Proteins

4.3

Proteins

Introduction

Protein is a complex compound composed of carbon, hydrogen, oxygen and nitrogen elements
Most proteins also contain sulphur and phosphorus
Foods rich in proteins include fish, meat, milk, beans and eggs

Proteins

All proteins are composed of one or more polymers known as polypeptides
Each polypeptide is made up of monomers or small units known as amino acids
A polypeptide can consist of fifty to thousands of amino acid molecules
Amino acids are linked together through the condensation process
Dipeptides are composed of two amino acid molecules which are linked together by a peptide bond through the condensation process
In this process, one water molecule is removed
Further condensation can link more amino acids to form a polypeptide chain
- amino acid + amino acid \(\xrightarrow{\text{condensation}}\) dipeptide + water
- dipeptide + water \(\xrightarrow{\text{hydrolysis}}\) amino acid + amino acid
Each dipeptide can be broken down into an amino acid through hydrolysis
There are about 20 types of amino acids present naturally
Various types of polypeptide molecules can be formed from the 20 types of amino acids
This is because each type of protein differs in terms of the amino acid sequence in its polypeptide chain

Importance of Proteins in a Cell

Proteins are used to build new cells, repair damaged tissues and for the synthesis of enzymes, hormones, antibodies and haemoglobin
Proteins also form building blocks such as keratin in the skin, collagen in bones and myosin in muscle tissues
The breakdown of proteins or polypeptides by digestive enzymes gives us the energy to carry out our daily activities
Polypeptides can disintegrate into amino acids
This amino acid is then used again to build the protein molecules needed by the body

4.3

Proteins

Introduction

Protein is a complex compound composed of carbon, hydrogen, oxygen and nitrogen elements
Most proteins also contain sulphur and phosphorus
Foods rich in proteins include fish, meat, milk, beans and eggs

Proteins

All proteins are composed of one or more polymers known as polypeptides
Each polypeptide is made up of monomers or small units known as amino acids
A polypeptide can consist of fifty to thousands of amino acid molecules
Amino acids are linked together through the condensation process
Dipeptides are composed of two amino acid molecules which are linked together by a peptide bond through the condensation process
In this process, one water molecule is removed
Further condensation can link more amino acids to form a polypeptide chain
- amino acid + amino acid \(\xrightarrow{\text{condensation}}\) dipeptide + water
- dipeptide + water \(\xrightarrow{\text{hydrolysis}}\) amino acid + amino acid
Each dipeptide can be broken down into an amino acid through hydrolysis
There are about 20 types of amino acids present naturally
Various types of polypeptide molecules can be formed from the 20 types of amino acids
This is because each type of protein differs in terms of the amino acid sequence in its polypeptide chain

Importance of Proteins in a Cell

Proteins are used to build new cells, repair damaged tissues and for the synthesis of enzymes, hormones, antibodies and haemoglobin
Proteins also form building blocks such as keratin in the skin, collagen in bones and myosin in muscle tissues
The breakdown of proteins or polypeptides by digestive enzymes gives us the energy to carry out our daily activities
Polypeptides can disintegrate into amino acids
This amino acid is then used again to build the protein molecules needed by the body