The composition and other characteristics clearly differentiate these two cell types.
Its small size made it impossible to observe and discover it until the microscope was invented.
Thanks to its discovery, the cell theory was elaborated, which postulates that the cell is the structural and functional unit of all organisms, since it can fulfill the three basic vital functions: nutrition, relationship and reproduction. It also contains the genetic material of the organism.
However, cells are not all the same and vary according to different criteria: species, structure, function in the organism…
In this article we are going to see the main differences between prokaryotic cells and eukaryotic cells .
What do eukaryotic and prokaryotic cells have in common?
Although these two types of cells present quite remarkable differences, it is necessary to take into account that they are not radically different from one another, since they present some shared structures and fulfill similar functions.
In both there is genetic material, that is, DNA , although it is presented differently. They are delimited by a cell membrane, composed of a lipid bilayer, and there may also be the presence of a cell wall. Its organic composition is chemically similar, having: proteins, carbohydrates, lipids, nucleic acids, water and minerals.
In both, proteins are synthesized thanks to the fact that they contain ribosomes, and they are involved in metabolic processes, regulating the entry of nutrients and eliminating waste products. As both types of cells are living structures, they require energy to survive.
Differences between eukaryotic and prokaryotic cells
There are certain structures and particularities that make these cells clearly distinguishable from one another.
We will now see more clearly what these differences are.
1. Core
It is considered the main difference between these two cell types . Prokaryotic cells lack a differentiated nucleus, while eukaryotes have a well-defined nucleus, inside which is the genetic material.
However, although they lack a nucleus, prokaryotic cells have a structure that fulfills a function similar to that of this organelle, which is the nucleoid.
2. Origen
It is hypothesized that prokaryotic type cells are older, giving their origin about 3,700 million years ago , while eukaryotic cells would be more recent, appearing about 2,000 million years ago, being descendants of prokaryotes.
In fact, the name given by scientists to these two types of cells takes into account their evolutionary history.
Etymologically speaking, ‘prokaryote’ is broken down into ‘pro’, which comes from the Greek and means ‘before’ and ‘karyon’ which means nucleus, that is, ‘before the formation of the nucleus’. Instead, ‘eukaryote’ comes from the Greek ‘eu’, meaning ‘true’ and ‘karyon’, meaning ‘with a true nucleus’.
2. Size
Prokaryotic cells have a smaller size compared to eukaryotes, being between 0.1 and 5 microns for the former and between 10 and 100 microns for the latter.
3. Cell shape
In the case of prokaryotic cells, they can have various shapes: spherical, rod, orthographic comma-shaped or spiral.
Eukaryotes are even more varied, being able to have spherical shapes, diamond-shaped, as in the case of plant cells, oval, flattened, tadpole like a sperm…
4. Location of genetic material
Eukaryotic cells, having a nucleus, have their genetic material stored in that organelle . In contrast, in the case of prokaryotes, the DNA is scattered throughout the interior of the cell.
Another difference with respect to the genetic material is that in prokaryotic cells, DNA is not associated with histones.
5. Plasma membrane
There are differences in the composition of the membrane depending on the type of cell . In prokaryotes, the compounds of this membrane are peptidoglycan and murein, while in the case of eukaryotes it can be seen that it is composed of phospholipids.
6. Cell wall
The cell wall is a protective structure found in some types of cells . In the case of prokaryotes, they all have this type of wall, while in eukaryotes there are some cells that have it, but it is not always there.
For example, animal cells, which are eukaryotic, do not have this structure, while plant cells, which are also eukaryotic, do.
7. Cell organization
Normally, the species that have prokaryotic cells are usually unicellular, that is, their organism is made up of only one cell .
Instead, eukaryotic cells are usually present in organisms that have more than one cell, making up tissues, organs, and other larger structures.
8. Form of genetic material
There are also differences in the shape of the genetic material depending on the type of cell. In prokaryotes it can be found in a circular shape, as if it were a crown, while in eukaryotes it is presented in a linear or chain shape.
In turn, the genetic material of eukaryotic cells is shown in the form of chromosomes with its most prototypical form: two chromatids, centromere and telomeres.
9. Number of chromosomes
Chromosomes are structures made up of strands of DNA. In the case of prokaryotic cells, due to the simplicity of their genetic material, it is only organized around a single chromosome.
Instead, in eukaryotic cells there can be several pairs of chromosomes , being 4 in the cells of a fly and 23 in human cells.
10. Organizations
Organelles are the structures that can be found in the cytoplasm of cells and their shape varies depending on the type of cell in which they are located.
In the case of prokaryotes, the organelles do not have a membrane, while in the case of eukaryotes they do have a membrane, the clearest example being the Golgi apparatus, both smooth and rough.
11. Cell division
Cell division, also called cell reproduction, takes place in different ways depending on whether the cell is prokaryotic or eukaryotic . This difference stems from the fact that one has a differentiated nucleus while the other does not.
In prokaryotes, cell division occurs directly or binary fission. Neither the mitotic spindle nor the microtubules are formed, structures that do appear in the case of reproduction in the eukaryotic cell.
In eukaryotes, division can occur in two ways: by meiosis or by mitosis.
12. Living beings and domains
Prokaryotic and eukaryotic cells are more common in certain domains.
Prokaryotes belong to the domains of bacteria and archaea, and by themselves, this type of cell is a single living organism. However, although unicellular, they can form colonies of several individuals.
Instead, eukaryotic cells can be found in the Eukarya domain , which is named after that of the eukaryotic cells themselves. Living beings such as plants, animals and fungi present this type of cells which are organized forming the various structures of these organisms.
13. Scourge
The flagellum, also called the cilium, is a structure that can be found in different types of cells, although not all of them can present it.
In the case of prokaryotic cells, the flagellum is simple , made up of flagellian protein. They are usually a few.
On the other hand, in eukaryotes, if there is a flagellum, these are compounds, formed by various types of proteins, including tubulin. There are usually several hundred of them.
Differences between animal cells and plant cells
As we have already mentioned before, within eukaryotes, two types of cells can be differentiated: animal and plant cells . These cells have common structures, since they are part of the same domain, however, there are some aspects that distinguish them from each other.
Both have a nucleus, which is why they are eukaryotes, where the genetic material is found. Their cell reproduction is similar, performing both meiosis and mitosis. They also have common structures with which they can carry out different metabolic processes, necessary for the proper functioning of the organism.
The way they store energy is different. In plant cells, this energy is stored in the form of an organic molecule called starch, while in animal cells it is stored in the form of glycogen. There are also differences in terms of their size, with plants being larger, with a polyhedral shape thanks to the fact that they have a cell wall, unlike animals. Furthermore, plant cells can synthesize all essential amino acids.
One should not fall into the mistake of thinking that plant cells are exclusive to plants. They are also in algae, fungi and archaea, which as we have already mentioned before, the latter are prokaryotic cells. It must be said that fungal cells are, in fact, a kind of combination of characteristics of plant and animal cells.
Bibliographic references
- Alberts et al (2004). Molecular biology of the cell. Barcelona, Spain. Omega.
- Lane, N. (2005). Power, Sex, Suicide. Mitochondria and the Meaning of Life. Oxford, Reino Unido. Oxford University Press.
- Lodish et al. (2005). Cellular and molecular biology. Buenos Aires, Argentina. Pan American Medical.
To the classic question “what do you do?” I always answer “basically I am a psychologist”. In fact, my academic training has revolved around the psychology of development, education and community, a field of study influenced my volunteer activities, as well as my first work experiences in personal services.