Biomolecules are organic compounds produced by living organisms, serving as the fundamental building blocks of all living things. They orchestrate chemical reactions and provide the structural framework for cells and tissues.
Carbohydrates
Carbohydrates are macronutrients found in foods and drinks, encompassing sugars, starches, and fiber. They serve as a primary energy source for the body. The digestive system breaks carbohydrates down into glucose, which is then absorbed into the bloodstream. This glucose can be used immediately for fuel or stored as glycogen in the liver and muscles for later use.
Carbohydrates are categorized into simple and complex types, based on their chemical structure and digestion rate. Simple carbohydrates, like glucose and fructose, consist of one or two sugar molecules, providing rapid energy. They are found naturally in fruits and milk, and in processed sugars. Complex carbohydrates, including starches and fiber, are longer chains of sugar molecules that break down slower, offering sustained energy. Examples include whole grains, vegetables, and legumes.
Lipids
Lipids are a diverse group of organic compounds including fats, oils, waxes, and steroids, characterized by their insolubility in water. They perform various functions, such as long-term energy storage, insulation, and organ protection. Lipids offer a highly concentrated energy source, providing 9 kilocalories per gram, more than double that of carbohydrates or proteins. Excess energy from food can be stored as lipids in adipose tissue.
Beyond energy, lipids are integral components of cell membranes, helping to maintain their fluidity and flexibility while regulating what enters and exits cells. Phospholipids, for example, form the bilayer structure of cell membranes. Certain lipids, like steroid hormones such as testosterone and estrogens, act as chemical messengers, coordinating processes throughout the body. Cholesterol, another type of lipid, is necessary for absorbing fats and vitamins, and for producing hormones and bile salts for digestion.
Proteins
Proteins are large, complex molecules composed of smaller units called amino acids, which are linked together in long chains. These molecules are highly versatile and perform a wide array of functions throughout the body. Many proteins act as enzymes, accelerating nearly all of the thousands of chemical reactions that occur in cells, such as those involved in digestion. For instance, enzymes like lactase break down specific sugars, enabling nutrient absorption.
Proteins also provide structural support, forming components of tissues like muscle, hair, and skin. Collagen, a structural protein, contributes to the strength of bones and skin. Other proteins, such as hemoglobin, transport substances like oxygen throughout the body. Proteins also play a role in immunity by forming antibodies that defend against foreign invaders, and some act as hormones to transmit signals between cells and organs.
Nucleic Acids
Nucleic acids, primarily deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are macromolecules that carry genetic information. Their main function involves storing and transmitting the instructions necessary for the development, functioning, growth, and reproduction of living organisms. DNA serves as the long-term storage of genetic information, organized into chromosomes, containing instructions for building and maintaining an organism.
RNA plays a complementary role, primarily involved in expressing this genetic information. Messenger RNA (mRNA) carries genetic instructions from DNA to the ribosomes, where proteins are synthesized. Transfer RNA (tRNA) and ribosomal RNA (rRNA) also participate in protein production by bringing the correct amino acids and forming the structural component of ribosomes, respectively. While DNA is typically double-stranded and more stable for long-term storage, RNA is generally single-stranded and suited for short-term tasks in genetic information transfer.