Cells of animals, plants and fungi consist of three main parts: the plasma membrane, the nucleus and the 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 hyaloplasm (liquid medium), inclusions and organelles (organelles) can be distinguished. Inclusions are non-permanent formations in the cell, which are mainly drops or crystals of reserve nutrients. Organelles are permanent structures. Just as organs are the main functional units in the body, so in the cell all the main functions are performed by organelles.
Membranous and non-membrane cell organelles
The first are divided into single-membrane and double-membrane. The last two are mitochondria and chloroplasts. Single-membrane include lysosomes, Golgi complex, endoplasmic reticulum (endoplasmic reticulum), vacuoles. We will talk about non-membrane organoids in more detail in this article.
Cell organelles of non-membrane structure
These include ribosomes, a cell center, and a cytoskeleton formed by microtubules and microfilaments. Also to thisthe group can include the organelles of movement, which are possessed by unicellular organisms, as well as the male germ cells of animals. Let's take a look at the non-membrane cell organelles in order, their structure and functions.
What are ribosomes?
These are non-membrane cell organelles that consist 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 ribosomes is twenty nanometers. The number of these organelles in a cell can reach up to several tens of thousands.
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 organelles: mitochondria and chloroplasts.
Cell center
This organoid consists of a centrosome, which is surrounded by a centrosphere. The centrosome is represented by two centrioles - cylinders empty inside, consisting of microtubules. The centrosphere consists of microtubules extending radially from the cell center. It also includes intermediate filaments and microfibrils.
The cell center performs such functions as the formation of the division spindle. It is also the center of microtubule organization.
As for the chemical structure of this organoid, the main substance is the protein tubulin.
This organoid is located in the geometric center of the cell, hence its name.
Microfilaments and microtubules
The first are actin protein filaments. Their diameter is 6 nanometers.
Microtubules are 24 nanometers in diameter. Their walls are built from the protein tubulin.
These non-membrane cell organelles form the cytoskeleton that helps maintain a permanent shape.
Another function of microtubules is transport, organelles and substances in the cell can move along them.
Organoids of locomotion
They come in two types: cilia and flagella.
The first are unicellular organisms such as ciliates-shoes.
Chlamydomonas has flagella, as well as animal spermatozoa.
The organelles of locomotion are composed of contractile proteins.
Conclusion
As a conclusion, we present generalized information.
| Organoid | Cage location | Building | Functions |
| Ribosome | Float freely in the hyaloplasm, and are also located on the outer side of the walls of the roughendoplasmic reticulum | Consist of small and large parts. Chemical composition - ribonucleoproteins. | Protein synthesis |
| Cell center | Geometric center of the cell | Two centrioles (cylinders of microtubules) and centrosphere - radially outgoing microtubules. | Spindle formation, microtubule organization |
| Microfilaments | In the cytoplasm of the cell | Thin filaments of the contractile protein actin | Creating 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 | From the outside of the plasma membrane | Made of proteins | Movement of a unicellular organism in space |
So we examined all the non-membrane organelles of plants, animals, fungi and bacteria, their structure and functions.
