What is Cell

The cell is the basic, structural and functional unit of living beings. Inside it are the essential components that make it possible for organisms to develop properly and fulfill their essential functions: respiration, nutrition, reproduction, etc.

Cells have a basic structure made up of a cellular membrane, the cytoplasm containing the components of the cell and the genetic material. The latter can be concentrated in the nucleus, as in eukaryotic cells, or dispersed in the cytoplasm, as in prokaryotic cells.

Cells are classified into two major types:

  • Eukaryotic cells, which are those that have a cell nucleus. In turn, eukaryotic cells can be of the animal or plant type.
  • Prokaryotic cellsThey do not have a cell nucleus.

The word cell comes from the Latin cell, which means “little cell”. The term was first used by the naturalist Robert Hooke in the 17th century. The cell theory was proposed in 1839. by Matthias Jakob Shleiden and Theodor Schwann. Both affirmed that all organisms are made up of cells, which derive from another preceding cell.

cell parts


Parts of a eukaryotic cell

The cell has three basic components:

plasma membrane: also called cell membrane, it protects the cell and at the same time allows contact with the outside.

Cell nucleus: It is present only in eukaryotic cells and is where the genetic material (DNA) is housed. Prokaryotic cells do not have a nucleus, so their genetic material is scattered.

Cytoplasm: It is the gelatinous medium where all the particular elements of each cell float. Other specialized structures of the cell called organelles are found in the cytoplasm of eukaryotic cells. Some of them are:

  • Golgi apparatus: synthesizes the compounds created by the cell and distributes them in the cytoplasm.
  • mitochondria: It is the organelle where the energy required by the cell to fulfill its functions is produced.
  • ribosomesIt is the place where the cell synthesizes proteins.
  • Endoplasmic reticulumIt is the site of protein and fat synthesis.
  • Perixosomes: They are responsible for degrading hydrogen peroxide and oxidizing fatty acids.
  • lysosomes: is where the digestion or degradation of cellular debris occurs.
  • chloroplasts: are exclusive to plant cells and are responsible for the process of photosynthesis.
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cell types

There are two major types of cells depending on whether or not a cell nucleus is present: eukaryotes and prokaryotes.

Eukaryotic cells

Eukaryotic cells are those that have a defined cell nucleus. This cell nucleus is formed by a nuclear envelope where the integrity of the genetic material (DNA) is maintained.

The organisms formed by these cells are called “eukaryotes”, such as animals or plants.

Eukaryotic cells can be of two types:

Animal cell: It is a type of eukaryotic cell that forms the different tissues of animals (muscles, bones, neurons, etc.). The animal cell is composed of the cell membrane, the cytoplasm where the organelles are found, and the cell nucleus.

Plant cell: It is a type of eukaryotic cell that forms the different structures of plants. It differs from the animal cell in that in addition to the membrane, it has another outer protective structure called the cell wall. In addition, it has chloroplasts, which are the structures where chlorophyll is found, the essential component for photosynthesis.

Prokaryotic cells

Prokaryotic cells are those that do not have a defined nucleus, for which the genetic material is dispersed throughout the cytoplasm. They are characterized because their DNA and structure are much simpler than those of eukaryotic cells.

The organisms formed by this type of cells are called “prokaryotes” and are unicellular organisms, that is, they only have one cell, such as bacteria and archaea.

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Cell characteristics

  • contain DNA and RNA: DNA or deoxyribonucleic acid contains information about the functioning of cells and the hereditary transmission of certain characteristics of organisms. While RNA or ribonucleic acid is the component that helps DNA instructions to be understood by cells.
  • Its interior contains fluids: The interior of cells is made up largely of cytosol, a fluid made up of water, proteins and DNA. This fluid surrounds all intercellular structures.
  • They have an outer membrane: its function is to protect the internal structures and at the same time allow communication with the external environment.
  • respond to stimuli: cells are capable of reacting to stimuli generated by hormones, neurotransmitters or other nearby cells, thanks to the receptors they contain in their cell membrane.
  • They adapt: cells can be modified to help organisms adapt to new environments. For example, the cells of a species of freshwater algae can evolve to adapt to increased salinity in the water.
  • Can change: cells can undergo changes in their composition or structure depending on the function they are going to perform in the body. This process is known as cell differentiation. For example, a bone cell (responsible for bone formation) will have a different structure than a muscle cell.

cell function

The cell fulfills three vital functions: it interacts with its environment, reproduces and nourishes itself to obtain energy.

  • relationship function: cells relate living beings with the environment that surrounds them. They do so by recognizing and reacting to external (environment) or internal (other cells or components of the organism) stimuli.

  • playback function: to generate new cells, they must reproduce. And they do it through mitosis, which is when the cell generates two new identical cells, or by meiosis, when the cell generates four different new cells.

  • nutrition function: the cell needs to be nourished by organic matter to obtain energy. When it produces its own organic matter from inorganic matter (carbon dioxide, water, mineral salts) it is called an autotrophic cell, and this is the case with some types of bacteria, algae, and plants. When it gets organic matter from other organisms, then it is a heterotrophic cell. This is the case of animal cells, humans, fungi and some types of bacteria.

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See also: Levels of organization of matter and Characteristics of living things