WHAT AND WHAT ARE CELLULAR PROCESSES? - BIOLOGY - 2025

The cellular processes are all mechanisms that take place within the cell and have as object ensure the stability of the body forming. An example of a cellular process is photosynthesis. This takes place in autotrophic organisms (plants, red and brown algae, and some bacteria).

Photosynthesis is a reaction that occurs in chloroplasts (an organelle present in plant cells). Thanks to this process, carbohydrates are created, specifically glucose, which is necessary for autotrophic organisms to grow.

Also, during photosynthesis, oxygen is released into the atmosphere, an element that is used by other organisms to carry out respiration.

Other cellular processes are metabolism, anabolism, catabolism, protein synthesis, nutrition, respiration (both anaerobic and aerobic), mitosis, and meiosis.

Main cellular processes

1- Metabolism

Metabolism is a set of chemical reactions that occur within the body. These reactions are intended to synthesize or degrade substances. In other words, metabolic reactions create or destroy.

Metabolism begins at the cellular level, since it is here that the first reactions that sustain the life of an organism are triggered. Metabolic reactions can be of two types: anabolic and catabolic.

Anabolism

Anabolism is the phase of metabolism in which substances are synthesized or created. It is also known by the name of biosynthesis.

Anabolic reactions make it possible to obtain complex substances from simpler compounds. In order to carry out this synthesis, energy is consumed during these reactions, which is why they are called endergonic.

Thanks to anabolism, organic matter is produced in the form of tissues that supports the growth of organisms. In autotrophic organisms, glucose is created, which is the food of these individuals.

Furthermore, both in autotrophic and heterotrophic organisms, molecules are created that allow energy to be stored. For example, plants produce starch, while animals produce glycogen.

Photosynthesis, protein synthesis, transcription, and translation are some anabolic cellular processes.

Catabolism

Catabolism is the second metabolic reaction. These reactions are of degradation. This means that molecules are destroyed. This is done in order to release energy. For this reason, catabolic reactions are exergonic.

The molecules with the highest amount of energy are those of glucose. This is why the body often resorts to the degradation of this hydrate to generate energy that allows the body to function properly.

2- Photosynthesis

Photosynthesis formula

Photosynthesis (or synthesis from light) is a cellular process that occurs in plants, algae, and some bacteria. This process consists of two phases: a light and a dark one.

In the light phase, sunlight, chlorophyll (a green pigment present in plant cells) and water molecules intervene. What happens is that the light energy is captured by chlorophyll and is transformed into chemical energy.

In chlorophyll, there is a process called excitation, which causes this pigment to lose an electron. To recover the lost electron, chlorophyll breaks a water molecule, takes the necessary element, and the rest is released.

In the dark phase, carbon dioxide (CO2) molecules, water molecules and the chemical energy that was stored in the light phase are involved.

At this stage, the hydrogen from the water joins the carbon dioxide thanks to chemical energy. The result of this reaction is a carbohydrate called glucose.

3- Protein synthesis

This is the process through which proteins are created within the cell. It is a cycle in which deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and proteins intervene.

DNA synthesizes RNA and the latter synthesizes a series of proteins. These proteins will be the triggers for DNA synthesis and so the cycle begins again.

4- Cellular respiration

Cellular respiration is a process that consists of the oxidation of some molecules to produce energy. This can be of two types: aerobic and anaerobic.

Aerobic respiration is that which occurs in higher organisms (plants, animals and fungi). In this, carbon molecules are oxidized thanks to oxygen from the air.

In autotrophic organisms, respiration is made from the oxidation of glucose produced during photosynthesis.

On the other hand, heterotrophic organisms carry out cellular respiration thanks to the glucose obtained by consuming food.

For its part, anaerobic respiration is an oxidation-reduction process in which the oxidant is not oxygen.

This type of respiration is what occurs in the most primitive organisms, especially in bacteria. It can be found in the tissues of other organisms when oxygen is not available.

5- Nutrition

Nutrition is the process through which the cell "ingests" organic matter. This material allows the cell to regenerate, grow and have the necessary raw material for the other chemical reactions that must be carried out in it.

6- Mitosis

Overview of mitosis. Source: Viswaprabha

Mitosis is a process that involves the duplication of the cell nucleus. This consists of four phases: prophase, metaphase, anaphase and telophase.

During prophase, strands of genetic material organize to form chromosomes.

At metaphase, certain structures of the cell (the nucleoli and the cell membrane) disappear. The centriole (another cell organelle) divides in two and each part moves to one end of the nucleus.

At anaphase, the chromosomes divide in half and each half moves to one end.

Finally, in telophase a membrane forms around each end, creating two nuclei that contain the same genetic information.

7- Meiosis

Summary scheme of meiosis: 1) Duplication of chromosomes 2) Pairing of homologous chromosomes 3) Crossing over 4) First meiotic division (one of each of the duplicated chromosomes per daughter cell) 5) Second meiotic division (one chromosome from each one per daughter cell) (Source: Peter coxhead via Wikimedia Commons)

Meiosis is another cell division process in which haploid cells are formed, that is, with half the genetic load of the stem cell. This process takes place in organisms with sexual reproduction.

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