They are one of the main dietary components.
• Formed of a single molecule. They are used
directly by cells.
– Fructose: Fructose is known popularly as fruit's
• They are formed by two monosaccharides.
– Lactose: It´s formed by glucose and galactose. We
can find lactose in the milk.
– Sucrose: It is formed by glucose and fructose. We
can find sucrose in honey. (it is the sugar we use
• They are formed by three or more
– Glycogen. It is the storage polysaccharide in animals.
Humans can use Glycogen as an energy source by
hydrolysis of the polymer using specific enzymes
– Starch. It is a storage polysaccharide in plant cells, we
can obtain it from potatoes.
– Cellulose. It is the constituent of the cell walls in cell
plants.We can not digest cellulose, because we lack
the specific enzimes that can hydrolize it.
• Monosaccharides can be directly absorbed in the
intestine, they dont need digestion.
• Disaccharides and polysaccharides can´t be direclty
absorbed, they must be digested until we obtain from
If we have high levels of glucose in the blood, part of
it turns into glycogen. Glycogen is accumulated in the
liver and inside the muscles.
• On the opposite if there are low levels of glucose in the
blood glycogen is broken into molecules of glucose.
Can you think examples of food rich in
• Cereals, fruit, vegetables, honey, sweets,
chocolate, sugar, potatoes, pasta, bread, rice.
• If we eat a lot of carbohydrates our body turns
them into lipids (fat)
• They have bigger energetic value but it is
more difficult to absorb them. They can be
stored in the body.
• What types of lipids are there?
• Fats: Saturated and unsaturated.
• Membrane lipids
• Regulatory lipids
• They don´t have double bonds between the
• Solid at environment temperature.
• We find them in animal and plant food. A lot of
these fats are bad for our health, specially trans
• E.g: palm oil, coconut oil.
• We can find them in whole milk, butter, ham, pig
meat, chocolates, pastries and processed foods
made with trans fat from partially hydrogenated
• They have double bonds between the carbon
• In vegetables and sea animals.
• They are usually liquid at environment
• They are healthier than saturated fats.
• E.g: Olive oil, dried fruits(avellanas,
almendras, pistachos), sunflower oil, blue fish
• Cholesterol Types???
• ( “bad cholesterol or LDL, good cholesterol or
HDL). Cholesterol can´t move on its own in the
body. It combines with a protein, and a
lipoprotein is formed.
• Fosfolipids. They form part of the cell
membranes of the cells.
Essential fatty acids
• What are they?
• Fatty acids that can´t be synthesized in the
body and must be obtained from food.
• Their names?
• Linoleic and linoleic acid. These basic fats are
used to build specialized fats called:
• Why are they important?
– They are important in the normal functioning of
• They are made of basic units called amino
• There are 20 different types of amino acids.
• There are 8 esential amino acids that our body
can not synthetise and therefore we have to
add them in the diet.
• In our diet we can have animal or plant
proteins. The animal proteins have a higher
nutritive value for us.
• Think examples of food rich in:
• Animal proteins:
– meat, fish, cheese, eggs, milk.
• Plant proteins:
– leguminous plants (beans, green beans, peas),
• Look info about this minerals, function, food
rich in them, and illnesses due to its lack.
• Page 21 activities 3 and 9
• Listen to cd activities 3 and 5
• Page 34 activity 2. Listen to it.
Unit 2 Review
• Why do we need to eat and drink?
• What type of nutrients are there?
– INORGANIC AND ORGANIC
• Can you give examples of carbohydrates?
• What polisacharide is known as the energy
store substance in plants?
• What about animals? What is our main energy
• What is fibre?
• Can we digest fibre?
• Give examples of food rich in fibre:
– Cereals, corn, wheat, rice, nuts, orange,
• What about proteins? What can you tell us
– Can we make all the amino acids?
• How much water do you drink daily?
• How much should you drink?
• Why is water necessary?
Tell us THINGS about VITAMINS!
• Give examples of sources of vitamins.
• Can any of the vitamins be made by the
• If you have high amounts of vitamin C, can
your body get rid of it ? How?
• What about vitamin A? What is its function?
• Vitamins E, K or D?
• Vitamin B12?
Do we use energy when we sleep?
• We need energy to maintain
the vital functions.