Did you know that all cells today evolved from the same common cell? The amazing world of cells, studied by a specific branch of science, cell biology, allows us to better understand the characteristics of the basic unit of life: the cell.
With the help of microscopy, it is possible to describe the variable appearance and function of cells, as well as understand their basic properties, allowing scientists to distinguish between two types of cells: prokaryotes and eukaryotes. Here we will tell you the difference between eukaryotic and prokaryotic cells, and a little about the world of cells.
Introduction: difference between eukaryotic and prokaryotic cells
The key difference between eukaryotic and prokaryotic cells depends on their size and the presence or absence of certain organelles and cellular structures.
- In general, we can determine that eukaryotic cells are larger (greater than 10 micrometers) and more complex than prokaryotic cells, which are less than 10 micrometers in size and simpler in structure.
- El core, is where the DNA that defines the cell. It exists only in eukaryotic cells, as does the cytoskeleton and other organelles like mitochondria, chloroplasts, and vacuoles.
- On the other hand, the way of life independent unicellular organisms is characteristic of prokaryotic cells. While in the eukaryotic cells some are unicellular live freely and others are complex multicellular organisms.
- Another aspect of the distinction between these cells is the reproductionProkaryotic cells always reproduce asexually, while in eukaryotes there are two types of cell reproduction processes: asexual and sexual.
Similarities Between Eukaryotic and Prokaryotic Cells
In addition to the differences observed in the previous point, there are some similarities between eukaryotic cells and prokaryotic cells that we are going to mention below:
- Both eukaryotic cells and prokaryotic cells are the basic and fundamental units of life on Earth. Due to this fact, each of the different unicellular and multicellular organisms were able to evolve and colonize the different habitats on Earth.
- These two cell types are characterized by a structure delimited by a membrane that contains in its interior its DNA or genetic information. And different enzymatic mechanisms that allow them to carry out their vital functions: feed, grow and reproduce.
- Eukaryotic and prokaryotic cells, to survive and evolve, They continually convert energy from one form to another. In addition to maintaining a continuous relationship with their exterior in response to the different chemical-biological information they receive from their environment.
What is the prokaryotic cell?
Its name is derived from the Greek word "pro", which means "before", referring to its existence prior to the appearance of other eukaryotic cell types. If we look at the evolutionary history of organisms, prokaryotic cells are the most diverse cells and also the simplest and oldest.
The different prokaryotic cells that live in almost all habitats on Earth belong to the kingdom of monera, which are bacteria (eubacteria) and archaea (bows).
Characteristics of the prokaryotic cell
In order to see inside the prokaryotic cells you need to do it with a electronic microscope, because it is the one with the highest resolution. Prokaryotic cells have the simplest and smallest structure. The interior of the prokaryotic cell is based on:
- Plasma membrane. Like all cells, it is surrounded by a membrane. It contains folds called lamellae. This structure gives the cell a high capacity to exchange common substances with other organisms through them.
- mesosomes. Invaginations of the plasma membrane, which is related to cell division.
- Cellular wall. It is the outermost layer of the cell, and gives it protection.
- Cytoplasm. This is the internal environment in the cell. It has a watery-viscous nature. This is where the organelles and chemical molecules of the cell are located.
- nucleoid. The densest area of ​​the cytoplasm where the cellular DNA, or genetic material, is found. Unlike in eukaryotic cells, the DNA here is not separate from other parts of the cell.
- Ribosomes. These structures have the function of making molecules such as proteins. They can be free in the cytoplasm, or forming groups (polyribosomes).
- Cilia, flagella or fibrils. They are external structures of the cell, which allows them to move.
Su morphology It is variable (spherical, spiral or rod, etc.). And the nature of their reproduction is asexual, which causes them to divide very quickly.
What is the eukaryotic cell?
The meaning of eukaryote comes from the Greek, where "Eu" means "true" and "karyon" means "core". In this way, the main characteristic that defines a eukaryotic cell is presence of a true nucleus in its cellular structure, which defines and keeps the cell's DNA organized. In addition to being larger in size, they are more complex in their morphology and function.
Characteristics of the eukaryotic cell
The characteristics of eukaryotic cells we find that they have an extensive and complex system of organelles. Some organelles are exclusive to animal or plant cells, and others are common to both.. Next, we are going to mention the main ones:
- Plasma membrane. Outer boundary of the cell. Its function is the exchange of molecules and chemical substances between the outside and inside of the cell. It is formed by a double layer of phospholipids and proteins. There are two types of membrane proteins:
– Transmembrane proteins: traversing the lipid bilayer from side to side. They have different functions, for example, the transport of substances and molecules from outside the cell.
– Peripheral proteins: they only communicate with the inner or outer side of the cell. - Cell nucleus. It is where the DNA or genetic material of the cell is found. It is separated from the cytoplasm by the nuclear membrane, this being double.
- Nuclear membrane. It is the structure that separates the cell nucleus from the rest of the cytoplasm. It has holes, called nuclear pores, that allow the exchange of molecules.
- nucleolus. It is the innermost part of the nucleus. It is responsible for the manufacture of the components that make up the ribosomes.
Chromosomes, what are they?
They are found inside the nucleus, and swith the units that make up DNA. In the core are coiled the histones (proteins) and the DNA thus forming the chromatin.
During most of the cell's life cycle, chromatin is in a dormant state. But at some point, it begins to twist and compact. DNA wraps itself and proteins so many times that it looks like a solid. It is as if you took a meter of wire and started to wrap it as tightly as possible. They end with a small, very compact ball. In this new compact state, the chromatin reorganizes into many compact bodies called chromosomes.
Therefore, being composed of DNA, contain genetic information. For example, on one of the chromosomes you would find information about hair color, on another it might be information about body length, and so on.
Each organism contains different genetic information, and the number of chromosomes will be typical of a species.. In humans, each cell in our body contains 46 chromosomes. Close relatives of chimpanzees have 48 chromosomes in their cells. It is worth noting that in eukaryotic cells, the number of chromosomes is always even. There are two identical sets of chromosomes, and chromosomes with the same size, shape, and genetic information are grouped into pairs called pairs of homologous chromosomes or homologous pairs.
Other membrane-bound organelles of eukaryotic cells
La inner membrane of eukaryotic cells determines the different environments in which the different functions take place. It's like a factory, performing tasks in different places to increase efficiency. Among the membrane-bound organelles is the endoplasmic reticulum (ER). It has the appearance of a labyrinth, and its membrane is associated with the nucleus. Distinguish the lattice regions associated with ribosomes.
The ribosomes they adhere to the outer surface of the reticular membrane, giving it a rough or granular appearance. The reticular region associated with the ribosome, which has the function of making proteins, is called rough or granular endoplasmic reticulum (RER or REG). The part of the lattice that does not contain ribosomes is called smooth endoplasmic reticulum (SER) and, among other things, it has the function of manufacturing lipids.
El Golgi complex it is another organelle that is shaped like a stacked membrane sac. Some of the proteins produced in the RER arrive here and are modified. Products go to different destinations: the Golgi apparatus is the supervisor of the transport of proteins produced by cells.
Some go to the plasma membrane, some proteins will be exported to other cells, while others will be packaged in little membrane sacs called vesicles. The lysosomes they are a special type of vesicles formed in the Golgi complex that contain enzymes that play a role in the degradation of organic molecules entering cells. This process is called cellular digestion.
Mitochondria
They are surrounded by a double membrane. The inner membrane of the mitochondria has numerous folds called crests. In the mitochondrial matrix molecules are found DNA and ribosomes. In the mitochondria, chemical reactions are carried out that allow the production of chemical energy from organic molecules in the presence of oxygen. This energy is what sustains all the vital processes of the cell.
Chloroplasts
only exist in plant cells. It has an outer membrane, an inner membrane, and a third type of membrane in the form of flattened sacs called thylakoids They look like stacked plates. Each of these stacks is called grana. The thylakoids contain clorofila, a green pigment that allows the process to take place photosynthesis process.
vacuoles
They are membranous vesicles present in animal and plant cells. However, they are most important in plant cells. They can occupy up to 70-90% of the cytoplasm. In general terms, its function is storage.
Ribosomes
They are organelles formed from two subunits (major and minor) that originate in the nucleolus, and once in the cytoplasm, they are assembled to perform their functions. The ribosomes are responsible for producing or synthesizing proteins. They release them into the cytoplasm or bind to the surface of the RER.
Cytoskeleton
In the cytoplasm of eukaryotic cells, there is a distinct set of filaments that make up the cytoskeleton, and these filaments are needed to maintain cell shape and hold organelles in place. It is a very dynamic structure as it is constantly organizing and disintegrating, allowing cells to change shape (for example, for those that have to move) or organelles to move within the cytoplasm.
centrioles
They are two structures formed by filaments and found in the cytoplasm of animal cells. They are involved in cell division.
Cellular wall
Unique to plant cells. It is located outside the plasma membrane and provides protection. Its composition is different from that of the cell wall of prokaryotic cells. The deposition of certain compounds on the cell wall gives plant parts the stiffness and hardness features of, for example, tree trunks.
I hope this information has been useful to you, and you can learn more about prokaryotic and eukaryotic cells.