Biomolecules

Biomolecules are crucial organic compounds vital for the maintenance and metabolic functions of living organisms. Serving as the backbone of life’s sustenance, these molecules range from smaller entities like primary and secondary metabolites and hormones, to larger macromolecules such as proteins, nucleic acids, carbohydrates, and lipids.

Now, let’s delve into their significance.

Also, read – Biomolecules in Living Organisms

There are four major classes of Biomolecules –  Carbohydrates, Proteins, Nucleic acids and Lipids. Each of them is discussed below.

Carbohydrates are scientifically described as polyhydroxy aldehydes or ketones, or substances that yield them upon hydrolysis. In simpler terms, we recognize carbohydrates as sugars or compounds with a sweet taste. They are collectively referred to as saccharides (from the Greek word “sakcharon” meaning sugar). Based on the number of sugar units obtained upon hydrolysis, they are categorized as monosaccharides (1 unit), oligosaccharides (2-10 units), and polysaccharides (more than 10 units). Carbohydrates serve various functions; they are the primary source of dietary energy and are crucial as a structural component in many living organisms—for instance, cellulose plays a significant role as a structural fiber in plants.

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Proteins constitute another essential class of biomolecules, comprising approximately 50 percent of the cellular dry weight. Proteins are polymers of amino acids arranged in the form of polypeptide chains. Proteins exhibit a hierarchical structure, classified into primary, secondary, tertiary, and in some cases, quaternary structures. This classification is based on the complexity of the folding pattern of a polypeptide chain. Proteins fulfill both structural and dynamic roles in organisms. For instance, myosin, a protein, facilitates movement through the contraction of muscles, while the majority of enzymes are protein-based and catalyze biochemical reactions.

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Nucleic acids are essential genetic materials found within cells, carrying hereditary information from parents to offspring. There are two primary types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Their main function involves the transfer of genetic information and the synthesis of proteins through processes known as translation and transcription. The basic building block of nucleic acids is the nucleotide, composed of a nitrogenous base, a pentose sugar, and a phosphate group. Nucleotides are connected by 3′ and 5′ phosphodiester bonds. The specific nitrogenous base attached to the pentose sugar distinguishes one nucleotide from another. DNA contains four major nitrogenous bases: adenine, guanine, cytosine, and thymine. In RNA, thymine is replaced by uracil. The structure of DNA is often described as a double helix, formed by hydrogen bonding between the bases of two antiparallel polynucleotide chains. Overall, the DNA structure resembles a twisted ladder.

Explore more- Difference Between DNA and RNA

Lipids are organic compounds that are insoluble in water yet soluble in organic solvents. They are closely related to fatty acids and are essential for the functioning of living cells. Lipids encompass a variety of substances such as fats, waxes, sterols, fat-soluble vitamins, mono-, di-, or triglycerides, phospholipids, and more. Unlike carbohydrates, proteins, and nucleic acids, lipids are not considered polymeric molecules. They play a vital role in cellular structure and serve as a primary source of energy.

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