Proteins are the key group for life as we know it. To understand the role that proteins have in our lives, let's go back to the beginning of life on planet Earth, up to the second Precambrian period, the Archean Eon, successor to the Hadean, which occurred between 3.8 and 2.5 billion years ago. years ago and was divided into four eras: Eoarchean, Paleoarchean, Mesoarchean and Neoarchean.
The Eoarchean Era was marked by the accumulation of rain that gave rise to the hydrosphere, or ocean basins, formed by the condensation of water vapor with the gases that formed the atmosphere (methane, hydrogen, nitrogen and ammonia). As the rain fell on the rocks, they dissolved, salinizing the ocean, creating mineral salts such as: rock salt (sea), calcium, zinc, manganese, iodine, selenium, fluorine, phosphorus, sodium, potassium, chlorine and magnesium.
In the beginning, the waters were shallow and received high amounts of ultraviolet solar radiation, causing the grouping of substances into biomonomer structures (glycine, alanine, urea and formic acid). These primordial substances gave rise to the class of organic substances: proteins, lipids and carbohydrates.
Based on the theory of Haldane and Oparin from 1920 AD, about primitive terrestrial conditions, in 1953 AD, the Miller-Urey experiment was carried out, which recreated the primitive conditions in a controlled environment and allowed the observation of the grouping of amino acids such as glycine and alanine surrounded by water molecules, which gave rise to protocells, or coacervates. Tecnicaly, their emergence ends the Eoarchean Era.
As the primitive ocean was relatively radioactive, the coacervates underwent mutations, giving rise to the first nucleotides, nucleic acids formed by a sugar with a 5-carbon chain (pentose), a phosphate and a nitrogenous base (purine bases adenine, guanine, cytosine, uracil and thymine). The beginning of Paleoarchean Era.
Still considering the radioactive conditions, the nucleotides began to group together within the coacervates that stabilized from a lipid layer that separated the internal environment from the external. This primitive protobiont organism began the process of duplication and, consequently, multiplication, from the nucleotide known as RNA (ribonucleic acid) composed of a filament of riboses (C5H10O5) and phosphates linked to nitrogenous bases adenine, guanine, cytosine and uracil. This molecule, capable of replicating itself but without metabolism (anabolic and catabolic chemical reactions, which produce and use energy), is known as ribozin.
From a mutation, an RNA lost connection with one of the ribose oxygen molecules, becoming a deoxyribose (C5H10O4) that duplicated with other nitrogenous bases (cytosine, guanine, adenine and thymine). This new substance connected with an RNA strand to stabilize itself, giving rise to a unique combination of genes, DNA (deoxyribonucleic acid), or genetic material. A single DNA molecule is a chromosome.
The presence of ribonucleic and deoxyribonucleic acids within the coacervates gives rise to the first prokaryotic cells that contain a lipid and protein membrane (karyoteca) surrounding the genetic material, but do not have a developed nucleus; the place where the genetic material resides is known as the nucleoid.
From the double-stranded DNA, which stores information, RNA synthesizes proteins (nitrogenous bases) and participates in the duplication of genetic material, also known as bipartition or binary fission, as we can see below.
PROTEIN AND THE HUMAN BEINGS
Proteins play a crucial role in human development. They are the basic building blocks of the body's tissues, including muscles, bones, skin, hair and organs. During stages of growth and development, such as childhood and adolescence, adequate protein intake is crucial to ensure healthy growth and proper development of these tissues.
In addition to supporting growth, proteins are also essential for the maintenance and repair of tissues throughout life. They play a vital role in cell renewal, injury repair, muscle regeneration after exercise, and maintaining the structural integrity of vital organs.
Proteins are key components of enzymes, hormones and antibodies that play critical roles in biological processes such as digestion, metabolism, immune response and cellular communication. For example, digestive enzymes break down food into absorbable nutrients, hormones like insulin regulate blood sugar, and antibodies help fight infections.
Although carbohydrates and fats are the main sources of energy, proteins can also be converted into energy when needed. However, the body prefers to use proteins for structural and biological functions, and only resorts to using them as an energy source in situations of extreme need, such as during prolonged fasting or intense exercise with no carbohydrates available.
The human brain is primarily composed of neural tissue, which requires proteins for its proper structure and function. Proteins are essential for the formation and maintenance of synapses, the connections between neurons, which are fundamental for information processing, learning and memory.
Many neurotransmitters, the chemicals that transmit signals between neurons, are composed of proteins or synthesized from amino acids, the basic components of proteins. Neurotransmitters such as dopamine, serotonin and norepinephrine play important roles in mood, motivation, cognition and sleep regulation, among other functions.
Certain proteins act as growth factors that promote the development and survival of neurons. For example, brain-derived neurotrophic factor (BDNF) plays a crucial role in neuroplasticity, the brain's ability to adapt and learn throughout life, and protects neurons from damage and degeneration.
The human body is capable of producing many proteins on its own through internal metabolic processes. However, there are nine essential amino acids that the body cannot produce on its own and that need to be obtained through the diet. These essential amino acids are fundamental for the synthesis of proteins, which in turn play several essential roles in the body.
When we consume foods that contain protein, these foods are digested and broken down into their constituent amino acids in the digestive tract. These amino acids are then absorbed by the body and used in the synthesis of proteins necessary to build and repair tissues, produce enzymes and hormones, maintain a healthy immune system, among other functions.
Therefore, although the human body is capable of producing some proteins internally, adequate protein intake through the diet is critical to ensuring that the body has access to the essential amino acids needed to sustain its vital functions.
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