What is a PROCARIOT cell
All living things on Earth, from tiny bacteria to humans, are made up of cells.The cell is the structural and functional unit of all living beings, but two types of cells are distinguished: the eukaryotic cell, much more complex and which forms the higher organisms (plants, fungi and animals) and the much simpler prokaryotic cell that forms microorganisms, such as bacteria In this lesson from a TEACHER we will talk about what is a prokaryotic cell. If you are interested in knowing more, join us in this article!
Index
- What is the prokaryotic cell? Easy definition
- Structure of prokaryotic cells
- Facultative elements of prokaryotic cells
What is the prokaryotic cell? Easy definition.
Prokaryotic cells are the functional and structural unit that make up microorganisms. The structure of this type of cells is much simpler than eukaryotes, since they do not have a cell nucleus that protects the genetic material (which is dispersed in an area of the cytoplasm) or specialized organelles in different functions as happens in the eukaryotic cell. In addition, the organisms that are made up of this class of cells are unicellular, that is, they are made up of a single cell.
Etymologically, the word prokaryotic comes from the union of the terms pro which means 'before' and kario which means 'core'. Therefore, according to both terms, a prokaryotic cell would be anterior to the nucleus and it is so, since these cells are the most primitive that inhabit the planet and that formed the basis for the later appearance of eukaryotic cells.
This fact can be verified observing the fossil record from the Precambrian era, which are about 3 billion years old. Prokaryotic cells have been able to survive to this day thanks to the great simplicity of their structures, allowing you to have a flexible physiology to adapt to any type of environment environment.
The ecological importance of prokaryotic cells is that they are part of the main organisms that contribute to the degradation of matter organic on our planet and organisms that are capable of fixing atmospheric nitrogen in their structures and incorporating it into compounds organic.
Structure of prokaryotic cells.
The prokaryotic cell It is made up of constant elements (which are always there) and optional elements (which are not always there).
Constant elements are:
Cellular membrane
It is found separating the internal environment of the cell from the external environment and is a semi-permeable barrier that allows the entry and exit of water and substances, such as the incorporation of nutrients or the exit of waste cell phones. The membrane is made up of lipids and proteins, but unlike eukaryotic cells, they do not have cholesterol.
Cellular wall
The cell wall is a rigid and resistant layer that surrounds the cell membrane, giving the cell a defined shape and an additional layer of protection. It is made up of amino sugar units linked together. The possession of a cell wall is common with algae, plants and fungi, although their composition is different. There are various antibiotics, such as penicillins, that inhibit the formation of this wall and help us fight against bacteria.
Cytoplasm
It is a gelatinous substance that forms the interior of cells. It has embedded in it some substances necessary for cells, such as energy reserve materials or the genetic material of the cell.
Nucleoid
Although prokaryotic cells do not have a defined nucleus, there is a very dispersed region of the cytoplasm where a single circular DNA molecule is found (it can be associated with RNA and proteins). This DNA molecule is essential for the cell, such as allowing its reproduction.
Ribosomes
They are structures formed by proteins and RNA that allow the translation of genetic information into the proteins required to carry out different biological processes.
Facultative elements of prokaryotic cells.
The facultative elements of prokaryotic cells are:
Prokaryotic inclusions
They are inclusions and reserve materials that are found in the cytoplasm of the cell and have specific functions in its metabolism. Not all are always present. Some examples are chlorosomes (they act in photosynthesis), magnetosomes (they allow orientation according to the Earth's magnetic field), carboxysomes (they allow the fixation of carbon dioxide), etc.
Flagella
A whip-like protein structure that allows the cell to move, acting as a kind of propellant tail.
Outer membrane
It is an additional membrane outside the cell wall that characterizes gram negative bacteria. They are important because a molecule sits on them that acts as a powerful toxin for humans.
Capsule
Layer formed by polymers secreted by the cell itself and deposited outside the cell wall. It fulfills functions of protection, adhesion to surfaces or as a food deposit.
Plasmids
They are circular non-chromosomal DNA molecules that in some bacteria accompany chromosomal DNA and replicate independently. They code for antibiotics, resistance factors, or toxins.
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