PROTEINS
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Prepared by:
Nur Fatihah Binti Din
4UPM
Learning Outcomes/Objectives:

State the elements in proteins.

State the various structure of proteins.

Explain the formation and breakdown of
dipeptides and polypeptides.

Explain the meanings of essential amino
acids and non essential amino acids.
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Introduction

Protein are large complex organic
molecules which play diverse roles in
living organisms.

Proteins made up of such elements as
carbon, hydrogen, oxygen, nitrogen,
sulphur and phosphorus.
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Amino acid + amino acid
Polypeptides + water
condensation
hydrolysis
hydrolysis
dipeptide + water
dipeptides or amino acids
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Examples

Protein sources: egg, meat, milk, yoghurt
and etc.
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Protein Structures
a) Primary structure
b) Secondary structure
- alpha-helix
- beta-pleated sheets
c) Tertiary structure
d) Quaternary structure
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a)

Primary structure
The linear sequence of amino acids in a
polypeptide chain.
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b)
i)
Secondary structure
Alpha-helix
- Three dimensional arrangement of amino
acids with the polypeptide chain in a cork
screw shape.
iv)
Beta-pleated sheet
- Polypeptide chains are arranged side by
side.
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c)

Tertiary structure
The overall three dimensional shape of a
polypeptide chain.
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d)

Quaternary structure
The combination of two or more tertiary
polypeptides that makes up a protein.
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Amino Acids

There have two types of amino acids:
i)
essential amino acids
ii) non essential amino acids


Essential amino acids are amino acids that cannot
be synthesized by the body. Example: Leucine
Non essential amino acids are amino acids that can
be synthesized by the body. There are 11-non
essential amino acids. Example: Alanine
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Thank You
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