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Proteins
Proteins:
• Organic compound
– Made up of C, H, O, N and some with S
– Proteins are made up of long chains of
the repeating units called amino acids.
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• There are 20 different types of amino
acids that make up all proteins.
10 are essential
to humans
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10 Essential Amino Acids:
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• The 20 amino acids combine in different
orders to make up different proteins
– Similar to the letters of the alphabet
• 26 different letters combine to make
500,000+ words
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Examples of foods rich in proteins:
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Foods which are the best sources of amino acids:
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S-T-E-A-K
S
T
T
S
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Blood
Hair protein-keratin
Muscle protein
Skin protein-collagen
E
K
A
E
In other words…………….
You are what you eat!!!!!!!
Or this…………….
Your choice………………….
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How much protein should you eat/day?
Multiply your weight in pounds by 0.4 to estimate how many
grams of protein you need each day.
For example, a female who weighs 120 lbs would need about 48
grams of protein (120 lbs x 0.4 = 48 grams).
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Food
Grams of protein
3 oz of tuna
22 grams
3 oz of hamburger
21 grams
3 oz of chicken
21 grams
1 cup yogurt
11 grams
2 Tbsp peanut butter
8 grams
1 cup of milk
8 grams
1 egg
7 grams
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Function of Proteins:
• Overall job of proteins is to:
–Build new cells
–Repair damages to our tissues and
cells
–Maintain our cells
–Help digest our food
–Regulate all cellular reactions
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• Proteins can be divided into two main types:
1. Structural Proteins:
• They build and support our tissues
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Examples of proteins:
Collagen…………………skin
Keratin……………………hair
Actin and Myosin………….human muscles
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• 2. Functional Proteins:
They perform specific functions within our bodies.
Example:
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Enzymes…speed up chemical reactions like digestion
Insulin….transports glucose into cells
Antibodies….destroy bacteria and viruses
Hemoglobin…transports oxygen to cells
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• Amino acids bond together into chains with peptide
bonds
lysine
• A type of chemical bond
Peptide
Bond
Amino acid
Dipeptide
Tripeptide
Polypetptide
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• All proteins have a very unique 3-D shape
– If 3-D shape is altered the protein will be
damaged.
• Extreme cold to collagen…………Frost bite
• Extreme heat to collagen…………3rd degree
burn
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Frying an egg:
Egg White:
10%
protein
Yolk:
15%
protein
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Levels of organization of a protein:
• 1st: Primary structure
• Proteins are made in a linear shape
– Straight line
• A specific chain of amino acids is put
together in the correct order according to
DNA’s code
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One single change…
Amino Acid Sequence
Normal -Threonine – Proline – Glucine – Glucine
Sickle
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-Threonine– Proline – Valine - Glucine
• 2nd: Secondary Structure
• The chain of amino acids becomes:
– Coiled
– Pleated
– A spiral
– Shape held in place with weak Hydrogen bonds.
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• 3rd: Tertiary Structure
– The amino acid chain gets a 3-D shape
– Each type of protein has its own 3-D shape
– If shape is altered the protein can not function
right.
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• 4th: Quaternary Structure
– This level is achieved when two protein
chains bond together to create a new protein.
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Enzymes:
-are catalyst
-they are complex proteins that speed up
all chemical reactions with our bodies.
Enzymes control
every reaction
Enzymes are responsible for:
within our
-cell respiration
bodies.
-photosynthesis
-Protein synthesis
-Digestion
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• Enzymes are substrate specific.
•
Substrates are substances
enzymes act upon like specific
types of food.
• Enzymes are specific types proteins.
Therefore enzymes have specific 3-D
shapes.
• For each substrate/substance there is
only one enzyme that can act upon it.
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Take the example of digestion:
Enzymes make the reaction of digestion
occur 10 million times faster than it would
without the enzymes.
Digest candy bar with enzymes….
20 min to 2 hours
Digest same candy bar without enzymes….
100 years
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Substrate: Substance that an enzyme
breaks down or acts upon.
Ex: Our candy bar
Due to their specific 3-D shape an enzyme
can only act upon one type of substrate.
There are different enzymes to break down
the peanuts, the chocolate, the creamy filling,
etc…..
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• Enzymes in the human alimentary canal
and what they digest:
Enzyme
Amylase
Maltase
Sucrase
Lipase
Protease / peptin
Substrate
Starch
Maltose
Sucrose
Lipids/Fats
Proteins
The name of enzymes end in the suffix “ASE”.
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Enzymes follow the lock and key hypothesis:
For every type of
substrate there is only
one type of enzyme to
break it down.
Just like there is only
one specific key which
fits into a specific type
of lock.
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Enzyme animation
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Let’s take a milk break…..
Lactase
Contains galactose and
lactose sugars
It’s a disaccharide
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-The specific 3-D shape of an enzyme is
called the active site.
-point on the enzyme
that “fits” around
or into the substrate.
-point where the
substrate is broken.
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Hyperlink
-Enzymes are not altered or used up during a
reaction.
-Enzymes can be used over and over again.
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Hyperlink
Frostbite
How environmental factors affect
enzymes:
Denaturing of enzymes:
-extreme heat or coldness, and strong acids
or bases can alter the shape of the active site
making it less effective. (breaks the hydrogen
bonds holding the 3D shape in place).
-this is called the denaturing of the enzyme
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Coenzymes:
-Vitamins and minerals can bond to the
enzyme and increase the rate of its
function.
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Competitive Inhibitors:
-Certain drugs can bond to the
enzyme and block the active
site rendering it useless
for doing its real job.
Example: The drug marijuana
contains the chemical THC. THC
temporarily bonds to enzymes in
our brain cells causing them to not
function correctly thus causing the
temporary feeling of being “high”.
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