Chapter 6: Proteins
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A nutrient made up of carbon, hydrogen,
oxygen,and nitrogen.
Proteins are composed of Amino Acids linked
together into a chain.
Although all amino acids have the same basic
structure, the 4th carbon bonding site
distinguishes the amino acid.
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Figure 6-1: Amino group and Acid group
The Simplest Amino Acid: Glycine- only
contains a hydrogen atom for the side group.
(Refer to Figure 6-2)
There are 20 common amino acids, 9 of
which are essential. (What does this mean?)
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Condensation reactions link the amino acids.
Di-peptide Bond: 2amino acids bonded
together
Tri-peptide bond: 3 amino acids linked
together.
Poly-peptide bond: several amino acids linked
together. Most of the proteins that make up
your body are poly-peptide bonds,
For example Insulin (Refer to figure 6-4)
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Amino acids are linked together in
different sequences to form different
proteins in the body.
That is why there are so many
different proteins.
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There are an estimated 30,000
different kinds of proteins.
Each human body is different because
of the amino acids sequence that is
determined by genetics.
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Deoxyribonucleic Acid (DNA) serves as a
template for making strands of MRNA.
Messenger RNA carries a code which specifies
the sequence of amino acids attaching
together in a chain to form proteins.
MRNA attaches to a ribosome and presents
its list, so the amino acids then line up in the
proper order to form the correct protein.
Transfer RNA- is responsible for collecting
the amino acids from the cell fluids and
bringing them to the MRNA.
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The amino acids then line up in order, the
enzymes bind them together to form a
protein strand, and the strand is released.
There is a circumstance where there is an
error in sequencing of the amino acids.
Valine is in the place of glutamic acid.
What is the form of anemia
called?
 (Refer
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to Figure 6-8)
The red blood cells appear crescent in
shape and interfere with oxygen
transport and blood flow.
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Page 185
When glucose and fats are limited, the cells
are forced to use amino acids for energy and
glucose.
When the amino acids are broken down, they
are first deaminated.
Deamination- stripping of the NH2 group
Nh2 group is converted into ammonia by the
liver-----liver combines it with co2, which
converts it to urea-----bloodstream--- to
kidneys---filtered out in the urine.
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The body needs a great amount of water to
aid the kidney in ridding itself of the urea.
Someone on a high protein diet must
consume high amounts of water to dilute and
help excrete the urea.
If you consume a high protein diet, and not
enough water, you are risking dehydration.
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High quality proteins contain all essential
amino acids and are referred to as
◦ Complete Protein Foods: all animal derivatives.
 (meats, fish, poultry, eggs, dairy products)
◦ Incomplete Protein Foods: lack one or two amino
acids: Vegetables, grains, nuts, seeds,and
legumes.
Two incomplete protein food sources
that lack different amino acids and
provide all essential amino acids
 Vegetarians will eat proteins from
different incomplete sources at some
point during the day and receive all
amino acids.
 Refer to Handout
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Page 181.
1. Building and Repairing Body Tissues
◦ Protein forms the building blocks of the muscles,
blood, and skin.
◦ Collagen is a protein substance that must be layed
down for building bones and teeth, and it provides
the material of ligaments and tendons.
◦ Protein helps to repair or replace damaged cells.
 Ex- muscle tissues use protein to build larger
muscles and stronger muscles after exercise.
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2. To make Enzymes-which facilitate
chemical reactions.
◦ Chapter 3 focused on several digestive
enzymes that break down the 3 energy
nutrients.
◦ These enzymes are protein substances.
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3. Some Hormones are made of
Protein- chemical messengers that
send a message to facilitate a
chemical reaction.
◦ Ex- Insulin regulates blood glucose
 Thyroxin regulates metabolic rate
 Calcitonin regulates blood calcium
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Fluid Balance-large proteins of the
blood don’t normally cross through the
walls of the blood vessels.
Protein is hydrophillic and attracts water,
which helps to maintain osmotic pressure
in the blood stream.
When someone is suffering from extreme
malnutrition, the blood proteins will seep
out of the blood vessels and into the
tissues, resulting in edema.(because the
water follows the protein into the tissues
and causes the swelling).
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Acid-Base Balance-protein
accepts or release hydrogen
ions, thereby maintain
acid/base balance of the body
fluids.
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Transporters- Proteins are
responsible for carrying nutrients
and other substances throughout
the body.
◦ Examples Lipoproteins: carries? __________
 Hemoglobin: carries? ___________
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7. Antibodies-which defends the body
against disease or foreign bodies.
◦ When the body detects an invading
antigen, it produces antibodies which
work quickly to fight off the antigen.
Once the body has made the specific
antigen it remembers to make them each
time the body comes in contact with that
antigen and immediately fights it off.
◦ Bonus Question- Identify a case where
the body tries to fight off an antigen,
when this is undesirable.
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Source of Energy and Glucose
9.Other Roles-Blood clotting (fibrin) and
 Vision (opsin)
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Protein energy malnutrition- PEM
(Refer to Table 6-3)
 Marasmus
 Kwashiorker
Heart Disease
 Cancer
 Bone Losses and Osteoporosis
 Weight Control
 Kidney Disease
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 .8
grams/Kg. of body weight
 Athletes need about 1.2 to 1.7
grams/kg of body weight
 For
someone who weighs 195 lbs.
and is an elite athlete, needing
the greatest amount of protein,
how much should he get daily?
 Protein
Powders- When supplements
may slightly increase protein synthesis but it
does not enhance athletic performance
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Amino Acid Supplements-
large doses
cause diarrhea.
An excess of one amino acid creates a demand for
a carrier for other amino acids, possibly resulting
in a deficiency of it.