Carbohydrates

Carbohydrates make up 5% of the mass of the human body

Carbohydrates are the body's main 'fuel' for supplying cells with energy

Cells release this energy by oxidising a sugar (this sugar is glucose)

Glucose and other sugars are a type of carbohydrate

Sugars:

Glucose

Glucose is a sugar

Found naturally in sweet-tasting foods (eg. fruits and vegetables)

Different foods contain different sugars

Sucrose is the main sugar transported through plant stems and is extracted from sugar cane.

• They all taste sweet
• They are all soluble in water

Too much sugar in your diet can cause tooth decay because..

bacteria in the mouth feed on sugar, breaks it down and makes acids that dissolve the tooth enamel and breaks down the softer dentine underneath.

THEN... a cavity is formed in the tooth. Bacteria enters the cavity and enlarges it... then the decay reaches the nerves and... it hurts..

We get most of the carbohydrate in our diet from starch (and not sugars)

Starch

Starch is a large, insoluble molecule

Found as a storage carbohydrate in many plants (eg. potatoes, rice)

'staple diets' of people are basically starchy foods (eg. potatoes, rice, pasta, bread)

Starch is a made up of long chains of hundreds of gucose molecules joined together.

Starch is a polymer (chain) of glucose. Starch is only found in plant tissues.

Glycogen

Animal cells sometime contain a similar carbohydrate called glycogen.

Also a polymer of glucose

Found in tissues such as liver and muscle. Here, glycogen acts as a store of energy for these organs.

Cellulose

Polymer of glucose

Material that makes up plant cell walls

Humans cannot digest this

But it forms dietary fibre (roughage)

Keeps the gut contents moving, avoiding constipation and helps prevent diseases of the intestine (eg. Colitis and bowel cancer)