Biomolecules are organic molecules produced by living organisms, forming the chemical foundation for all life. They are the building blocks and functional components that enable cells to perform their tasks. These molecules range from small compounds to large macromolecules, collectively forming the complex machinery of life.
Carbohydrates
Carbohydrates are a group of biomolecules encompassing sugars, starches, and fibers. They are composed of carbon, hydrogen, and oxygen atoms, often in a 1:2:1 ratio, giving rise to the name “hydrates of carbon.” These molecules serve as the body’s primary source of energy, fueling cellular processes. Plants store excess glucose as starch, while animals store it as glycogen.
Beyond energy, carbohydrates also contribute to structural support. Cellulose, a complex carbohydrate, is a major component of plant cell walls, providing rigidity and protection. Common examples include glucose and fructose (simple sugars), sucrose (a disaccharide), and starch and cellulose (polysaccharides).
Lipids
Lipids are a diverse class of biomolecules characterized by their insolubility in water. This group includes fats, oils, waxes, and steroids, all sharing largely nonpolar hydrocarbon chains. Their hydrophobic nature allows them to form barriers, such as cell membranes, where phospholipids create a bilayer.
Lipids are important for long-term energy storage. They also provide insulation, protecting organs and helping to maintain body temperature. Steroids, such as cholesterol and hormones like testosterone and estrogen, are types of lipids that act as chemical messengers, regulating physiological processes.
Proteins
Proteins are complex macromolecules constructed from smaller units called amino acids, linked together in long chains. These chains fold into specific three-dimensional structures, directly related to their diverse functions. Proteins are involved in nearly every biological process.
Many proteins function as enzymes, biological catalysts that speed up biochemical reactions, such as food digestion. Structural proteins like collagen and keratin provide support and shape to cells, tissues, and organs, forming components like skin, hair, and nails. Proteins also play roles in transport, like hemoglobin carrying oxygen, and in defense, with antibodies neutralizing foreign invaders. Hormones, such as insulin, can also be proteins, regulating blood sugar levels.
Nucleic Acids
Nucleic acids are biomolecules for the storage and transmission of genetic information. The two primary types are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Both DNA and RNA are polymers made of repeating monomer units called nucleotides. Each nucleotide consists of a five-carbon sugar, a phosphate group, and a nitrogenous base.
DNA stores the genetic blueprint for an organism, containing instructions for building and maintaining cells. In eukaryotic cells, DNA resides primarily in the nucleus. RNA is involved in expressing this genetic information to synthesize proteins. Messenger RNA (mRNA) carries genetic instructions from DNA to ribosomes, while ribosomal RNA (rRNA) and transfer RNA (tRNA) also play roles in protein synthesis.