Proteins are macromolecules composed of one or more chains of amino acids. There are 20 amino acids that are the building blocks of proteins. Amino acids join together via peptide bonds to form polypeptides or proteins. Proteins have four levels of structure - primary, secondary, tertiary, and quaternary structure. The primary structure is the linear sequence of amino acids. The secondary structure involves hydrogen bonding that forms alpha helices or beta pleated sheets. Tertiary structure is the three-dimensional shape formed by interactions between amino acid side chains. Quaternary structure results from the aggregation of multiple polypeptide subunits.

2. PROTEINS

3. PROTEIN
- First coined by Jons Jakob
Berzelius
- Comes from the Greek word
“proteios” which means “first” or
“primary”
- A macromolecule composed of one
or more polypeptide chains
- Polymers of amino acids

4. Amino Acids
- Building blocks of proteins
- 20 amino acids
- A compound that contains one
amino group (-NH2) and at least one
carboxyl group (-COOH)
- Join together by a peptide bond
- Two amino acids – dipeptide
- Many amino acids - polypeptide

5. Amino Acids
N
H2
O
–
O
SH
Cysteine
O
–
N
H2
O
CH3
Alanine
N-terminus
C-terminus

6. Tetrapeptide
NH
NH
NH
OH
N
H2
O
O
O
O
S
H
CH3
C
H3
CH3
CH3
C
H3
C A L L
Peptide bonds

7. Essential Amino Acids
-Amino acids that cannot be
synthesized by our body
-Must be provided through the
diet.k

8. Non-Essential Amino Acids
-Amino acids that can be
synthesized by our body
-Must be provided through the
diet

9. Amino Acids

10. A
m
i
n
o
A
c
i
d
s

11. Heme Oxygen
Carbon
Monoxide Histidine

13. What are the
Functions of
Proteins?

14. Functions of Proteins

15. Functions of Proteins

16. Four Levels of
Protein
Structures

17. Primary Structure
-Linear chains of amino acids

18. Secondary Structure
-Regions stabilized by hydrogen bonds
between atoms of the polypeptide backbone
-Result of hydrogen bonds between the
repeating constituents of the polypeptide
backbone.

19. Secondary Structure
Alpha (α) helix
-A delicate coil held together by
hydrogen bonding between every
fourth amino acids.

20. Secondary Structure
Beta (β) pleated sheet
-Two or more segments of the
polypeptide chain lying side by
side are connected by hydrogen
bonds between parts of the two
parallel segments
-Makes up the core of many
globular proteins

21. Secondary Structure

22. Tertiary Structure
-Three-dimensional shape stabilized by
interactions between side chains
-the overall shape of a polypeptide
resulting from interactions between
the side chains of the various amino
acids.
- hydrophobic interaction
- Disulfide bridges

23. Tertiary
Structure

24. Quaternary Structure
-The overall protein structure that
results from the aggregation of these
polypeptide subunits

25. Quaternary Structure
α subunit
β subunit

27. Did you know that:
The longest word in world
has 189, 819 letters and it is
the chemical name of the
largest known protein which
is “Titin”

28. LIPIDS

29. Lipids
- large biological molecules
that does not include true
polymers
- Hydrophobic in nature
- Fats, Phospholipids,
Steroids

30. Fat
- “triacylglycerol” and “triglyceride”
- consists of a glycerol molecule
joined to three fatty acids
- Glycerol is an alcohol; each of its three
carbons bears a hydroxyl group.
- A fatty acid has a long carbon skeleton,
usually 16 or 18 carbon atoms in length

31. Fat

32. Fat

33. Saturation of Fats
Saturated Fats
- Consists of one or more double bonds on the
side chains in a cis configuration
- Liquid at room temperature
- Plants and fishes fats

34. Saturation of Fats
Unsaturated Fats
- Consists of one or more double bonds on the
side chains in a cis configuration
- Liquid at room temperature
- Plants and fishes fats

35. Fat

36. Phospholipids
- similar to a fat molecule but has only two fatty acids
attached to glycerol rather than three.
- The third hydroxyl group of glycerol is joined to a
phosphate group, which has a negative electrical
charge in the cell
- Hydrophilic head
- Hydrophobic tail

37. Steroids
- lipids characterized by a carbon skeleton consisting
of four fused rings.
- Distinguished by the particular chemical groups
attached to this ensemble of rings

38. Steroids
- Cholesterol

39. Thank you !