Protein

 

What is protein?

Our cells need proteins to do their jobs properly. Proteins are like tiny machines that make our bodies work. Proteins are big molecules made of smaller parts called amino acids. You can imagine proteins as chains, where each link is an amino acid. There are about 100 trillion cells in our bodies, and each cell has thousands of different kinds of proteins.

 

Protein-rich foods

Protein is one of the main food groups. It is needed by the body for cell growth and repair. Foods rich in protein include:

 

• fish
• meat
• milk
• eggs
• cheese
• beans

 

How much protein do you need?

Protein-rich foods are important to eat every day. Protein should be 10% to 15% of your daily energy intake, according to the World Health Organisation. This means about 53 g of protein per day for teenage girls, and 72 g for teenage boys.

 

Amino acids and their relationship with proteins

Protein is built from amino acids. There are 21 different amino acids. They are organic molecules that have carbon, hydrogen, oxygen, nitrogen, and sometimes sulphur. Your body can’t make 9 of these amino acids, so they are essential. The essential amino acids are:

 

• histidine
• isoleucine
• leucine
• lysine
• methionine
• phenylalanine
• threonine
• tryptophan
• valine

 

 

🥩 Knowledge Check: Protein & Amino Acids

How well do you know your macronutrients? Test your KS3 Biology knowledge below!

1. What are the building blocks of proteins called?

• Fatty acids
• Amino acids
• Glucose

2. Which chemical reagent is used to test for the presence of protein?

• Iodine solution
• Benedict's solution
• Biuret reagent

3. If protein is found in a sample, what color will the test solution turn?

• Blue-black
• Purple / Violet
• Brick red

4. Aside from muscle growth, what is another important role of proteins in the body?

• Providing insulation under the skin
• Making enzymes to speed up chemical reactions
• Storing genetic information in the nucleus

Reveal Answers

1. Amino acids (There are 20 different ones that build all human proteins).
2. Biuret reagent (A mixture of copper sulphate and sodium hydroxide).
3. Purple / Violet (The solution starts light blue and changes if protein is present).
4. Making enzymes (Enzymes are biological catalysts made of protein).

Summary:

 

• You need proteins to eat well. Foods that have a lot of protein are fish, meat, eggs and beans.
• Proteins help your body make new cells for growing, and fix broken tissues.
• Sports nutritionists know a lot about proteins and they help their clients get enough protein to heal their muscles.