The document discusses the structure and functions of nucleic acids and proteins. It describes the four levels of structure for both - primary, secondary, tertiary, and quaternary. For nucleic acids, this includes the nucleotide components, base pairing, and interactions with other molecules. For proteins, it includes the amino acid sequence, folding patterns like alpha helices and beta sheets, and bonding interactions that give shape. Nucleic acids function to store and transmit genetic information and direct protein synthesis. Proteins function in roles like repair, energy, movement, catalysis, transport, and structure.

3. 1) Structure Of Nucleic Acids
2) Functions Of Nucleic Acids
3) Structure Of Proteins
4) Functions Of Proteins

5. Introduction
 It refers to the Nucleic Acids Like DNA & RNA.
 It is divided into 4 levels:
 Primary
 Secondary
 Tertiary
 Quaternary

6. Primary structure
 It is a linear sequence of nucleotides that are linked together by
Phosphodiester bonds.
 It makes Primary structure of DNA or RNA.
 Nucleotides consist of 3 components:
 Nitrogenous base;
 Adenine
 Guanine
 Cytosine
 Thymine ( DNA only )
 Uracil ( RNA only )
 5-carbon sugar which is called Deoxyribose (found in DNA)
and Ribose (found in RNA).
 One or more phosphate groups.
 The nitrogen bases Adenine and Guanine are Purine in structure .
 Cytosine, Thymine and Uracil are Pyrimidine in Structure.

7. Secondary structure
 It is the set of interactions between bases.
 In DNA double helix, the two strands of DNA are held together by H- Bonds.
 It is responsible for the shape that the nucleic acid assumes.
 Purines consist of a Double Ring Structure.
 Pyrimidines has a Single Ringed Structure.
 A Purine base always pairs with a pyrimidine base (Guanosine (G) pairs with
Cytosine(C) and Adenine(A) pairs with Thymine (T) or Uracil (U)).
 DNA's secondary structure is predominantly determined by Base Pairing of the two
Polynucleotide Strands wrapped around each other to form a Double Helix.
 In RNA, Secondary Structure consists of a Single Polynucleotide.
 The Antiparallel Strands form a Helical Shape.
 The 4 basic elements in the secondary structure of RNA are;
 Helices
 Loops
 Bulges
 Junctions.

8. Tertiary structure
 It is the locations of the atoms in 3D space.
 Large-scale folding in a linear polymer occurs and the entire chain is folded into a specific 3D
shape.
 There are 4 areas in which the structural forms of DNA can differ.
 Handedness - right or left
 Length of the helix turn
 Number of base pairs per turn
 Difference in size between the major and minor grooves
 The tertiary arrangement of DNA's Double Helix in space includes;
 B- DNA
 A-DNA
 Z-DNA
 B-DNA is the most common form of DNA and it is a more narrow, elongated helix than A-DNA. Its
wide major groove makes it more accessible to proteins.
 A-DNA is a form of the DNA duplex observed under dehydrating conditions. It is shorter and wider
than B-DNA. RNA adopts this double helical form, and RNA-DNA duplexes are mostly A-form.
 Z-DNA is a relatively rare left-handed double-helix. Its function is unclear. It has a more narrow,
more elongated helix than A or B.

9. Quaternary structure
 It refers to a higher-level of organization of nucleic acids(interactions
of the nucleic acids with other molecules).
 The most commonly seen form is Chromatin which leads to its
interactions with the Histone Proteins.
 It is also refers to the interactions between separate RNA units in
Ribosome.

10. Functions of Nucleic Acids
 DNA: Transmission of Hereditary Characters.
 Store house of genetic information control protein
synthesis in cell.
 Direct synthesis of RNA.
 RNA: Direct synthesis of Specific Proteins.
 m-RNA takes genetic message from RNA.
 t-RNA transfers activated amino acid, to the site of
protein synthesis.
 r-RNA are mostly present in the ribosomes, and
responsible for stability of m-RNA.

12. Introduction
 It is the 3D arrangement of atoms in a Protein Molecule.
 Proteins are polypeptides made from sequences of monomer
amino acids.
 Proteins fold into one or more specific spatial conformations
driven by a number of Non-Covalent interactions such as H-
Bonding, Ionic Interactions, Van Der Waal Forces,
and Hydrophobic packing.
 Protein structures range in size from tens to several thousand
amino acids.
 A protein may undergo reversible structural changes in
performing its biological function.
 The alternative structures of the same protein are referred to
as different conformations.

13. Primary Structure
 It refers to the linear sequence of
amino acids in the polypeptide chain.
 It is held together by Covalent Bonds
like Peptide Bonds.
 The 2 ends of the Polypeptide Chain are referred to
as the Carboxyl Terminus (C-terminus) and the
Amino Terminus(N-terminus).
 It is determined by the Gene corresponding to the
Protein.

14. Secondary Structure
 It refers to highly regular local sub-structures on the actual
polypeptide backbone chain.
 There are 3 main types of Secondary Structures;
 Alpha Helix
 Triple Helix
 Beta Pleated Sheet
 The Alpha Helix is a right-handed coiled strand. The stability
to the structure is given by H-bonding.
 The Triple Helix is 3 polypeptide chains woven together. H -
bonding between –OH groups gives a strong structure.
 The Beta –Pleated Sheet is created by inter-strand H-
Bonding. It is more stable due to the well-aligned hydrogen
bonds.

15. Tertiary Structure
 It is the overall 3D shape of an entire protein
molecule.
 The alpha-helixes and beta pleated-sheets
are folded into a compact Globular Structure.
 There are;
 Disulphide Bonds - A strong double bond (S=S) is formed
between the Sulphur atoms within the Cysteine monomers.
 Ionic Bonds - If 2 oppositely charged 'R' groups (+ve and -
ve) are found close to each other, and ionic bond forms
between them.
 Hydrogen Bonds - Typical H-bonds.
 Hydrophobic and Hydrophilic Interactions - Some
amino acids may be hydrophobic while others are
hydrophilic.

16. Quaternary Structure
 It is the Complete 3-D structure of a protein with
multiple peptides or proteins.
 It is stabilized by a variety of bonding interactions
including H-bonding, Salt bridges, and Disulfide
bonds which holds the various chains into a
particular geometry.

17. Functions Of Proteins
 Repair and Maintenance - Protein is termed the building block of the body.
 Energy - Protein is a major source of energy.
 Antibodies - They are specialized proteins involved in defending the body
from antigens (foreign invaders).
 Contractile Proteins - They are responsible for movement. Examples
include actin and myosin.
 Enzymes -They are proteins that facilitate biochemical reactions. They are
often referred to as catalysts because they speed up chemical reactions.
 Hormonal Proteins - They are messenger proteins which help to
coordinate certain bodily activities. Examples include insulin, oxytocin etc.
 Structural Proteins - They are fibrous and stringy and provide support.
Examples include keratin, collagen, and elastin.
 Storage Proteins - It Store Amino Acids. Examples include casein, ferritin.
 Transport Proteins - They are carrier proteins which move molecules from
one place to another around the body. Examples include hemoglobin and
Cytochromes.

18. Summary
 Nucleic Acid structure refers to the Nucleic Acids Like DNA & RNA.
 It is divided into 4 levels.
 Nucleic Acids Useful in Transmission of hereditary Characters, Direct
synthesis of specific proteins etc.
 Protein Structure is the 3D arrangement of atoms in a Protein
Molecule.
 It is divided into 4 Structures.
 It has H-Bonding, Ionic Interactions, Van Der Waal Forces etc.
 Proteins Helps for Repair and Maintenance, Energy etc.

19. References
 Websites
 healthyeating.sfgate.com
 biology.about.com
 nutristrategy.com
 sophia.org
 Journals
 Proteins: Structure, Function, and Bioinformatics(ISI
Journal Citation Reports © Ranking: 2014: 37/73 (Biophysics);
148/290 (Biochemistry & Molecular Biology))
 Nucleic Acids – Chemistry and Applications (J. Org.
Chem., 2013.Copyright © 2013 American Chemical Society)

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