Organelle is a permanent formation in the cell that performs certain functions. They are also called organoids. Organella is what allows a cell to live. Just like an animal and a man are made up of organs, so every cell is made up of organoids. They are diverse and perform all the functions that ensure the life of the cell: this is the metabolism, and their storage, and division.
What are the organelles?
Organella is a complex structure. Some of them may even have their own DNA and RNA. All cells contain mitochondria, ribosomes, lysosomes, a cell center, a Golgi apparatus (complex), an endoplasmic reticulum (reticulum). Plants also have specific cellular organelles: vacuoles and plastids. Some also include microtubules and microfilaments as organoids.
Organella is a ribosome, a vacuole, a cell center, and many others. Let's take a closer look at the structure and function of organelles.
Mitochondria
These organoids provide the cell with energy - they are responsible for cellular respiration. Plants, animals, and fungi also have them. These cellular organelles have two membranes: external and internal, between which there is an intermembrane space. What is inside the shells is called a matrix. It contains a variety of enzymes - substances necessary to accelerate chemical reactions. The inner membrane has folds - cristae. It is on them that the process of cellular respiration takes place. In addition, the mitochondrial matrix contains mitochondrial DNA (mDNA) and mRNA, as well as ribosomes, which are almost identical to those of 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 ribosome organelle is simpler than the mitochondria - it does not have membranes. This organoid consists of two parts (subunits) - small and large. When the ribosome is inactive, they are separated, and when it begins to synthesize a protein, they are combined. Several ribosomes can also come together if the polypeptide chain synthesized by them is very long. This structure is called a polyribosome.
Lysosomes
The functions of the organelles of this species are reduced to the implementation of cellular digestion. Lysosomes have one membrane, inside which are enzymes - catalysts for chemical reactions. Sometimes these organelles not only break down nutrients, but also digest whole organelles. This can happen with prolonged fasting of the cell and allows it to live for some more time. Although if the nutrients still do not begin to flow, the cell dies.
Cell center: structure and functions
This organelle consists of two parts - centrioles. These are cylindrical formations consisting of microtubules. The cell center is a very important organoid. He is involved in the process of forming the spindle of division. In addition, it is the center of microtubule organization.
Golgi apparatus
This is a complex of disk-shaped membrane sacs called tanks. The functions of this organoid are to sort, store and convert certain substances. Here, mainly carbohydrates are synthesized, which are part of the glycocalyx.
The structure and functions of the endoplasmic reticulum
This 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 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, the beginnings of vacuoles are formed in it - organelles characteristic of plant cells. The rough endoplasmic reticulum contains on its surface ribosomes that produce a polypeptide chain of amino acids. Further, it enters the endoplasmic reticulum, and a certain secondary, tertiary and quaternary structure of the protein is formed here (the chain is twisted correctly).
Vacuoli
These are plant cell organelles . They have one membrane. They accumulate cellular juice. A vacuum is needed to maintain 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 out excess fluid from the cell.
Plastids: varieties, structure and functions
These are also plant cell organelles . They are of three types: leukoplasts, chromoplasts and chloroplasts. The former are used to store spare nutrients, mainly starch. Chromoplasts contain various pigments. Thanks to them, the petals of plants are multi-colored. This is necessary for the body in the first place in order to attract pollinating insects.
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 in which the body receives organic matter from inorganic substances. These organoids have two membranes. The chloroplast matrix is called the "stroma". It contains plastid DNA, RNA, enzymes, as well as starch inclusions. In chloroplasts are thylakoids - membrane formations in the form of coins. Inside them, photosynthesis takes place. It also contains chlorophyll, which serves as a catalyst for chemical reactions. Thylakoid chloroplasts are combined into piles - granules. Also in the organoids are lamellae, which connect separate thylakoids and provide a link between them.
Organelles of movement
They are characteristic mainly for unicellular organisms. These include flagella and cilia. The former are present in euglena, trypanosomes, chlamydomonas. Flagella are also present in animal sperm. Cilia have ciliates and other unicellular.
Microtubules
They provide transport of substances, as well as a constant form of cells. Some scientists do not attribute microtubules to organelles.