thylakoids and provide a link between them.

Organelles of movement

They are characteristic mainly for unicellular organisms. These include flagella and cilia. The first are present in euglen, trypanosomes, chlamydomonads. Also flagella are present in animal spermatozoa. Cilia have ciliates and other unicellular.

Microtubules

They provide transportation of substances, as well as a permanent form of the cell. Some scientists do not consider microtubules to organelles.