CBSE Class 11 Biology - What is Biomolecules and Its Classes?

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CBSE Class 11 Biology Notes- Biomolecules and Its
Classes
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CBSE Class 11 Biology Notes- Biomolecules and Its
Classes

• Biomolecules are the molecules (macromolecules)
  that are synthesized in living organisms.
  Proteins, carbohydrates, lipids and nucleic acids
  are biomolecules found in all living beings.
  Small molecules like primary and secondary
  metabolites and natural products are also
  biomolecules. Carbon and hydrogen along with
  nitrogen, oxygen, sulphur, and phosphorus are
  essential constituents of all types of
  Biomolecules. The various atoms are covalently
  bonded in these biomolecules.
• There are four major classes of biomolecules
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

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CBSE Class 11 Biology Notes- Biomolecules and Its
Classes
 CARBOHYDRATES Carbohydrates are long chains of
sugars. They are a good source of energy.
A carbohydrate is a hydrocarbon molecule that
consists of carbon, hydrogen and oxygen atoms,
usually with a hydrogenoxygen atom ratio of 21.
Carbohydrates are further classified
as Monosaccharides They are simple sugars that
are composed of 3-7 carbon atoms. They have a
free aldehyde or ketone group hence they act as
reducing agents and are known as reducing
sugars. Glucose, fructose and Galactose are
monosaccharides. Disaccharides They are made of
two monosaccharides units. The bond between two
monosaccharide units is called as the glycosidic
bonds. Monosaccharides and disaccharides are
sweet in taste and crystalline and water-soluble
substances. Sucrose, Maltose, Lactose are some
disaccharides. Polysaccharides They are polymers
of monosaccharides. They are not sweet, but
complex carbohydrates. They are insoluble in
water and are not in crystalline form. Starch,
Cellulose are some polysaccharides.

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CBSE Class 11 Biology Notes- Biomolecules and Its
Classes

• LIPIDS
• Lipids are composed of long chains of fatty
  acids, they are esters of fatty acids. Fatty
  acids can be unsaturated and saturated
  hydrocarbons. A lipid is a chemical substance
  that is insoluble in water but soluble in organic
  solvents like alcohol, ether etc. Lipids are an
  important component of living cells. Lipids store
  a large amount of energy. and are constituent of
  biological membranes. Lipids have a polar head
  and non-polar tail. Lipids are part of biological
  membranes and are of three types based on the
  type of hydrophilic head present
• Glycolipids are lipids whose head region contains
  oligosaccharide (1- 15) residues.

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CBSE Class 11 Biology Notes- Biomolecules and Its
Classes

• Phospholipids contain a positively charged head
  which is attached to the negatively charged
  phosphate groups.
• Sterols head region contains a steroid ring.
  Example steroid.

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CBSE Class 11 Biology Notes- Biomolecules and Its
Classes

• PROTEINS
• Proteins are polymers of amino acids. They are
  large molecules that our cells need to function
  properly. The structure and function of the
  living organisms depend on proteins. The
  regulation of the bodys cells, tissues, and
  organs are dependent on the proteins. Amino acids
  are linked together by the peptide bond which is
  formed in between the carboxyl group and amino
  group of successive amino acids. Proteins are
  formed from 20 different amino acids.
• There are four levels of protein structure
  depending on the number of amino acids and their
  sequence.
• Primary structure of proteinThis is a linear
  structure of amino acids that are arranged in a
  particular sequence (polypeptide chain). They are
  non-functional proteins.

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CBSE Class 11 Biology Notes- Biomolecules and Its
Classes
The secondary structure of protein  The long
chain of the polypeptide is folded and arranged
in a helix shape, where the amino acids interact
by the formation of hydrogen bonds. This
structure is called the pleated sheet. Example
silk fibres. The tertiary structure of
proteinThe secondary structure of proteins is
stabilized by folding and coiling, by the
formation of ionic or hydrophobic bonds
or disulphide bridges, this results in the
formation of the tertiary structure of the
protein. Quaternary structure of protein The
protein structure consists of an assembly of more
than one polypeptide of its own, it is said to be
the quaternary structure of the protein.
 Example Haemoglobin, insulin. NUCLEIC
ACIDS Nucleic acids are organic compounds with
heterocyclic rings. They are the polymer of
nucleotides. A Nucleotide has three parts a
nitrogenous base, a pentose sugar and a phosphate
group. A nucleoside is made of the nitrogenous
base attached to a pentose sugar. The nitrogenous
bases are adenine, guanine, thiamine, cytosine
and uracil. Polymerized nucleotides form DNA/ RNA
which are genetic material of every living cell.
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CBSE Class 11 Biology Notes- Biomolecules and Its
Classes

• FUNCTIONS OF BIOMOLECULES
• Carbohydrates are the instant source of fuel and
  energy, it aids in proper functioning of our
  brain, heart and nervous, digestive and immune
  system. Deficiency of carbohydrates in the diet
  leads to fatigue, poor mental function.
• Every protein in the body has specific functions,
  some proteins provide structural support, help in
  body movement, and also defence against germs and
  infections.
• Proteins Lipids are the storage form of energy.
  Structure of membranes are composed of lipids
  which forms a barrier and controls the flow of
  material in and out of the cell. Lipid hormones,
  like sterols, help in providing communication
  between cells.
• Nucleic Acids (DNA and RNA), carry genetic
  information in the cell. They also help in
  protein synthesis, by the process of translation
  and transcription.

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CBSE Class 11 Biology Notes- Biomolecules and Its
Classes

• For more topics of class 11 biology, click here
• Viruses
• Absorption and Assimilation of Proteins
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