Cell: origin, types, parts, functions and characteristics

We explain what a cell is, its discovery and how it is classified. We also explain its general characteristics, functions and more.

What is the Cell?

The cell is the minimum known form of organization of lifethat is, there is no living organism smaller than a cell (viruses are smaller, but there is disagreement about their origin and whether or not they are “living” beings). They all meet the requirements of nutrition, relationships and reproduction of themselves.

According to the cell theory proposed in different measures by scientists of the 17th, 18th, 19th and 20th centuries, but accepted as true since 1838, All living beings in the world are made up of cellsorganized at different levels of structural and functional complexity.

The discovery of the cell is considered the first great step in the modern study of life, since allowed us to understand the complexity of the body of living beings and laid the foundation for numerous sciences to come.

Discovery of the cell

The discovery of cells wine given by the advancement of optics and the invention of the microscope, which allowed us to explore the reality of things imperceptible to the naked eye.

In 1665 the scientist Robert Hooke published the first observations of plant tissues like cork, thanks to microscopes of moderate magnification (50 times) invented by himself.

It was Hooke who coined the term “cell.” (from Latin cellulae: “cells”), due to the shape similar to the cells of a honeycomb that they had.

Types of living beings

Based on the study of the cell, it was possible to distinguish between two forms of living beings: unicellular or simple, and multicellular or complex.

Unicellular. Your body is made up of a single cell, which performs all the functions of a living being.
Multicellular. They have bodies composed of abundant cells, organized into tissues and performing specific functions that, together, keep the individual alive and allow it to grow and reproduce. They are not colonies of cells, but organisms composed of many cells.

Cell function

The functions of the cell may include the following:

Structural functions. Like fat, muscle and bones, which constitute support tissues for the body and its organs.
Secretory functions. That is, the production of substances necessary for life and its self-regulation, such as mucous membrane or gland cells.
Metabolic functions. Energy management. They are responsible for breaking down nutrients or transporting them throughout the body, such as digestive cells or red blood cells, which carry oxygen in the blood.
defensive functions. Since they serve to cleanse the body and defend it from external agents and diseases, like white blood cells.
Control functions. Like neurons, which allow the body to be coordinated and its parts articulated in an orderly manner, transporting information and generating specific reactions.
Reproductive functions. They are used to combine with other cells from a different organism and produce a new individual that has a genetic mixture of the two, as is the case with eggs and sperm.

cellular tissues

The cells in multicellular organisms they do not operate independentlybut jointly and coordinated, and to do so they sacrifice some vital functions in favor of an important specificity.

Thus, there are muscular tissues (muscles), adipose tissues (fats), bone tissues (bones), etc.

Parts of the cell

Cells have different parts, as well as organelles that operate inside them like the organs do within the human body. Some of these parts are:

Plasma membrane. Cells have a membrane that delimits them and distinguishes them from the outside, which has the property of allowing the entry and exit of substances as desired. Thus, the cell can let in nutrients and excrete waste or residue.
Cellular wall. Some types of cells (plants and fungi) have, in addition to their membrane, a cell wall that gives them rigidity and resistance, made of resistant substances such as polymers and sugars.
Core. Not all cells have a nucleus, but those that do concentrate all their genetic material (DNA) in it. It is surrounded by a nuclear membrane.
Cytoplasm. The interior of the cell is called cytoplasm, and is made up of water and other structural substances that allow it to be sectorized and divided, as well as providing space for organelles.
Organelles. The different “organs” of the cell, which fulfill specific roles. Some of them are:
- Mitocondia. Responsible for managing the cell’s energy.
- Lysosomes. Responsible for the processes of digestion and use of nutrients.
- Chloroplasts. Exclusive to plants, they have the chlorophyll necessary for photosynthesis processes.
- Ribosomes. They are responsible for the synthesis of proteins essential for the growth and reproduction functions of the cell.
- Flagella. Some cells have organelles called flagella that propel them through the environment. They are typical of unicellular organisms and mobile cells such as spermatozoa.
- Rough endoplasmic reticulum (RER). Protein synthesis.
- Smooth endoplasmic reticulum (SER). Synthesizes lipids.
- Golgi apparatus. It is vital in the synthesis of many of the cell’s proteins and lipids and functions as a packaging plant: it synthesizes, packages and distributes the substances generated by the cell to their respective destinations in the cytoplasm.

Cell types

There are numerous types of cells, too many to list them all. However, the most important cell classifications are the following:

According to its core. This is a fundamental and very important distinction in the history of evolution, since it distinguishes two great superkingdoms or domains of living beings, which are:
- Prokaryotes. Cells lacking a nucleus, whose genetic material is dispersed in the cytoplasm. They are almost always simple unicellular organisms.
- Eukaryotes. Those cells that have a defined nucleus where their DNA is. They are a step ahead of prokaryotes in evolutionary matters, and allow a greater range of specificity and complexity of life.
According to his kingdom. Traditionally, this distinction between known types of life distinguished only two classes, but today we know that there are many more. Commonly, we speak of:
- Vegetables cells. Belonging to plants and photosynthetic beings.
- Animal cells. Belonging to animals that breathe oxygen and move in space at will.
- Fungal cells. Belonging to molds and fungi of the kingdom fungi.

Cell size

The size of the cells can be very varieddepending on the functions it performs and the degree of complexity it possesses.

Some can be practically visible to the naked eye, while others do not. Their average size is estimated to be around 10 µm (micrometers).

Cell reproduction

Cell reproduction can be of two types:

Sexual. It involves the exchange of genetic material from two cells to create a new one with half the DNA of each.
Asexual. A cell divides without the participation of another cell, into two genetically identical cells.

It may help you: Sexual and asexual reproduction.

Importance of the cell

The cell is the minimum unit of life. endowed with reproductive capacity and autonomy. This means that it is the fundamental, primordial portion of all known life and that without it, it would not have arisen as we know it.

acellular life

There are life forms without cells, but they are few. Viruses, prions and other simple forms of life usually pathogenic (disease-causing).

There are debates in the scientific community regarding the origin of these beings, since some propose that they are de-evolved cells and others maintain that they are forms of life prior to this one.