Transcript Amino acids - Life Science Classroom

BIOLOGICAL COMPOUNDS
&
NUTRIENTS
1
Organic molecules
• Molecules are called organic compounds if
they:
• contain carbon-to-carbon bonds AND
• are made exclusively by plants and/or
animals,
• (This naturally excludes compounds like
CO2, which is made by living organisms,
but not exclusively— plenty-of other
processes produce CO2).
2
INORGANIC COMPOUNDS
ORGANIC COMPOUNDS
1. Do not contain the
1. Always contain
element CARBON
the element
(except as single
carbon (forming
carbon atoms - CO2 )
chains)
2. They are usually raw 2. Made by Living
organisms
materials from the
environment
4. Do not burn
4. Burn
(Combustible)
3
ORGANIC COMPOUNDS
• Contains CARBON with either a
HYDROGEN or another/other CARBON/S
attached to it.
• CO2: INORGANIC
• CH4 ORGANIC
• CCl4: ORGANIC
• C6H12O6: ORGANIC
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CARBOHYDRATES
• "CARBO" = CARBON;
"HYDRATE" = WATER
• Hence the elements
are Carbon, Hydrogen
and Oxygen and the
• ratio of Hydrogen to
oxygen is ALWAYS
2:1 (2 hydrogen's for
every 1 oxygen, as in
water)
C6H12O6 = glucose C12H22O11 = sucrose
Formula = CnH2nOn
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Monosaccharides
– the monomers of carbohydrates
• Monosaccharides (single sugar units)
E.g., Glucose, fructose, galactose
• Properties
Soluble in water, sweet, can form crystals
• Functions
Serve as a source of energy e.g. glucose.
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• Disaccharides are made from monosaccharides as follows
• GLUCOSE + FRUCTOSE sucrase (enzyme) SUCROSE + H2O
(found in
SUGAR – FOR TEA )
• GLUCOSE + GLUCOSE maltase (enzyme)
(found in GERMINATING SEEDS )
• GLUCOSE + GALACTOSE lactase (enzyme)
(found in DAIRY - MILK
)
MALTOSE
LACTOSE
+ H 2O
H 2O
WATER
• In each case, enzymes remove one ______________
molecule by a
CONDENSATION
process called __________________
to join the two smaller molecules
together.
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Disaccharides
• Physical properties: Soluble in water
and sweet to the taste.
• When 2 monosaccharides react together
they form a disaccharide (meaning two
sugar units). This reaction is known as
condensation and this reaction involves
the removal of a water molecule. glycosidic bond
CONDENSATION
- H2 O
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POLYSACCAHRIDES
• A polysaccharide is a POLYMER ("poly" = many), made
of many single units or monosaccharides called
MONOMERS
• Polysaccharides are formed by condensation reactions
where many monosaccharides are joined together, in a
process generally called POLYMERISATION.
Polysaccharides are hydrolysed (by the addition of
water) into simple monosaccharides .
• They are insoluble in water and are not sweet.
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Examples of polysaccharides
are
•
•
•
•
•
CELLULOSE - CELL WALLS – PRIMARY
CELL WALLS –SECONDARY
LIGNIN -(WATERPROOF)
GLYCOGEN - IN LIVER AND MUSCLES
STARCH –IN LEUCOPLASTS
PECTIN - IN MIDDLE LAMELLA
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• Made by CONDENSATION of many
glucose units only
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Physical properties of
Carbohydrates
• Simple carbohydrates are soluble in water
• Polysaccharides are generally insoluble
in water
• Monosaccharides and most disaccharides
taste sweet
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FOR ALL ORGANISMS
CHEMICAL POTENTIAL
ENERGY
1. They are a good source of __________________
____________________
energy, such as glucose.
2. They form part of nucleic acids DNA and RNA.
FOR PLANTS
FOR ANIMALS
3. Plants store food as
3. Animals store food as
GLYCOGEN
STARCH
_______________
in seeds and
____________in
muscles and liver.
bulbs.
4. Plants transport food as
4. Animals transport food as
BLOOD
glucose in a tissue called
glucose in the ____________
PHLOEM
STREAM
__________________.
______________.
5. Carbohydrates like
5. Carbohydrates like
CELLULOSE & ____________
LIGNIN
CHITIN
_____________
_____________
form part of the
form part of cell walls.
exoskeleton of insects.
6. __________________
in plants
7. __________________
forms an
PECTIN
CELLULOSE
keeps cells glued together
important source of roughage in
our diets.
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LIPIDS OR FATS
• C, H & O
• Ratio of
H:O = >2:1
• 1 Glycerol
and 3 fatty
acids
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1 = GLYCEROL
2 = FATTY ACID
3 = ESTER BOND
THE DIFFERENT FATTY ACIDS MAKE UP THE DIFFERENT LIPIDS
•
SHORTER FATTY ACIDS FORM OILS
•
LONGER FATTY ACIDS FORM SOLIDS (BUTTER)
•
VERY LONG FATTY ACIDS FORM WAXES
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• Fatty acids are classified as being SATURATED OR
UNSATURATED
SINGLE
• Saturated Fatty Acids have _______________________
carbon –
to-carbon bonds so they are completely saturated with hydrogen.
ANIMAL
These tend to occur in ____________________
fats like butter and
cream, and they generally increase cholesterol in the body. Limit
them in your food!
• Unsaturated fatty acids have ________________
C-to-C bonds, so
DOUBLE
some spaces are not saturated with hydrogen. They occur mainly in
PLANT
_______________
oils like canola oil and olive oil, etc., and they
decrease cholesterol. It’s much healthier to consume these fats 16
than animal fats.
Cholesterol and heart disease:
• Your body needs cholesterol to make new
cells, insulate nerves and produce some
LIVER
hormones. Normally the _________makes
all the cholesterol you need, but people
also take in cholesterol with foods like
EGGS
MILK
_________,
_______________
and
RED MEAT
________________________.
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Cholesterol and heart disease:
• High cholesterol can
cause a
cardiovascular
problem called
ATHEROSCLEROSI
S - fat is deposited
between the
epithelial and muscle
layer of blood
vessels, causing the
lumen / cavity to
become
NARROWER
_________________
so a partial blockage
develops & slows
down blood flow.
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• In the heart, this causes a reduced supply of oxygen to
PAIN
the heart muscle, causing _________
called
ANGINA
HEART
ATTACK
• _______________.
A __________
__________
will result if the obstruction causes a complete blockage.
• Cholesterol is transported in the blood in 2 forms;
• LDL's (Low Density Lipoproteins): also called
_______________
cholesterol. This contains little protein
BAD
and much cholesterol and Is the chief agent causing
BUTTER
arterial blockage (e.g., ________________,
CREAM
_______________)
•
HDL's (High Density Lipoproteins): Also called
____________
cholesterol. This form has lots of proteins
GOOD
and little cholesterol. If actually works to ___________
REDUCE
fatty deposits in the blood stream.
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• REMEMBER: High cholesterol levels in
the blood stream cause NO SYMPTOMS at
all
• Everyone over the age of 20 should have
their cholesterol levels checked at least every
5 years, thereby decreasing their chances of
heart disease. It's definitely also advisable to
ANIMAL
decrease _____________________
fats and
INCREASE PLANT FATS, fruit and
vegetables in the diet.
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• Fats or lipids are formed when I glycerol and 3 fatty
acids are joined by enzymes by means of
CONDENSATION
_______________________________.
• 1 glycerol + 3 fatty acids
1 lipid + 3 H20
HYDROLYSIS
• The process ___________________can
be used to
break the lipid down again:
• 1 lipid + 3 H20 molecules
1 glycerol + 3 fatty acids
• 2.4 Physical properties of lipids:
WATER
• They are insoluble in _______________________.
• They are soluble in
ALCOHOL, ETHER, AMMONIA
______________________________________
etc.
• They are hydrophobic, i.e.,
REPEL WATER
_________________________.
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Biological importance of Lipids:
FOR ALL ORGANISMS
CHEMICAL POTENTIAL
1. They are the best form of _______________________________
energy in
the form of stored fats). Gram for gram, they have more than TWICE
the energy in carbohydrates).
CELL MEMBRANE
2. They form part of all _______________________
in plants and animals.
3. Lipids are important for waterproofing leaves and insects by means
CUTICLE
of a waxy layer called the _______________________________.
FOR ANIMALS
PROTECT delicate organs like kidneys and eyes from injury.
1. Lipids __________
INSULATE
2. Lipids under our skin ______________________________
the body
against heat loss in cold weather.
3. Lipids are important for the absorption of fat-soluble
VITAMINS
________________
like Vit. A and D.
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PROTEINS
• C, H, O,
NITROGEN
(+ P,S)
• No fixed H:O ratio,
varies greatly.
• Consist of the
monomers amino
acids joined
together.
There are 20 natural
amino acids, used to
construct MANY, MANY
proteins.
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Monomers of Proteins
AMINO
ACIDS
• The ___________________
__________
form the basic molecules (monomers) of
which proteins are constructed.
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DIPEPTIDE
TRIPEPTIDE
POLYPEPTIDE
A molecule is only called a protein if it contains more
50
than _________
amino acids.. The
INSULIN
Smallest known protein is ____________,
which has 51
amino acids; others have thousands.
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Dipeptides
• There are 20 naturally occurring amino acids
which we call the essential amino acids for life.
• The amino acid MONOMERS are used to build up
proteins.
• Amino acids join to each other by a
CONDENSATION REACTION. WATER is
removed in a reaction between the amino group of
one amino acid and the carboxyl group of the
other.
• They are broken down by means of HYDROLYSIS
• The bond between the amino acid molecules in a
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protein molecule is called a PEPTIDE BOND
HYDROLYSIS
• Notice in the drawing below, we have
shown the HYDROLYSIS, where water is
added to break up sucrose into two
monosaccharides, one glucose and one
fructose molecule.
Sucrase enzyme
+
HYDROLYSIS
+ H2 O
Amino acids are joined together by
CONDENSATION
_____________
and broken down by
____________________
HYDROLYSIS
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PHYSICAL PROPERTIES - PROTEINS
MACRO-MOLECULES
• They are ____________________
(large)
pH
• Sensitive to changes in _____
(acidity/alkalinity)
• Sensitive to TEMPERATURE
______________ (cold does
not affect the structure but high
temperatures can cause a breakdown in
their structure called _________________
DENATURATION
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The Denaturing of Proteins:
Normal protein (with its
INTRA-MOLECULAR
_______________________
bonds intact
and able to function.
Denatured Protein:
BROKEN
bonds are __________
so it loses
SHAPE
its ___________
and can’t
function.
•
•
CAUSES:
pH
Temperature
increase
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Biological importance of Proteins:
FOR ALL ORGANISMS
PROTOPLASM
1. Proteins form part of ______________________,
the living substance in cells.
CELL
MEMBRANES
2. They form part of all _____________
__________, e.g., nuclear membrane.
ENZYMES speeding up biochemical reactions.
3. They act as ___________,
CHROMOSOMES
4. They form a structural part of _________________________,
together with
DNA.
ENERGY SOURCE
5. They can be used as a _______________________
when carbohydrates and
lipids are in short supply. This is for emergencies only.
FOR ANIMALS
1. Some hormones like INSULIN
_________ are proteins (it controls blood glucose
level)
PIGMENTS like melanin or haemoglobin.
2. Proteins can be ___________
3. Some proteins act as part of the immune system, e.g.,
ANTI-BODIES
____________________
in blood.
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Polymers
• All organic compounds are built up into
POLYMERS by the process of
CONDENSATION
_______________________
and can be
broken down by _________________,
HYDROLYSIS
e.g.,
during digestion.
• METABOLISM consists of building up
processes called
ANABOLISM
_____________________________
and
breaking down processes called
CATABOLISM
________________________________.
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FOOD TESTS
• All the tests described below are
CONTROL TESTS to show what a positive
result looks like - we will be using the actual
substance we are lasting for with the
appropriate method.
• This will show you what a positive test looks
like, so that further tests on food samples
can be COMPARED with these controls.
• When you are testing a food sample, DO
NOT ADD THE SUBSTANCE TESTED
FOR!
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• Two procedures to be followed when testing
food samples for various compounds:
•
CRUSH IT OR CUT IT FINELY TO INCREASE THE
SURFACE AREA OF THE REAGENT TO REACT WITH
___________________________________
•
ADD WATER TO CREATE A LIQUID MEDIUM FOR
THE CHEMICAL RECTIONS TO WORK IN
___________________________________
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GLUCOSE TEST
•
•
•
•
•
•
•
•
•
•
Place a small amount of glucose powder (or food) into a test tube. Addwater
& shake it. Light a Bunsen burner.
Add a few drops of BENEDICTS SOLUTION to the mixture and shake.
Use a test tube holder to heat the solution over the flame, moving it
constantly and keeping the open end of the test tube away from people.
(Heat Is used here to
SPEED UP THE RATE OF THE REACTION
____________________________________________________
Record colour changes. DO NOT overheat the mixture - stop when it boils,
RESULT:
No glucose BLUE
some glucose GREEN
more glucose YELLOW
lots of glucose REDDISH-ORANGE
CONCLUSION
IF A SUBSTANCE TURNS ORANGE IN THE
PRESENCE OF BENEDICT’S SOLUTION
AND HEAT, IT CONTAINS GLUCOSE
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TO TEST FOR THE PRESENCE OF STARCH:
• Place a small amount of starch powder (or food) Into a test tube and
add a little water. Shake it. No heat is needed - why?
THE REACTION IS FAST ENOUGH
____________________________
• Add a few drops of IODINE SOLUTION and shake it.
• Record colour changes.
• RESULT:
BROWN IODINE CHANGES TO BLUE-BLACK
• ______________________________________________________
• CONCLUSION:
ANY FOOD THAT TURNS FROM BROWN TO BLUE-BLACK IN THE
OF IODINE CONTAINS STARCH.
• PRESENCE
______________________________________________________
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Biological Compounds Page 9
• All organic compounds are built up into
POLYMERS by the process of
CONDENSATION
_______________________
and can be
HYDROLYSIS
broken down by _________________,
e.g., during digestion.
• METABOLISM consists of building up
processes called
_____________________________
and
ANABOLISM
breaking down processes called
CATABOLISM
________________________________.
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TO TEST FOR THE PRESENCE OF PROTEINS:
•
•
•
•
•
•
The Biuret test:
Put a small amount of raw egg white (or food) into a test tube. Add a little
water and shake It gently.
Add a few drops of COPPER SULPHATE solution (CuS04).
Use a different dropper to fill about one third of the test tube SODIUM
HYDROXIDE solution (NaOH).
Go back to your group and shake the test tube when you get there, note
colour changes.
RESULT:
•
COLOUR CHANGES: BLUE TO VIOLET
____________________________________________________________
•
CONCLUSION:
•
ANY FOOD THAT TURNS VIOLET WITH
CuSO4 (COPPER SULPHATE) AND NaOH
(CAUSTIC SODA) CONTAINS PROTEIN
____________________________________________________________
•
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Page 11
FOOD
TEST
Glucose
Starch
Proteins
Biuret
test
REAGENT
HEAT?
Positive
test:
Colour?
Negative
test:
Colour?
BLUE
BENEDICTS YES
GR/YE/OR
IODINE
NO
BLUE-BLACK BROWN
NO
MAUVE/
PURPLE
CuSO4
+
NaOH
NONE
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Food labels
• To compare different foods, use the
Nutritional content per 100g (this is also
easily converted into % (30g per 100g =
30%
• Keep fat content to a minimum
• Water is seldom included (if it adds up to
less than 100g, the remainder is water).
• Carbohydrates include only digestible
(starch, sugar), not fibre, cellulose
• Go for fewer refined carbs (like sugars)
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WORKSHEET RELATING TO FOOD LABELS
Examine the label of a Aero chocolate bar
Nutritional
Per 45g
Per 100g
information
serving
Energy
2196 kJ
989 kJ
Carbohydrates
57,6 g
26 g
Fats
29,9 g
13,4 g
Proteins
6,5 g
3,0 g
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1. Which compound forms the majority of this food
item? __________________
(1)
CARBOHYDRATES
2. What is the main specific carbohydrate in an Aero
bar likely to be?
AERO IS A CHOCOLATE AND IS MADE (2)
• LACTOSE.
______________________________________
OF DAIRY AND ADDED SUGAR (SUCROSE)
3 Use the serving size to calculate the percentage
fats in this food item. Show your working.
29,9/100 X 100 = 0,299 X 100 = 29,9% (OR 29,9G
OF 100G = 29,9%)
(3)
4 Do you think that these fats are likely to be
saturated or unsaturated? Give a reason for your
answer.
SATURATED: CHOCOLATE CONTAINS CREAM
WHICH CONTAINS SATURATED FATS
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(2)
• If a person needs 150 g of protein in a day to maintain her
body, how many of these bars should she consume daily if
she eats nothing else? Give your answer to the nearest
whole bar.
150G/3G = 50 = 50 BARS.
_____________________________________________ (3)
• Would you suggest that she eats Aero bars in order to
obtain the correct protein content in her diet? Give a reason
for your answer.
NO WAY! ALTHOUGHS HE GETS THE REQUIRED
PROTEINS SHE WILL EAT TOO MUCH FAT AND
CARBOHYDRATES.
• ____________________________________________(3)
• Calculate the percentage water in this food item
100 – (57,6 + 29,9 + 6,5) = 6/100 = 6%
• __________________________________________
(2)
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Vitamins
Vitamins: Group of complex organic
compounds, needed in small
quantities that help your body
maintain normal metabolism,
growth, and development.
Vitamins mainly made by plants
and animals obtain theirs from
the food they eat.
• They have no energy value - taking a
vitamin supplement can't "give you energy",
but can optimise certain functions like energy
release from food.
• They act as important REGULATORS in
body processes and are essential in the
maintenance of good health.
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Vitamins
Two Groups of Vitamins:
• Water-Soluble
• Fat-Soluble
Water-Soluble Vitamins:
• Vitamins that dissolve in water
and are NOT stored in your body
for future use
Vitamin B and Vitamin C
Vitamins
Fat-Soluble Vitamins:
• Vitamins that dissolve into and
are transported by fat
• They can be stored in fat
tissue, the liver, and the
kidneys.
• Vitamins A, D, E, and K
Examples of Fat-Soluble Vitamins:
• Vitamin A:
• Essential for forming of a pigment in
the rods of the eye (retina) to see in
dim light. Maintains good vision,
promotes body cell growth, helps
protect teeth
– Food sources: green vegetables
(carrots, spinach, gem squash), dairy
products
– Deficiency diseases: Nightblindness
Vitamin B3:
Acts as a co-enzyme in cell
respiration, assisting energy
release from food.
– Food sources: Red meat,
unrefined cereals, Marmite,
Bovril
– Deficiency disease:
Pellagra – skin rashes, redness,
swollen red tongue, diarrhea
Examples of Water-Soluble
Vitamins:
• Vitamin C: Essential for
formation of collagen and
plays a role in immunity
(fights against infection,
maintains healthy gums,
strengthens and maintains
blood vessel structure)
– Food sources: citrus
fruits, tomatoes,
strawberry, pineapple,
guava, leafy vegetables
Deficiency
disease: Scurvy &
anaemia
Bleeding gums,
poor wound
healing, frequent
infections
• Vitamin D:
Essential for
absorption of
calcium and
phosphorus and thus
hardening bones and
teeth
Food sources: eggs,
cod liver oil, salmon,
butter, margarine,
fortified breakfast
cereal. Other sources
include sunlight
Deficiency disease:
Rickets (children) - soft
bones causing bow-legs or
knock knees
• Vitamins found in all the major food groups
but, NO ONE FOOD CONTAINS ALL
THE REQUIRED VITAMINS.
• A balanced diet is the best way to ensure
that one gets all the necessary vitamins.
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IMPORTANCE OF WATER IN NUTRITION
PHOTOSYNTHESIS
1. RAW MATERIAL FOR _______________________
(and a waste product of cellular respiration)
2. CHEMICAL REACTIONS IN CELLS ALWAYS TAKE
PLACE IN THE MEDIUM OF WATER. Water acts as a
SOLVENT
______________________.
Ions, atoms and molecules
are SOLUTES which dissolve in water before being
able to react.
3. WATER CAN BE INVOLVED IN A CHEMICAL
HYDROLYSIS
REACTION CALLED _______________
("hydro" =
water; "lysis" = to dissolve or break down Water
actually is involved in the reaction (usually digestion)
and it splits a larger molecule into smaller molecules.
e.g. Maltose + water
=
glucose
+ glucose
maltase (enzyme)
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A TRANSPORT
4. WATER IS _________________________
MEDIUM FOR SUBSTANCES, e.g. foods,
gases and waste products in the blood
circulation of animals or in the phloem of plants.
5. WATER EVAPORATES FROM THE SKIN
AND THEREFORE COOLS THE BODY (IT
HELPS THE BODY TO REGULATE ITS
TEMPERATURE)
6. WATER ACTS AS A
LUBRICANT
_______________________,
REDUCING
FRICTION, e.g. in the joints of the body,
allowing freer movement.
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MINERALS
• 20, inorganic, NOT MADE BY PLANTS
OR ANIMALS
• Macro-elements are elements required in
LARGE QUANTITIES BY AN
ORGANISM.
• Micro-elements are elements required in
SMALL QUANTITIES BY AN ORGANISM
(they are also known as TRACE
ELEMENTS).
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Main purpose
MACRONUTRIENTS

Nitrogen*

Magnesium

Phosphorus
Calcium
Essential for formation
ACIDS
of AMINO
________________
which make up

PROTEINS
___________________


Essential for
CELL MEMBRANE
___________________
formation



All three are needed 

for
HARDENING

_____________________
OF BONES

_____________________
AND TEETH
_______________



SOURCE
DEFICIENCY

Milk
Cheese
MEAT
___________
Stunted
growth
 CHLOROSIS
___________
in plants
(yellow
leaves)
Milk
Eggs
MEAT
____________ All three leads
Milk
to
RICKETS
Eggs
_______________
CHEESE
____________ in children soft
Milk
bones. They
Eggs
work with
CHEESE
____________ Vitamin D
_____
GREEN
____________
VEGETABLES
____________
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Iron*
Iodine
MICRO-NUTRIENTS

Liver

Part of
____________
ANAEMIA
HAEMOGLOBIN
MEAT

___________
___________________
Too few red
EGGS
in red blood cells

___________
blood cells,
RAISINS

____________
lack of
GREEN VEGG
____________
energy.
GOITRE
 Part of the
______________
SEA FOOD
hormone
Swollen
IODISED
THYROXIN
___________________
thyroid gland,
TABLE SALT
that regulates
VEGETABLES tiredness.
metabolic rate
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