The document discusses the structure and function of proteins, starting with the basic definition of proteins and amino acids. It outlines the four levels of protein structure (primary, secondary, tertiary, quaternary) and explains the connection between their structure and functions, which include support, transport, signaling, movement, defense, catalysis, and hormonal regulation. It also describes the process of protein biosynthesis and the difference between proteins and polypeptides.

1. Protein structure and
function
Name: Rohama
Roll no : 24
BS(4th)

2. Outline
• What is protein ?
• Amino acids structure
• How amino acids are linked
• How proteins fold and unfold
• Levels of protein structure
• Relationship between protein structure and function
• The functions of proteins

3. Protein
• Important biological molecule
• Protein/polypeptide is a polymer
• Monomers amino acids
• Basic 20 amino acids
A.a A.a A.a A.a A.a
monomer
Polymer(polypeptide)

4. Amino acids
 Amine group
 Carboxyl group
 Functional group
Different variable groups
Gives different properties to
amino acids

5. Different amino acids

6. Amino acids linkage
Condensation
reaction
>or= 3 amino
acids make
protein

7. Biosynthesis
DNA
GENES
mRNA
protein
Transcription
Translation

8. Levels of protein structure
 4 levels of protein structure
 Based on chemical linkages
1. Primary structure
2. Secondary structure
3. Tertiary structure
4. Quaternary structure

9. Primary structure
Refers to the sequence or order of amino acids
Bonding
 covalently linked by peptide bonds
 Each amino acid is “residue”

10. Secondary structure
Localized arrangement of adjacent amino acids formed as polypeptide
chain folds
 Two main types of secondary structure
 α-helix and the β-strand or β-sheets
bonding
hydrogen bonding

12. Tertiary structure
• Tertiary structure refers to the three-dimensional structure of
monomeric and multimeric protein molecules
• Bondings
hydrogen bonding
ionic bonding
Van der walls interactions
disulfide linkage

14. Quaternary structure
• Quaternary structure is the three-dimensional structure
• Consist of the aggregation of two or more individual polypeptide
chains (subunits)
• They operate as a single functional unit.
dimers trimers
multimers

15. Quaternary structure

16. Functions of protein
• Structural support
• Transporting molecules
• Receiving and sending signals
• Movement
• Defense against diseases
• Catalysis of biochemical reactions
• Hormonal proteins

17. Functions

18. Distribution according to functions

19. Difference between protein and polypeptide