Biological molecules, also known as biomolecules, are the fundamental chemical building blocks that compose all living organisms. These organic compounds are primarily made of carbon, hydrogen, oxygen, and nitrogen, along with smaller amounts of other elements. They are essential for carrying out life processes, storing energy, and forming the intricate structures within cells and tissues. They enable growth, reproduction, and the maintenance of life.
Carbohydrates
Carbohydrates are a group of biomolecules that include sugars, starches, and fibers. They are primarily composed of carbon, hydrogen, and oxygen, often with a hydrogen-to-oxygen ratio similar to water. Their main function is to serve as the body’s immediate and primary source of energy. When consumed, carbohydrates are broken down into glucose, which cells use as fuel.
Carbohydrates are classified into three main types. Monosaccharides, like glucose and fructose, are simple sugars. Disaccharides, such as sucrose (table sugar) and lactose (milk sugar), are formed when two monosaccharides link together. Polysaccharides, including starch in plants and glycogen in animals, are complex carbohydrates, serving as energy storage or structural components.
Lipids
Lipids are a diverse group of molecules characterized by their insolubility in water, meaning they are hydrophobic. This group includes fats, oils, waxes, phospholipids, and steroids. Lipids serve multiple roles in living organisms. They are important for long-term energy reserves, providing a concentrated source of fuel.
Beyond energy, lipids are integral components of cellular structures. Phospholipids, for instance, form the double-layered membranes that enclose cells and their internal compartments, regulating what enters and exits. They also function as insulation, protecting organs and maintaining body temperature. Additionally, certain lipids, like steroid hormones such as testosterone and estrogen, act as chemical messengers, coordinating biological processes and signaling between cells, tissues, and organs.
Proteins
Proteins are complex macromolecules constructed from chains of smaller units called amino acids. Approximately 20 different types of amino acids are commonly found in proteins, linked together by peptide bonds. The specific sequence and arrangement of these amino acids determine a protein’s unique three-dimensional structure, which, in turn, dictates its function. Proteins have a vast array of functions.
They act as enzymes, accelerating nearly all biochemical reactions within cells, from digestion to DNA replication. Proteins also provide structural support, forming components like collagen in skin and keratin in hair and nails. Other functions include transporting substances, such as hemoglobin carrying oxygen in the blood, defending the body against pathogens as antibodies, and facilitating cell communication through hormones and receptors.
Nucleic Acids
Nucleic acids, specifically deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are biomolecules that carry and express genetic information. They are composed of repeating building blocks called nucleotides. Each nucleotide consists of three main components: a five-carbon sugar (ribose in RNA, deoxyribose in DNA), a phosphate group, and a nitrogenous base. These molecules are fundamental for heredity and the synthesis of proteins.
DNA serves as the master blueprint, storing the genetic instructions for building and maintaining an organism. Its double-stranded helical structure ensures the stable transmission of genetic information from one generation to the next. RNA, typically a single-stranded molecule, plays diverse roles in carrying out these instructions, including messenger RNA (mRNA) transporting genetic code from DNA to ribosomes, transfer RNA (tRNA) bringing amino acids for protein assembly, and ribosomal RNA (rRNA) forming part of the protein-making machinery.