Biomolecules in living organisms: Definition and Types

Biomolecules are referred to as the building blocks of the body. The body of complex organisms like humans is made up of trillions of cells that work together to carry out the vital functions. Biomolecules are crucial for body functioning, growth and development of the organism.

• Biomolecule is also known as a biological molecule. 
• Biomolecules come in a wide variety of shapes, sizes, and functions. 
• Carbohydrates, lipids, nucleic acids, and proteins are the four main biomolecules..
• The health of the cells and living creatures must be maintained by having a correct biomolecule composition.

Key Terms: Biomolecules, Carbohydrates, Polysaccharides, Steroids, DNA, RNA, Nucleic acids

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What are Biomolecules? 

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Biomolecules are chemical compounds produced by living creatures that come in a variety of sizes, from small molecules (metabolites) to enormous molecules (protein and carbohydrates).

• Proteins, carbohydrates, and nucleic acids make up the principal class biomolecules 
• Bio molecules are essential to carry out fundamental bodily activities, without which no creature would live.
• The first biomolecules were created by chemical evolution.
• They ranged in size from microscopic macromolecules to enormous macromolecules.
• The microscopic molecules are DNA, RNA, Lipid and Carbohydrates.
• Examples of enormous macromolecules are hormones and metabolites.
• The production of biomolecules involves carbon compounds. 
• They combine covalently to create a number of different compounds with other elements. 
• Some biomolecules are regarded as hydrocarbon derivatives.
• The hydrogen atoms in them are swapped out for functional groups including alcohols, amines, aldehydes, ketones, and carboxylic groups.

Also Read: Difference Between Nucleotide and Nucleoside

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Types of Biomolecules

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Biomolecules that are the building blocks of most higher organisms include the below types.

1. Carbohydrates

A healthy diet must include carbohydrates. They offer the necessary energy for carrying out work. It is classified as a polyhydroxy aldehyde and polyhydroxy ketone. The most prevalent type of biomolecule on the planet is a carbohydrate.

Carbohydrates can be of three types.

a. Monosaccharides

The simplest carbohydrates are monosaccharides, which are also known as simple sugars. The typical chemical formula of simple sugar is (CH₂O)x. Glucose and fructose are two typical examples of simple sugars or monosaccharides. Since each of these monosaccharides have six carbons, they are referred to as hexoses.

b. Disaccharides

Disaccharides are hydrolyzed to produce two molecules of either the same or different monosaccharides. The two monosaccharide units are connected by a glycosidic linkage. This linkage is an oxide bond created by the loss of a water molecule. One of the most prevalent disaccharides, sucrose hydrolyze to glucose and fructose. Other crucial disaccharides include maltose and lactose (often referred to as milk sugar).

c. Polysaccharides

Long monosaccharide units are linked by a glycosidic bond to form polysaccharides. The common example of polysaccharide is starch. It is the primary carbohydrate that plants use for storage. It is made up of two parts, Amylose and Amylopectin, and is a polymer of glucose. Cellulose is another example of polysaccharides that is mostly present in plants.

2. Proteins

Amino acid residues form unbranched polymers called proteins. There are roughly 22 amino acids used in the production of proteins. Proteins are divided into four classes based on how they are structurally organized.

a. Primary structure

It is created when two amino acids form a peptide bond.

b. Secondary structure

The hydrogen bonds between the amide hydrogen and the carbonyl oxygen of the peptide backbone cause a folded shape to form the polypeptide. Alpha- and beta-sheet structures are found in the secondary structure of protein.

c. Tertiary structure

The interaction between the R-groups or side chains of the amino acids results in the creation of three-dimensional conformation. Hydrophobic, electrostatic, hydrogen, and van der Waals forces of interaction are the main bonds that help to build this structure.

d. Quaternary structure

The quaternary structure develops between two or more polypeptide chains. A subunit of this structure is a single polypeptide chain. The quaternary structures may be found between two polypeptide chains that are the same or different. These structures are formed via hydrophobic, electrostatic, hydrogen, and covalent cross-links.

3. Nucleic acid

Nucleic acid serves as a genetic material in all organisms. Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are the two natural forms of nucleic acids. Nucleotides form nucleic acids by joining together and forming a long chain. Nucleotide is a subunit made up of three pieces. The three components of the nucleotide are a phosphate group, a 5-carbon sugar, and a nitrogen base. 

a. DNA (Deoxyribonucleic acids)

Genetic information is stored and coded in the body via DNA. The structure of DNA allows inheritance of genetic information in children from parents. 

• The DNA nucleotides have adenine, thymine, guanine, and cytosine as a nitrogen base. 
• They can only pair with one another in specific sequences. 
• Adenine pairs with thymine and guanine pairs with cytosine. 
• Two polynucleotides of DNA are coiled around a core helix to form the double helical structure. 
• The  two antiparallel strands with complementary base pairs are connected by hydrogen bonding. 

b. RNA (Ribonucleic acids)

RNA is crucial for the production of proteins because it carries out the translation. RNA translates the information that is made by codons. There are mainly 3 types of RNA- messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA). Apart from that, RNA is a genetic material for some viruses.

The following are a few tasks that RNA performs.

• DNA to protein translation
• Facilitating communication between ribosomes and DNA
• Aids ribosomes in selecting the appropriate amino acids to produce new proteins in the body.

4. Lipids 

Organic molecules known as lipids are soluble in organic solvents like ether, benzene, or chloroform (like dissolves like), but they are insoluble or only moderately soluble in water.

They contain a chain of hydrocarbons and are hydrophobic in nature. They are largely engaged in membrane structure and energy storage. Lipids are chemically more diversified than other biomolecules. Below are the six main classes of lipids.

a. Fatty acids

Fatty acids are carboxylic acids, also known as organic acids, or long aliphatic tails (long chains). It can be saturated or unsaturated in nature. They are made up of 4-36 carbon, hydrocarbon chains and one acidic group. They may have branching or linear structure. Fatty acids can serve as the foundation for other lipid subtypes.

b. Phospholipid

These are made up of phosphate, an alcohol connected to phosphate, and fatty acids. They are a component of the organisms' cell membrane.

c. Glycolipids

These lipids have saccharide groups in them. They participate in signal transduction and are parts of the cell membrane.

d. Waxes

These are fatty acid and long-chain alcohol esters. Hydrocarbon chains of 14–36 carbons make up their structure. Numerous animals and plants can synthesize waxes. Bee wax, which is made up of an ester of triacontanol alcohol and palmitic acid, is the most well-known example of wax.

e. Steroids

Steroids are triterpene derivatives. For instance, cholesterol functions as a precursor for the manufacture of bile acids and steroid hormones. It is a component of the cell membrane as well.

f. Eicosanoids

Eicosanoids are made up of the 20 carbons of polyunsaturated fatty acids. Eicosanoids are lipid based signaling molecules that play an important role in innate immunity. They have several functions in the body. Some examples of eicosanoids and their functions are mentioned below.

• Leukotrienes mediate the Inflammation and chemotaxis.
• Thromboxanes are also eicosanoids that operate as vasoconstrictors.
• Prostaglandins induce uterus contraction and reduce blood pressure.

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Things to Remember

• Biomolecules are essential to life because they help organisms to develop, endure, and procreate. 
• Biochemistry is the branch that deals with the study of biomolecules.
• Polyhydroxy aldehyde or ketone molecules make up carbohydrates.
• Carbohydrates are categorized as monosaccharides, disaccharides, or polysaccharides.
• The earliest biomolecules were created through chemical evolution.
• Polymers of nucleotides make up nucleic acids. 
• There are two different types of nucleic acid- DNA and RNA. 
• They serve as a genetic material in all the organisms..
• Metabolites and natural products are additional biomolecules. 

Also Read: Difference Between DNA and RNA