Living things are made up of cells, the basic unit of life. There are many types of cells:
- according to the origin in evolution: prokaryotic and eukaryotic cell;
- according to energy needs: plant and animal cell;
- according to their functions: muscle cell, epithelial, adipocyte, fibroblast, immune cells, red blood cells, bone cells, among others.
Here are the main types of cells in living things.
The prokaryotic cell is characterized by presenting the genetic material, dispersed in the cytoplasm, ie it has no nucleus. It is the cell that distinguishes the dominis Bacteria i Archaeawidely distributed throughout the biosphere.
The prokaryotic cell has two main structures: the plasma membrane and the cytoplasm. Most are small and simple.
For example, the Staphylococcus aureus It is a rounded bacterium that can be found on the skin and mucous membranes of humans.
The eukaryotic cell is characterized by the presence of genetic material (DNA) confined to the nucleus, a membranous compartment within the cell.
The eukaryotic cell defines the control Eukarya, where animals, fungi, plants, and protozoa are classified.
Eukaryotic cells are larger and more complex than prokaryotic cells, and can be found in unicellular (such as yeast) or multicellular (such as worms) beings.
The eukaryotic cell has three main structures:
- The plasma membrane: is the structure that surrounds and limits the contents of the cell.
- The core: is the organelle that hides the genetic material of the cell.
- The cytoplasm: is the portion of the cell between the nucleus and the plasma membrane, where the rest of the organelles are located (mitochondria, ribosomes, vesicles, among others) and the aqueous medium where they float.
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The plant cell is a type of eukaryotic cell. It is characterized by having structures capable of obtaining energy from sunlight, so they are autotrophic.
The leaves of plant leaves, such as Elodea canadensis, are specialized in capturing sunlight and absorbing carbon dioxide from the air, for the synthesis of carbohydrates. All plants are autotrophic beings, that is, they are independent of other organisms to obtain their energy.
The plant cell has the following structures:
- Plasma membrane: envelope of lipids and proteins that hides the cell contents.
- Core: compartment where the genetic material is located.
- Cytoplasm: half aqueous where the organelles are located.
- Cellular wall: structure that covers the outside of the plasma membrane, composed mainly of cellulose fibers, which supports the cell.
- Chloroplasts: organelles in the cytoplasm with a double membrane, where the process of photosynthesis takes place, that is, the transformation of solar energy into sugars.
- Plasmodesmata: are pores or passages that exist in the cell wall that allows the exchange of material between plant cells.
- Glyoxisomes: are organelles found in seeds, where they store and degrade the lipids needed in the germination process.
- Central vacuole: water storage area inside the plant cell.
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The animal cell is a type of eukaryotic cell that is characterized by its dependence on nutrition from external sources. Therefore, they are heterotrophic.
The animal cell has a plasma membrane that delimits the cytoplasm, where the nucleus and other organelles, such as ribosomes, lysosomes, and mitochondria, are located.
The animal cell is distinguished from the plant cell by:
- Absence of chloroplasts: the animal cell does not perform photosynthesis, so it does not have photosynthetic organelles or chloroplasts.
- Cholesterol in the cell membrane: Cholesterol is obtained in the membranes of the animal cell, which is not found in plant cells.
- Absence of cell wall: the plasma membrane of the animal cell is devoid of a cell wall.
- Presence of centrosomes: structures that play a role in the process of cell division.
Among the diversity of animals that populate the Earth, one of the easiest cells to distinguish at first glance is the eggs. Some have a stiff protective cover, such as birds’ eggs. Others are naked, as are the eggs of amphibians and fish.
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Main types of cells in the human body
Within the human body, there is a great diversity of cells with specific functions.
Epithelial cells are found covering the outside of the body (in the skin) and the inner surfaces (such as the inside of the mouth and nose). They can be flat, cubic or cylindrical, depending on the fabric that is part of them. They are strongly connected to each other, without intercellular spaces. Its main function is to act as a protective barrier.
Adipocytes are the storage cells of lipids and are found in connective tissue and adipose tissue. They are very large and round, with a thin line of cytoplasm around a large fat vacuole.
The fibroblast is the cell responsible for the formation and maintenance of connective tissue. They are also active in the healing and repair of wounds. They are large, flattened and tapered, with an oval, flattened core.
Monocytes and macrophages
Monocytes are cells in the immune system that grow in the bone marrow and are released into the bloodstream. After a short time, the monocytes leave the blood vessels and penetrate the tissues, transforming into macrophages.
Muscle cells are mainly characterized by their ability to contract. They are elongated in the direction of the movement they perform. They are found in skeletal muscle, heart muscle and smooth muscle.
Red blood cells
Red blood cells, red blood cells or erythrocytes are the cells that carry oxygen to all parts of the body. They are characterized by being donut-shaped and have no nucleus, as they lose it when leaving the bone marrow where they occur. Its main function is the exchange of gases:
- the transport of oxygen from the lungs to the tissues and
- the removal of carbon dioxide from the tissues to the lungs.
There are several types of cells in the bones:
- The cells osteoprogenitors appear in the fetal stage in areas of bone growth;
- the osteoblasts they are the bone-forming cells;
- the osteocytes they are the cells that maintain bone quality;
- the osteoclasts they are the cells that degrade bone.
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