Download Protein foods - Deans Community High School

West Lothian Council
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Protein foods
Proteins are important food chemicals that we can get
from plants and animals. Our bodies need protein for
growing and repairing damage. We can get protein
into our bodies by eating the foods shown below.
The foods shown above have all come from animals but some
people are vegetarians and do not eat food that has come from
animals. Vegetarians still need to eat protein because they still
need to grow and repair their bodies.
They need to eat lots of different
plants to make sure they get enough
protein. Soya is a protein that comes
from a plant and it is used in different
foods for example soya milk. Beans also
contain protein.
Write a heading and try the work below.
1. Our bodies need protein for ___________ and ________
______________.
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2. Make a list of foods that contain high levels of protein.
_______________________________________________
_______________________________________________
_______________________________________________
3. Vegetarians still need to eat protein because ____________
______________________________________________
4. Vegetarians make sure they have enough protein in their diet
by ___________________________________________
______________________________________________
5. Two foods that contain protein that comes from plants are
______________________________________________
6. Copy and complete the table below.
Name of food
name of animal or
plant it came from
Steak
Bacon
Eggs
Cheese
Beans
Milk
Chicken
Soya
7. Collect a data book and answer the questions below.
a) The page you would look at to find out about how much
protein there is in food is page __.
b) The food which contains the most protein per 100g is
___________________.
c) The food which contains the most fat per 100g is
__________________.
d) The food which contains the most carbohydrate per
100g is ___________________.
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e)
f)
g)
The food which contains no fat but 6g of carbohydrate
per 100g is ___________________________.
The two foods which contain no fat but 20g per 100g
carbohydrates are ____________________________
__________________________________________
The food which contains approximately the same amount
of all three food chemicals is ___________________.
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Testing foods for protein
Read
You may already know about testing foods:
 the benedict’s test turns from blue to orange if sugar is in
food.
 the iodine test turns from brown to black if starch is in food.
 the filter paper test goes transparent if fat is in food.
Chemists also have a way to test whether foods contain protein.
This test is called the soda lime test.
Watch your teacher demonstrate (demo 3.40) what happens in
the soda lime test. Remember the pH paper must be moist
because we need water present to test the pH of a substance.
substance
+ soda lime
moist pH paper
Write a heading and try the work below.
1. What test is used to find out if
a) sugar is in food - _____________________________
b) starch is in food - ____________________________
c) fat is in food - _______________________________
2. The name of the test that is used to find out if protein is
present in a substance is called the ___________________
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3. The pH paper need to be moist because ________________
______________________________________________
4. If the substance contained protein the pH paper turned
_________________.
5. This means that the gas made was acidic/alkaline.
6. Complete the sentences below.
To test if a substance contains protein we add s____- l____
to it and heat it. If the pH paper turns _________ we know
that protein is present. This means that an a__________
gas has been made in the reaction.
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Protein chemistry
Read
The diagram below shows the elements that are present in all
proteins.
N
C
H
O
Remember we are made of mainly water (60%) with some
protein so our bodies contain the same elements as proteins.
You may already know that starch is a very large molecule called
a polymer made by joining lots of glucose molecules together.
glucose
glucose
glucose
glucose
glucose
glucose
Proteins are also very large molecules called polymers. Proteins
are made by joining lots of molecules called amino acids
together.
Amino
acid
Amino
acid
Amino
acid
Amino
acid
Amino
acid
Amino
acid
The reaction to join small molecules into polymers is called a
polymerisation reaction.
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Write a heading and try the work below.
1. Use a data book and the chicken diagram on page 6 to make a
list of the elements that you would find in a protein.
______________________________________________
______________________________________________
2. A polymer is a large molecule/small molecule.
3. Explain how starch is made - ________________________
______________________________________________
______________________________________________
4. The small molecules that join together to make a protein
molecule are called _______________________________
5. Proteins are large/small molecules?
6. Copy the diagram to show how a protein is made from amino
acids joining together.
7. The name of the reaction that makes polymers like starch
and protein is called a _________________ reaction.
8. Go to the amino acids display and look at the models of amino
acids. Draw a picture of each molecule and beside it write
the formula.
Hint:
Black = carbon
Red = oxygen
Blue = nitrogen
White = hydrogen
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Polymerisation is the name of a chemical reaction to make
large molecules by joining small molecules together. A
polymerisation reaction is used to make proteins, starch
and also plastics.
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The Protein problem
Our bodies need certain amino acids to keep us healthy. We get
these amino acids by eating protein in animal and plant foods.
We have the same problem with eating protein as we do with
eating starch. Protein molecules are too big to get into our
blood. This means that our bodies have to break the proteins
up into small amino acids. This is called digestion.
amino protein
acid
The amino acids are small enough to get into our blood and
travel to places where they are needed to make new proteins
for example muscle protein, skin protein, nerve protein, kidney
protein, enzyme protein.
Write a heading and try the work below.
1. Protein molecules cannot get into our blood because _______
______________________________________________
2. The process that breaks big protein molecules up into amino
acids is called ____________________________.
3. Amino acids can get into our blood because _____________
______________________________________________
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