Remember that biomolecules build up living organisms and are also required for their growth and maintenance. They are any of the numerous substances that are produced by cells and living organisms. Biomolecules have a wide range of sizes and structures and perform a vast array of functions; thus, they are composed of different kinds of elements. These are called CHNOPS elements; the letters stand for the chemical abbreviations of Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur. There are four major classes of Biomolecules – Carbohydrates, Proteins, Nucleic acids and Lipids.
The table below shows the elements that are present in the major classes of biomolecules. [Macromolecules --- Elements Present Carbohydrates --- carbon, hydrogen and oxygen Protein --- carbon, hydrogen, oxygen, nitrogen and sulfur Lipids --- carbon, hydrogen, oxygen, phosphorus, sulfur (lipids can also contain N, but for most cases, this is sufficient) Nucleic Acid --- carbon, hydrogen, oxygen, phosphorus, nitrogen and sulfur]
Carbohydrates These molecules are comprised of the elements carbon (C), hydrogen (H), and oxygen (O). Commonly, these molecules are known as sugars. Carbohydrates can range in size from very small to very large. Like all the other biomolecules, carbohydrates are often built into long chains by stringing together smaller units. This works like adding beads to a bracelet to make it longer. The general term for a single unit or bead is a monomer. The term for a long string of monomers is a polymer. Examples of carbohydrates include the sugars found in milk (lactose) and table sugar (sucrose). Carbohydrates are chemically defined as polyhydroxy aldehydes or ketones or compounds which produce them on hydrolysis. In layman’s terms, we acknowledge carbohydrates as sugars or substances that taste sweet. They are collectively called as saccharides (Greek: sakcharon = sugar). Depending on the number of sugar units, carbohydrates can be as monosaccharides (1 sugar unit), oligosaccharides (2-10sugar units) and or polysaccharides (more than 10 sugar units).
Carbohydrates have several functions in cells. They are an excellent source of energy for the many different activities going on in our cells. Some carbohydrates may have a structural function. For example, the material that makes plants stand tall and gives wood its tough properties, is a polymer form of glucose known as cellulose. Other types of sugar polymers make up the stored forms of energy known as starch and glycogen. Starch is found in plant products such as potatoes, and glycogen is found in animals.
Proteins
Proteins are another class of indispensable biomolecules, which make up around 50 percent of the cellular dry weight. Proteins are comprised of the elements carbon, nitrogen, oxygen, hydrogen and sometimes sulfur. Proteins are polymers of amino acids, arranged in the form of chain called polypeptide. Depending on how the structure of a protein is arranged, it gives rise to a certain level of structural organization. The level can be classified as primary, secondary, tertiary and quaternary.Proteins play both structural and dynamic roles. They help form many of the structural features of the body including hair, nails and muscles. Myosin is the protein that allows movement by contraction of muscles Proteins are also present as a major component of cell membranes. Being part of cell membranes, proteins act as carriers or channels, facilitating the movement of ions and molecules in and out of the cells. Ions like sodium, potassium and chloride, molecules like glucose are maintained at proper concentration for cells to function normally. Proteins also acts as catalyst. A large group of proteins, known as enzymes, enable the cells to carry out chemical reactions fast. In order for the organism to maintain growth and survival, the food being consumed must be converted to energy at an appreciable rate.
Lipids
The term lipid refers to a wide variety of biomolecules including fats, oils, waxes and steroid hormones. Regardless of their structure, location or function in a cell/body, all lipids share common features that enable them to be grouped together. They do not dissolve in water; they are hydrophobic. The hydrophobic nature of the lipids dictates many of their uses in biological systems. Lipids are composed primarily of carbon, hydrogen, oxygen, phosphorus and sulfur (lipids also contain nitrogen in some cases). Fats are a good source of stored energy while oils and waxes are used to form protective layers on our skin, preventing infection. Some lipids, the steroid hormones, are important regulators of cell activity. The activities of steroid hormones such as estrogen have been implicated in cancers of the female reproductive system.
Nucleic Acids
Nucleic acid, naturally occurring chemical compound that is capable of being broken down to yield phosphoric acid, sugars, and a mixture of organic bases (purines and pyrimidines). Nucleic acids are the main information-carrying molecules of the cell, and, by directing the process of protein synthesis, they determine the inherited characteristics of every living thing. These molecules are comprised of elements carbon, hydrogen, oxygen, phosphorus and nitrogen. The two main classes of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
DNA is the master blueprint for life and constitutes the genetic material in all free living organisms and most viruses. DNA contains the information on what proteins will be created. On the other hand, RNA is the one responsible to create the proteins based on the information given by the DNA. RNA is the genetic material of certain viruses, but it is also found in all living cells.
Nucleic acids are polynucleotides—that is, long chainlike moleculescomposed of a series of nearly identical building blocks called nucleotides. Each nucleotide consists of a nitrogen-containing aromatic base attached to a pentose (five-carbon) sugar, which is in turn attached to a phosphate group. Each nucleic acid contains four of five possible nitrogen-containing bases: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U). A and G are categorized as purines, while C, T, and U are collectively called pyrimidines.
Biomolecules have a single basic building unit called a monomer. It comes from the Greek words monos, meaning "single" and meros meaning "part”.
A monomer is a single unit forming a long chain of molecules creating a repeated pattern. The long chain molecule is now composed of many atoms. Monomers are joined together to form polymers. The prefix “-poly” comes from the Greek word polus, meaning “many”, so polymer means "many parts." This is a long molecule consisting of many similar building blocks, or a repeated pattern of various building blocks.