Biomolecules: what are they, types, functions and characteristics?
Let's see what are the characteristics of biomolecules and their main types.
Life, at the zoological level, refers to the set of parameters that differentiate animals, plants, fungi, protists, archaea and bacteria from the rest of natural realities, or in other words, from the abiotic (non-living) portion of ecosystems. Knowing that a rock is not alive is straightforward, but where, for example, would viruses fall? What about viroids and prions, basic infectious agents that are little more than a strand of RNA or a misfolded protein?
It is not our intention to get entangled in metaphysical issues, but it is necessary to know that what generates life, in many cases, is not at all clear. Beyond homeostasis, growth, reproduction and differentiation, there are few better definitions to define life than the following: "that which happens between the states of birth and death".
In any case, if there is one thing that all living things have in common (apart from the presence of at least one cell), it is that they are composed of 4 essential bioelements: carbon, hydrogen, oxygen and nitrogen. Based on these 4 chemical pillars, arise all the biomolecules that make up each of our cells and, therefore, make life on planet Earth possible. If you want to know everything about this topic, continue reading.
What are biomolecules?
Biomolecules are the chemical chemical compounds that form the living matter of all the beings that inhabit the Earth.. They result from the union of bioelements by chemical bonds, among which covalent bonds stand out. These universal biomolecules are amino acids, carbohydrates, lipids, proteins, vitamins and nucleic acids.
These molecules are constantly repeated in all living beings present on the planet, something with very clear implications.This has very clear implications. Given this scenario, there are 2 possible options: either all living beings come from the same common ancestor or, failing that, different types of living beings with the same chemical composition have appeared independently throughout history, which is highly improbable.
Here comes into play the principle of Ockham's razor, which states the following: of two theories with equal conditions, the simpler one will surely explain the problem posed. Thus, the existence of biomolecules in a homogeneous form in all taxa confirms, in the most rational way possible, that all living beings have radiated from the same ancestor.
Before getting ahead of ourselves with complex topics, we think it would be interesting to dedicate a little space to bioelements, the pillars on which biomolecules are supported at the chemical level. We will be quick.
The bioelements are chemical elements that are present in all living things, either in atomic form or as constituents of biomolecules.. Although more than 60 elements from the entire periodic table can be found in the tissues of living beings, only 25 are universal and inalienable.
Moreover, 96% of the mass of almost all cell bodies corresponds to only 6 bioelements: carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P) and sulfur (S), or CHONPS, for the friends of mnemonic rules.
These 6 elements are the basis of biomolecules, due to the following properties they present:
- They allow the formation of covalent bonds between them (they share electrons). These bonds are very stable and enable the formation of biomolecules.
- Carbon atoms can form three-dimensional skeletons, which allows living beings to present very different compounds based on their carbon skeleton.
- Bioelements allow the formation of double and triple bonds between them, as well as the synthesis of various structures (branched, cyclic, etc.).
- A large number of functional groups with different chemical and physical properties can be synthesized with just a few bioelements.
On the basis of all these premises, everything from the simplest bacterium to the entire human organism is built. After all, we must not lose sight of the following fact: biological complexity is determined by cell number and organization, but the basal substrate is always the same..
Types of biomolecules
Here is a list of the types of biomolecules present in the body of all living beings.
Amino acids and proteins
Amino acids are organic molecules with an amino group (-NH2) at one end and a carboxyl group (-COOH) at the other end. They are the basis of proteins, although they can also perform other functions in the human body.. An example of this is GABA (γ-aminobutyric acid), since it is an amino acid that is not present in our proteins and also acts as a neurotransmitter in the nervous system.
There are many types of amino acids, but only 20 of them code for the proteins of living organisms.. A protein is such when the chain of amino acids linked together exceeds 50-100 units or, failing that, reaches a mass of 5000 amu (unified atomic mass unit). Proteins are also considered as biomolecules themselves (although larger and more complex), so they can be included in the same category as the biomolecules that make them up.
Glucids (also known as carbohydrates) are biomolecules well known for their importance in nutrition, as they include free sugars, starch, glycogen and many other substances.. They are always associated with a high energy content (1 gram provides 4.5 kcal), so they are linked to the storage and burning of energy in most living beings. Without going any further, in humans, the largest short-term energy reserve is not fat tissue: it is actually glycogen.
Because of its excellent energetic properties, the World Health Organization (WHO) estimates that approximately 55-60% of a human being's total caloric intake should be carbohydrate-based. Achieving this value is not difficult, as carbohydrates such as starch are found abundantly in bread, corn, potatoes, rice, cereals, legumes and many dairy products.
Lipids are generally known as fats, consisting mainly of carbon, hydrogen and, to a lesser extent, oxygen.. This heterogeneous group includes fats or oils, phospholipids and fatty acids (saturated, monounsaturated and polyunsaturated).
Foods high in lipids should account for 30-35% of the total caloric intake, so, contrary to what many people believe, fats are not bad per se. Human fat tissue has hormonal properties, allows for long-term energy storage, protects us against mechanical damage and much more.
Vitamins are very different compounds that are essential for life.. These substances are generally known as "micronutrients" because, although they are necessary in minute quantities, they perform a series of tasks in our organism that cannot be substituted by other compounds. Vitamin A, vitamin C and vitamin E are clear examples within this group.
5. Nucleic acids
Nucleic acids do not require presentationWe are talking about DNA and RNA. The former is the library of life, since it contains all the genetic information necessary for cell metabolism and, therefore, the survival of all our cells, organs and tissues.
DNA also contains the basis of heredity and evolution, since it is thanks to DNA that mutations occur and traits are inherited that change the genotype and phenotype of species over time.
6. Inorganic biomolecules
As their name suggests, are not organic in nature, but still play a key role in the formation and maintenance of organisms.. A clear example of an inorganic biomolecule is water (H20), which accounts for 70% of the total cell weight.
As you have seen, defining the term "life" becomes a little easier when we understand that, at the end of the day, we are all a conglomerate of 25 organic compounds, especially 6 bioelements: carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P) and sulfur (S). When we reduce morphological complexity to its minimum, we discover that a bacterium and a human cell have almost more similarities than differences.
After all, almost everything around us is carbon and other organic elements, in one form or another. From the tuber of a plant to the liver of a human being there are thousands of years of evolution involved, but also a similar functionality and a similar chemical composition at the elemental level.
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(Updated at Mar 28 / 2023)