Biomolecules:

Biomolecules are the molecules that are found in living organisms and are
crucial for the structure and function of cells and organs. These molecules
include carbohydrates, proteins, lipids, and nucleic acids. These molecules are
involved in a variety of essential biological processes, such as providing energy,
building cell structures, storing genetic information, and catalyzing biochemical
reactions.

1. Carbohydrates:
Carbohydrates are organic compounds made of carbon, hydrogen, and oxygen.
They serve as the primary energy source for the body.
Types of Carbohydrates:
 Monosaccharides: These are the simplest form of carbohydrates.
Examples include glucose, fructose, and galactose. They are the basic
building blocks of other carbohydrates.
o Glucose: A six-carbon sugar (C6H12O6) that is an important
energy source for cells.
o Fructose: A sugar found in fruits and honey.
 Disaccharides: Formed by the combination of two monosaccharides.
Examples include:
o Sucrose (table sugar): Composed of glucose and fructose.
o Lactose (milk sugar): Composed of glucose and galactose.
 Polysaccharides: These are long chains of monosaccharides. Examples
include:
o Starch: A storage form of glucose in plants.
o Glycogen: A storage form of glucose in animals.
o Cellulose: A structural polysaccharide found in plant cell walls.
Functions of Carbohydrates:
 Energy Source: Glucose is the primary energy source for the body.
 Energy Storage: Starch in plants and glycogen in animals store energy.
  Structural Component: Cellulose provides structural support in plant
cells.

2. Proteins:
Proteins are large molecules made up of amino acids. They play a vital role in
almost every biological process, such as catalyzing reactions (enzymes),
providing structural support, and transporting substances.
Structure of Proteins:
 Amino Acids: Proteins are made up of 20 different amino acids. The
sequence and arrangement of amino acids determine the structure and
function of the protein.
o Primary structure: The linear sequence of amino acids.
o Secondary structure: The folding of the amino acid chain into
structures like alpha helices and beta-pleated sheets.
o Tertiary structure: The three-dimensional shape of the protein.
o Quaternary structure: The arrangement of multiple protein
subunits.
Functions of Proteins:
 Enzymes: Proteins that speed up chemical reactions (e.g., amylase
breaks down starch).
 Structural Proteins: Provide structural support (e.g., collagen in
connective tissues, keratin in hair).
 Transport Proteins: Carry molecules across membranes or through the
bloodstream (e.g., hemoglobin carries oxygen in blood).
 Hormones: Some proteins act as hormones (e.g., insulin regulates blood
sugar levels).

3. Lipids:
Lipids are a diverse group of hydrophobic molecules that are important for
energy storage, insulation, and making up cell membranes.
Types of Lipids:
 Fats and Oils: These are used for long-term energy storage. Fats are solid
at room temperature (e.g., butter), while oils are liquid (e.g., olive oil).
 Phospholipids: These form the structure of cell membranes. They have
hydrophobic tails and hydrophilic heads, which help create a barrier that
controls the movement of substances into and out of cells.
 Steroids: A type of lipid that includes cholesterol and hormones like
testosterone and estrogen.
Functions of Lipids:
 Energy Storage: Lipids store energy efficiently, providing more energy
per gram than carbohydrates.
 Insulation: Lipids help to insulate organs and maintain body
temperature.
 Cell Membrane: Phospholipids make up the bilayer of cell membranes,
controlling what enters and exits the cell.
 Hormones: Steroids act as hormones that regulate various physiological
processes.

4. Nucleic Acids:
Nucleic acids are biomolecules that store and transmit genetic information.
There are two types of nucleic acids: DNA (Deoxyribonucleic Acid) and RNA
(Ribonucleic Acid).
DNA (Deoxyribonucleic Acid):
 DNA carries the genetic blueprint for the development and functioning
of living organisms.
 Structure: DNA consists of two strands that form a double helix. The
strands are made up of nucleotides, which include:
o A sugar (deoxyribose),
o A phosphate group,
o A nitrogenous base (adenine, thymine, cytosine, and guanine).
RNA (Ribonucleic Acid):
 RNA is involved in protein synthesis. It is a single-stranded molecule that
is transcribed from DNA and then used to synthesize proteins.
 Types of RNA:
o mRNA (messenger RNA): Carries the genetic code from DNA to
the ribosomes for protein synthesis.
o tRNA (transfer RNA): Brings amino acids to the ribosome during
protein synthesis.
o rRNA (ribosomal RNA): Forms part of the ribosome, where
protein synthesis occurs.
Functions of Nucleic Acids:
 Genetic Information: DNA stores and transmits genetic information from
one generation to the next.
 Protein Synthesis: RNA plays a crucial role in the synthesis of proteins,
following the instructions in DNA.

5. Enzymes:
Enzymes are proteins that act as biological catalysts. They speed up chemical
reactions in the body without being consumed in the process.
Properties of Enzymes:
 Specificity: Each enzyme catalyzes only one specific type of reaction.
 Active Site: The region of the enzyme where the substrate binds and
undergoes a chemical reaction.
 Cofactors: Some enzymes require non-protein molecules (like vitamins
or metal ions) to function properly.
Functions of Enzymes:
 Speeding Up Reactions: Enzymes lower the activation energy needed for
reactions to take place.
  Regulation: Enzymes regulate the biochemical pathways in the body,
ensuring that reactions occur in the correct sequence and at the right
rate.

Summary of Functions of Biomolecules:

 Carbohydrates: Provide energy and structural support.
 Proteins: Build and repair tissues, catalyze reactions, transport
molecules, and regulate bodily functions.
 Lipids: Store energy, insulate the body, form cell membranes, and act as
signaling molecules.
 Nucleic Acids: Store and transfer genetic information, and are involved in
protein synthesis.

Conclusion:
Biomolecules are the fundamental building blocks of life. They play essential
roles in all living organisms, from providing energy to catalyzing reactions and
storing genetic information. Understanding biomolecules and their functions is
crucial in the study of biology and essential for the Class 12 Chemistry and
Biology curriculum. This knowledge forms the foundation for understanding
various physiological processes and the biochemistry of life.