The cells of animals, plants, and fungi consist of three main parts: the plasma membrane, nucleus, and cytoplasm. Bacteria differ from them in that they do not have a nucleus, but they also have a membrane and cytoplasm.
How is the cytoplasm arranged?
This is the inner part of the cell in which it is possible to isolate the hyaloplasm (liquid medium), inclusions and organelles (organelles). Inclusions are unstable formations in the cell, which are mainly drops or crystals of reserve nutrients. Organoids are permanent structures. As in the body the main functional units are organs, so in the cell all the basic functions are performed by organelles.
Membrane and non-membrane cell organelles
The first are divided into single-membrane and double-membrane. The last two are mitochondria and chloroplasts. Single membranes include lysosomes, Golgi complex, endoplasmic reticulum (endoplasmic reticulum), vacuoles. We will talk about non-membrane organoids in more detail in this article.
Nonorganic cell organelles
These include ribosomes, the cell center, as well as the cytoskeleton formed by microtubules and microfilaments. Also, organoids of movement possessed by unicellular organisms, as well as male reproductive cells of animals, can be assigned to this group. Let us consider in order the non-membrane organelles of the cell, their structure and functions.
What are ribosomes?
These are non-membrane organelles of a cell that are composed of ribonucleoproteins. Their structure includes two parts (subunits). One of them is small, one is large. In a calm state, they are separated. They connect when the ribosome begins to function.
These non-membrane cell organelles are responsible for protein synthesis. Namely, for the translation process - the connection of amino acids into a polypeptide chain in a certain order, information about which is copied from DNA and recorded on mRNA.
The size of the ribosomes is twenty nanometers. The number of these organelles in the cell can reach up to several tens of thousands of pieces.
In eukaryotes, ribosomes are located both in the hyaloplasm and on the surface of the rough endoplasmic reticulum. They are also present inside two-membrane organoids: mitochondria and chloroplasts.
Cell center
This organoid consists of a centrosome, which is surrounded by a centrosphere. The centrosome is represented by two centrioles - empty cylinders inside, consisting of microtubules. The centrosphere consists of radially microtubules extending from the cell center. It also includes intermediate filaments and microfibrils.
The cell center performs functions such as the formation of a spindle division. It is also the center of microtubule organization.
As for the chemical structure of this organoid, the main substance is the tubulin protein.
This organoid is located in the geometric center of the cell, which is why it has such a name.
Microfilaments and microtubules
The former are actin protein strands. Their diameter is 6 nanometers.
The diameter of microtubules is 24 nanometers. Their walls are made of tubulin protein.
These non-membrane organelles of the cell form a cytoskeleton, which helps maintain a constant shape.
Another function of microtubules is transport; organoids and substances in the cell can move along them.
Organelles of movement
They are of two types: cilia and flagella.
The first to possess such unicellular organisms as ciliates, shoes.
Chlamydomonas have flagella, as well as animal sperm.
Motion organoids are made up of contractile proteins.
Conclusion
As a conclusion, we give generalized information.
Non-membrane cell organelles (table)| Organoid | Cell location | Structure | Functions |
| Ribosomes | Swim freely in the hyaloplasm, and are also on the outside of the walls of the rough endoplasmic reticulum | Consist of small and large parts. The chemical composition is ribonucleoproteins. | Protein synthesis |
| Cell center | Geometric center of the cell | Two centrioles (microtubule cylinders) and a centrosphere are radially outgoing microtubules. | Formation of a spindle of division, organization of microtubules |
| Microfilaments | In the cytoplasm of a cell | Thin strands of contractile actin protein | Creation of support, sometimes - providing movement (for example, in amoebas) |
| Microtubules | In the cytoplasm | Hollow tubulin tubes | Creation of support, transport of cell elements |
| Cilia and flagella | On the outside of the plasma membrane | Made up of proteins | The movement of a unicellular organism in space |
So we examined all the non-membrane organoids of plants, animals, fungi and bacteria, their structure and functions.