Any living matter comprises six elements (Carbon, oxygen, Nitrogen, Sulphur, Phosphorous, and Hydrogen). In humans, they form about 90% of the dry weight.

Biomolecules are produced by living organisms and are very important for their day-to-day activities. They are structurally dependent and lose their function on disruption. They are usually composed of simple subunits called monomers, which combine chemically to form large and complex polymers.

Carbon, Hydrogen, and Oxygen are the common elements that make all biomolecules.

Biomolecules are broadly classified into four categories, carbohydrates, proteins, lipids, and nucleic acids. To solve biology assignments, you need to know these topics.

1. Carbohydrates

These are made up of carbon, hydrogen, and oxygen.

Carbohydrates are made up of building blocks like sugars, fiber, and starches. Sugars are usually found in vegetables, milk, and fruits, whereas fiber and starches are generally found in legumes and grains.

These sugars are named saccharides and are classified into monosaccharides, disaccharides, and polysaccharides based on the presence of one or two or more sugar residues. These sugars are the best energy reservoirs for breaking down into simple sugars called glucose.

Examples:

– Monosaccharides: Glucose, fructose, and Galactose.

– Polysaccharides: Sucrose (made up of glucose and fructose saccharides).

Functions of Carbohydrates:

– Carbohydrates are the best energy reservoirs

–  They are the form precursors for most organic compounds.

– They form the vital part of the backbone of DNA & RNA.

– Glycoproteins & glycolipids form a significant part of the cell membrane and aid in cellular functions like growth and adhesion.

– Plants store the sugars as starch, whereas animals store them as glycogen.

2. Proteins

These are the predominantly found biomolecules in the living system. They are found in every cell and form 50% of the dry weight. They include the structural and physiological basis of life.

Proteins are made up of amino acids. Hundreds of amino acids exist in nature, but only 20 amino acids are involved in building the proteins. Each amino acid contains an amino group at one end and a carboxy group at the other, with a central carbon atom. The side chain, which is variable like hydrophobic, hydrophilic, charged, and neutral, makes the different proteins differ.

Soya products and animal sources (meat, poultry, fish, and eggs) are rich in proteins. Amino acids peptide bonds link the building blocks of proteins. Ribosomes, a cell organelle, help form peptide bonds between these amino acids and help form polypeptide chains, which, on conformational changes, develop into proteins. The proteins consumed are generally broken down into their amino acids, which are now feasible to enter the blood circulation. In due course of circulation, these amino acids are later used to build proteins.  

Functions of Proteins

Proteins serve structurally and dynamically.

– They are solely responsible for giving structure and strength to the body.

– They are found in elastin and collagen, which form the most complex matrix in the body.

– They are also crucial in giving structure and flexibility to the epidermal tissues.

– They aid in regulating genetic functions.

– They help in muscle contraction via muscle proteins.

– Enzymes, clotting factors, hormones, and antibodies receptors are all made up of proteins and play a crucial role in the body's metabolism.

– They help in communicating between and within the cells

– As such, they are often credited as working horses of the cell.

3. Lipids:

These are the diverse group of biomolecules that are hydrophobic and form the structural components of the cell membranes, and they are similar to carbohydrates in terms of storage.

They are hydrophobic as such, do not dissolve in water. They are in great demand by the body as they form the chief storage form of energy. Plant lipids are generally liquids (e.g., olive oil), whereas animal lipids are solids (fats). The building blocks of Fats are usually made up of fatty acids and glycerol. Fatty acids are typically used for storing energy. These link together with the glycerol subunits to form the diglycerides and triglycerides.

Examples of fatty acids are lauric, oleic, palmitic, stearic, linoleic, and linolenic.

Functions of Lipids:

– They are the form of concentrated energy reserves for the body.

– Lipids are the main components in the structure of cell membranes.

– These aid in regulating membrane permeability.  

– They are a rich source of fat-soluble vitamins like A, D, E, and K.

– These act as metabolic regulators via steroids and prostaglandins).

4. Nucleic Acids

These complex biomolecule groups form life's main and essential components.

These are the most critical macromolecules in encoding, transmitting, and gene expression. Genetic information is usually encrypted in the form of nucleic acids and is sent to the next generations. They also help in protein synthesis.

They are made up of simple subunits called nucleotides. These subunits comprise carbon sugar, a phosphate group, and a base. Based on the sugar moiety present, they are further classified as DNA and RNA. In the case of DNA, the sugar moiety is the deoxyribose sugar, and in the case of RNA, it is ribose sugar.

DNA, in turn, is composed of four nucleotides called guanine (G), adenine(A), thymine(T), and cytosine(C). In the case of RNA, uracil (U) replaces thymine. Two DNA strands are joined together by weak hydrogen bonds between the bases. RNA is usually a single strand and does not involve in the double helix formation.

Functions of Nucleic Acids:

– They aid in storing and transferring genetic information. 

– They help in protein synthesis. 

– They regulate the cell cycle and control RNA synthesis. 

– m-RNA helps in transferring the genetic message from RNA.

– rRNA, primarily seen in the ribosomes, give stability to mRNA.