The cell is a minimal anatomical unit from which all living organisms are formed, whose functions are nutrition, relationship with the environment and reproduction. They are divided into two types: eukaryotic cells and prokaryotic cells.
Most cells have three basic parts: the nucleus (except for prokaryotic cells), the cytoplasm, and the plasma membrane. Along with these elements are the cytoskeleton, organelles and the cell wall (the latter present only in certain types of cells).
Basic structure of a eukaryotic animal cell.
The nucleus is an internal structure unique to eukaryotic cells. There is the genetic material of multicellular living beings. It is bounded by a membrane, and is surrounded by the cytoplasm.
- coordinate the work of all organelles of the cytoplasm,
- coordinate cell reproduction,
- store the genetic information of the individual.
- Nuclear membrane: coating of the nucleus.
- Nucleoplasm: internal and fluid substance of the nucleus, containing various structures. Its function is to store the nucleolus and chromatin.
- Nucleolus: its function is to program the formation of ribosomes that are then transported outside the nucleus and assembled in the cytoplasm.
- Chromatin: they are structures made up of proteins and deoxyribonucleic acid (DNA). They shape chromosomes.
See also Cell nucleus.
Cytoplasm and some of its organelles (animal cell).
The cytoplasm is the watery or gelatinous medium inside the cell. It is made up of two fundamental elements: the cytoskeleton and the organelles.
In the particular case of prokaryotic cells, devoid of a nucleus, the cytoplasm is responsible for carrying the genetic material, made up of a single DNA molecule.
The cytoskeleton is a dynamic filament structure present in the cytoplasm of all types of cells. The cytoskeleton is in constant transformation, so it is not a finished structure. The function of the cytoskeleton is to give shape, consistency and dynamism to the cytoplasm and, consequently, to the membrane.
Organelles of the cytoplasm
Organelles, also called organelles or organelles, are small organs contained in the cytoplasm that carry out specific functions. The number and variety of organelles depends on the type of cell and its function. Some of the better known organelles are:
Ribosomes: unique organelles present in all types of cells. They possess two subunits of ribosomal ribonucleic acid (rRNA). Its function is to synthesize enzymes and other protein substances.
Endoplasmic reticulum (ER): membrane system that carries proteins. It is divided into rough ER, whose function is to receive proteins, and smooth ER, whose function is to create a new membrane.
Golgi apparatus: formed by sacs close to the nucleus. Its function is to process the molecules transported by the ER and accumulate them in small vesicles that release their content to the outside of the cell.
Lysosomes: made up of membranous walls that form "digestive bags" when they are put into operation. Its role is to digest the material that the cell ingests.
Mitochondria: they are two membranous sacs whose function is to produce energy for cellular work through chemical reactions. Each mitochondrion has a mitochondrial chromosome, that is, its own DNA cell.
Vacuole: compartments of eukaryotic plant cells that store fluids such as water and can contain enzymes and nutrients.
Plastids: organelles only present in plant cells. They are responsible for functions such as photosynthesis, the storage of starches and the synthesis of various materials. These include chloroplasts, amyloplasts, and leukoplasts.
Peroxisome: vesicle-shaped organelles, responsible for the oxidation and elimination of hydrogen peroxide.
Centrioles: pair of organelles in the form of a rod and crossed with each other whose function is to participate in cell division.
Flagellum: unique prolongation of the cell whose function is to facilitate its propulsion.
Cilia: thin and multiple extensions on the cell surface whose function is to facilitate the movement of cells and fluids.
All cells have a plasma membrane, also known as the cell membrane or plasmalemma. The membrane is the boundary of the cell.
Function of the plasma membrane
- Keep the cell stable.
- Choose the molecules that enter or leave it.
- Establish communication with other cells.
Structure of the plasma membrane
- Phospholipids, types of fat molecules that make up the fabric of the membrane.
- Cholesterol, a type of fat responsible for stabilizing membrane phospholipids.
- Proteins, a type of molecules that act as receptors for others and are also capable of identifying cells from the same individual.