Carbohydrates

 

Types of carbohydrates

Carbohydrates are compounds that are in living things. They have molecules with carbon, hydrogen and oxygen atoms.
Carbohydrates give energy to your body. They power the processes in your body.

 

Your body changes carbohydrates into glucose, which can go into the bloodstream.

Then, glucose molecules go in the blood to the cells in your body where they are used for respiration. The glucose reacts with oxygen, giving energy.

There are two kinds of carbohydrates:

 

• Simple carbohydrates (also called sugars) These are simple sugar molecules, like glucose, fructose and sucrose. You can get them from sweet foods like chocolate, milk and fruit.
• Complex carbohydrates (also called starch) These are long chains of sugars joined together. You can find them in foods like bread, rice, pasta and potatoes.

 

Your body digests starch and sugars differently:

 

• Sugary foods and drinks can be easily changed into glucose. This can go into the bloodstream quickly to give a short energy boost.
• Starch is a long, complex molecule that is harder to change into glucose. This means that it gives energy more slowly. That is why it is called a slow-release carbohydrate.

 

How much carbohydrate do you need?

The World Health Organisation (WHO) advises to get half of your energy from carbohydrates. This means about 260g of carbohydrates every day for a moderately active teenager.

 

🍞 Knowledge Check: Carbohydrates

Test your understanding of sugar, starch, and food chemistry.

1. Which of these is a 'Simple Sugar' used directly by cells for respiration?

• Starch
• Glucose
• Cellulose

2. Complex carbohydrates like starch are made of long chains of:

• Amino acids
• Fatty acids
• Sugar molecules

3. If you add Iodine to a piece of bread, what colour change indicates starch is present?

• Blue to Brick-Red
• Orange-Brown to Blue-Black
• Stays Light Blue

4. To test for glucose using Benedict's solution, what vital step must you perform?

• Shake it for 2 minutes
• Heat it in a water bath
• Freeze it overnight

5. Why is starch a better energy storage molecule than glucose?

• It is insoluble and doesn't affect water balance in cells.
• It tastes sweeter than glucose.
• It is a liquid at room temperature.

Click to Reveal Answers

1. Glucose (The basic fuel for respiration).
2. Sugar molecules (Starch is a polymer of glucose).
3. Orange-Brown to Blue-Black (The classic iodine test result).
4. Heat it in a water bath (Benedict's reagent requires heat to react with reducing sugars).
5. It is insoluble (Starch can be packed away in cells without causing them to swell with water).

 

Summary:

 

• Carbohydrates are compounds that are found in living things. Their molecules are made up of carbon, hydrogen and oxygen atoms.
• Carbohydrates are an important source of energy in a healthy diet. Starchy and sugary foods are high in carbohydrates.
• Athletes eat different types of carbohydrate at different times in their training schedules.