The theory cell phone , Applied to biology, is one that identifies and describes the properties of cells. He argues that living organisms can be unicellular or multicellular, that is, they may be composed of a single cell or several cells.
In this sense, the cell is considered as the basic unit of life, which, through a process of partition or cell division, gives way to the existence of new cells.
It is one of the basic principles of biology. The credit for its formulation is given to the German scientists Rudolph Virchow, Matthias Schleiden and Theodor Schwann.
They were the first to postulate the proposition that living organisms are composed of cells.
Among the most important approaches of the cellular theory, we can find that the DNA Or genetic code of individuals is passed from one cell to another during the process of cell division.
Also that all cells have the same chemical composition, and that the energy of the whole body flows through all the cells of the same.
The evolution of the cell theory is a great example of the progress of science in time. This theory is considered by many as a biological generalization that supports the theory of evolution and in turn allows to unify a branch of scientific knowledge that studies the origin of life.
What is the cellular theory? Postulates
The cell theory is a collection of ideas and conclusions about the description and functioning of the cell, contributed by numerous scientists over time.
T Everything we know about the cell has evolved over time, to the extent that new technologies and ways of collecting information have appeared.
Thus, statements about the spontaneous growth of cells have been discredited to the extent that the cell theory has evolved.
Postulates of the cellular theory
The cell theory mainly talks about three fundamental aspects of the cell:
1 - All living beings are made up of cells. Of a single cell - unicellular organisms - or of several - paralellular.
2 - The cell is the smallest biological unit that exists. Vital functions revolve around cells.
3 - All cells come from other cells. Living things originate from cells.
4- Cells are a genetic unit with hereditary material that allows the transmission of genes from generation to generation.
In this way, no matter the size of the living being studied, since, if a sample of tissue is taken from it, it will be seen that it is also composed of millions of cells.
On the other hand, it can be observed that these cells are responsible for giving rise to other cells, through a process of cell partitioning (Wahl, 2017).
History of Cell Theory and Authors
Origin
Cell theory is considered one of the triumphs of biology , For this reason, its history occupies a central position within all the studies of the life.
In this sense, his study began thousands of years ago when Greek civilizations began to question the nature of life.
Thales of Miletus Laid the foundation of the cell theory by stating that all living things were made of different types of water formations. However, this approach did not allow much advance in the understanding of the nature of living organisms.
It was during the eighteenth century that Greek ideas were resumed and Aristotelian approaches to life, as the result of vital forces in charge of activating basic units or essential particles, were resumed.
First Theories: Blood Cells and Fibers
The appearance of the microscope Made possible the study of the cell, opening the possibility to biology to study a surprising new world.
In 1665, Hooke Was the first scientist to have described the cell when examining sheets of a cork tree under the microscope. In this way, the British eminence described the air that filled the air-filled spaces inside the dead cells.
Hooke observed bones and plants before concluding that there were microscopic channels in them that allowed the fluids of the bodies to be driven.
However, Hooke did not realize the importance of his discovery, since his observations were taken up and valued by the scientific community almost 200 years after his death.
Hooke was not the only one who discovered the cells without realizing it. Grew, an English physicist, described the tissue of plants as"bladders"joined together.
On the other hand, in 1670, scientist van Leeuwenhoek described the structure of blood cells, protozoa in water and sperm, not knowing that he was also talking about different types of cells.
The globulists
In 1771, van Leeuwenhoek's findings on the structure of blood cells led to the appearance of a group of scientists called globulists.
They devoted themselves to the study of this biological unit and its behavior when coming into contact with different solutions.
The approaches of the globulist theory are considered today as the precursors of the cellular theory. For example, in the year 1800, Mirabel stated that all the mass that makes up a plant was itself cellular tissue.
On the other hand, in the year 1812, Molden Hawers pointed out that by macerating a living tissue, taking certain care, it was feasible to see how it decomposed, from a cellular tissue to a group of independent microscopic bladders.
Later globulists of the nineteenth century reported and concluded that all the globules found in animal tissue were similar.
Both the most complex and simpler animals are formed of a greater or lesser number of corpuscles. Thus, in the year 1824, Dutrochet stated that all animals have a similar cellular structure.
In 1833, Raspail promoted a similar theory. Therefore, it is considered that both Raspail and Dutrochet inspired Schwann to pose what we now know as the modern cell theory.
All these approaches have in common the fact that they study the cell from a physical and chemical perspective, using phenomena such as crystallization to explain the phenomenon of growth of life.
By the end of the nineteenth century, there were numerous theories about the globules or cells that made possible the structure of all living tissues.
The cell membrane
In 1839, Purkinje attempted to generalize the properties of all living substances, thereby introducing the use of the term"protoplasm", to refer to the primordial unity of life.
Immediately questions arose about the structure of protoplasm, rethinking scientists the possibility that it was surrounded by a membrane.
However, many scholars have debated for years that this protoplasmic unit is actually contained by a membrane. This debate continued until the year 1895, when Overton showed that in fact there was a cell membrane when using a psychological technique.
Overton showed that different types of alcohol (ethers and ketones), with identical osmotic pressure, did not have the same ability to affect a plant as a solution derived from sugar cane.
In this way, he could conclude that there was evidently a barrier that prevented plant cells from being penetrated by alcohol.
Overton also discovered that the composition of the cell membrane should have lipids like cholesterol in its structure, since it was more easily penetrated by dilute lipids than aqueous solutions.
The evolution of the cell theory is an excellent example of the progress of science in time. Within its structuring were postulated several postulates that were then discarded or proved correct.
This theory is considered by many as a biological generalization that supports the theory of evolution and in turn allows to unify a branch of scientific knowledge that studies the origin of life (Wolpert, 1996).
Cellular Processes
The cell
All living organisms of all realms are living beings are composed of cells and depend on them to function properly. The cell is the fundamental unit of life that can only be studied through a microscope.
Vegetable eukaryotic cell.
Not all cells are the same. Two exists Major types of cells : Eukaryotes and prokaryotes. Some examples of eukaryotic cells include animal, plant and fungal cells; On the other hand, prokaryotic cells include those of bacteria and arachnids.
The cells contain organelles or small cellular structures responsible for fulfilling specific functions, necessary for the proper functioning of the cell.
The cells also contain DNA (deoxyribonucleic acid) and RNA (ribonucleic acid), compounds necessary to encode the genetic information in charge of directing cellular activity.
Cellular Reproduction
Eukaryotic cells grow and reproduce thanks to a complex sequence of events known as the Cell Cycle. At the end of the cell's growth cycle, it divides through the process of mitosis or meiosis.
Somatic cells replicate through the process of mitosis, while reproductive cells do so through meiosis. Prokaryotic cells reproduce asexually by means of a process called binary fission.
Some more complex organisms are also able to reproduce asexually. Here you can find plants, algae and fungi whose reproduction depends on the formation of reproductive cells known as spores.
Animal organisms reproducing asexually do so through the processes of fragmentation, regeneration and parthenogenesis.
- Mitosis
Mitosis is the process of cell division most commonly seen in the cells of eukaryotic organisms, such as animals or plants.
This process results in the production of two daughter cells that can be either haploid (with a simple set of chromosomes contained in its nucleus), or diploids (with a series composed of chromosomes contained in its nucleus) (Morphological, 2013).
It is a process that takes place in four stages of development, as follows:
1- Interface: the DNA contained in the stem cell acquires the capacity of being able to divide, in this way, it increases its size and it generates a dividing line in him.
2 - Profase: the cell membrane disappears and the chromosomes intersect in order to give a new identity to each of the resulting parts.
3 - Anaphase: the chromosome pairs resulting from the previous stage are moved independently to each pole of the cell, where they will remain once the partition ends.
4-telophase: finally, the membrane of both cells is formed, resulting in two identical cellular units, each with its own genetic material and independent organelles.
- Meiosis
Meiosis is a process of cell division directly linked to sexual reproduction. Through this process, the cells of both the ovules and the sperm cells reproduce. Like mitosis, meiosis is divided into four stages of development (Definista, 2015).
Cellular respiration and photosynthesis
Cells perform a significant number of processes that are necessary for the survival of any organism.
In this way, they carry out the complex process of cellular respiration through which they take the energy contained in the nutrients they consume.
The Photosynthetic organisms , Including plants, algae and cyanobacteria, are capable of performing a process known as photosynthesis .
During this process, the sun's light energy is converted to glucose. In turn, glucose is the source of energy on which photosynthetic organisms and the organisms that consume them depend.
Endocytosis and exocytosis
Cells also perform the transport task known as endocytosis and exocytosis. Endocytosis is the process of internalizing and digesting substances, as seen in bacteria.
In this way, once the substances are digested, they are expelled from the body by means of exocytosis. This process allows the cellular transport process to occur between cells.
Cell migration
Cell migration is the vital process for the development of the tissues of organisms. Cellular movement is necessary for mitosis and cytokinesis to occur.
Cell migration is possible thanks to the interaction between motorized enzymes and microtubules of the cytoskeleton.
DNA replication and protein synthesis
The cellular DNA replication process is an important function that is needed to carry out numerous processes, including chromosome synthesis and cell division.
Transcription of DNA and translation of RNA make possible the process of protein synthesis in cells (Bailey, 2017).
References
- Bailey, R. (May 5, 2017). ThoughtCo. Obtained from Cell Theory Is a Core Principle of Biology: thoughtco.com.
- Definista, C.M. (March 12, 2015). FROM. Definition of Meiosis: Definition of Meiosis.
- Morphological, B. (2013). Morphology of Vascular Plants. Retrieved from 9.2. Cell Division: biology.edu.ar.
- Wahl, M. (2017). com. Obtained from What is Cell Theory? - Definition, Timeline & Parts: study.com.
- Wolpert, L. (March 1996). The evolution of 'the cell theory'. Retrieved from Current Biology: sciencedirect.com.