Transcript Food and Diet

Food and Diet
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Why do we need food:
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Energy
Growth
Keep body functioning properly and healthy
All need food
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Autotrophs ( green plants) make own food
Heterotrophs (animals)– take in ready made food
Energy in Food
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Released during cellular respiration
Glucose and oxygen broken down in
mitochondria into carbon dioxide and water
and chemical energy released in form of ATP
to be used for work in the cell
Food types
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Carbohydrates
Proteins
Fats
Vitamins and minerals
(Water needed)
Carbohydrates
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Sugars (glucose and fructose) found in
fruits and some vegetables, cane sugar
(sucrose) in jams, cakes.
Starch is found in potatoes, rice, pasta,
mielies and other grains (cereals).
Cheapest, ready form of energy.
Elements = C, H, O.
Starch is a big molecule formed when many
glucose molecules join together
Carbohydrates cont.
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Excess converted to
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Glycogen ( formed when glucose molecules join
together) is stored in liver and muscles
Fat stored in fat depots under skin (adipose
tissue) or around kidneys and in abdomen.
Cellulose (plant cell walls). Important as
dietary fibre, acts as roughage to maintain
healthy digestive system; it keeps food
moving in gut.
Proteins
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Found in meat, fish, eggs, milk, cheese.
Beans, wheat and maize.
Needed to build cells and tissues, needed for
growth.
Elements = C, H, O and Nitrogen ( and
sometimes Sulphur).
Long chains of amino acids join together to
form proteins. Different chains of amino acids
form different proteins.
Proteins cont.
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Amino acids cannot be stored.
Those not used to form new cells have the
Nitrogen removed and the remaining part is
converted to glycogen to be stored or used to
release energy.
Fats
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Animal in meat, milk, cheese, butter, egg
yolk. Plant fats as oils – olive, sunflower.
Lipids = fats, oils.
Fat = solid at room temperature
Oils = liquid at room temperature
Provides most energy. Forms cell
membranes.
Elements = C, H, O.
Stored as adipose tissues under skin.
Vitamins
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Help the body to use proteins, carbohydrates
and fats
Found in food we eat, especially fruit and
vegetables.
A,D,E,K – soluble in fats
B,C- water soluble – can’t be stored
Needed in small quantities
See table in notes – do not need to learn
detail – data response questions.
Minerals
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Needed in small quantities
Present in food we eat
Needed to help nerves and muscles work.
See table in notes – do not need to learn
detail – data response questions.
Water
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Body = 70% water
Vital for life.
½ comes from food.
Drink 6-8 glasses of water a day
Dietary Fibre
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Plant cell walls
Fruit, vegetables, cereals
Becomes bulky when absorbs water.
Helps you feel full.
Helps food move along gut and push waste
out.
Prevents diseases like cancer of colon.