Biomolecules are organic molecules fundamental to all life forms, from single-celled bacteria to complex multicellular animals. They contain carbon atoms, often bonded with hydrogen, oxygen, and nitrogen, forming structures essential for biological processes.
Fundamental Role in Life
Biomolecules are the foundation of life, serving as building blocks and functional machinery within all living cells. They enable processes that sustain organisms, from generating energy to maintaining cellular structures. These molecules store and transfer genetic information, facilitate metabolic reactions, and provide structural support for tissues and organs. Their diverse actions are central to understanding how living systems operate.
The Core Categories
Carbohydrates
Carbohydrates are a diverse group of biomolecules primarily composed of carbon, hydrogen, and oxygen atoms. They serve as a primary source of energy for living organisms and play roles in structural support. Simple carbohydrates, such as glucose, are readily used for immediate energy, while complex carbohydrates like starch store energy for later use. Plants utilize cellulose, a complex carbohydrate, to form rigid cell walls, providing structural integrity. Carbohydrates can be classified into monosaccharides, disaccharides, and polysaccharides, depending on the number of sugar units they contain.
Lipids
Lipids are a varied group of biomolecules largely insoluble in water. They are important for long-term energy storage, providing more than twice the energy per gram compared to carbohydrates or proteins. Lipids are also key components of cell membranes, forming the barrier that separates the cell’s interior from its external environment. Examples include fats, oils, phospholipids, and steroids, with functions such as insulation, protection, and acting as chemical messengers.
Proteins
Proteins are highly diverse biomolecules made from smaller units called amino acids, linked in long chains. There are 20 types of amino acids; their specific sequence and folding determine a protein’s unique three-dimensional structure and function. Proteins perform many roles, acting as enzymes that speed up biochemical reactions, transporting molecules like oxygen, and providing structural support for cells and tissues. They also function as antibodies for immunity, regulate bodily processes as hormones, and contribute to muscle movement.
Nucleic Acids
Nucleic acids, including DNA and RNA, store and transfer genetic information. DNA carries the complete genetic instructions for an organism’s development, functioning, and reproduction. RNA plays a central role in translating these instructions into proteins, acting as an intermediary in gene expression. These molecules are polymers made of repeating monomer units called nucleotides, each consisting of a sugar, a phosphate group, and a nitrogenous base.