Chapter 7: Proteins and Fats

Chapter 7: Proteins and
Define the following terms:
1. adipose cells—cells that sore fat
from foods and grow larger as they
store additional fat.
2. amino acids—chemical building
blocks of proteins that link together in
many arrangements.
3. cholesterol—fat-like substance in
all body cells; needed for many
essential body processes.
4. complete proteins—proteins that
contain all essential amino acids.
5. essential amino acids—amino
acids that the body needs but cannot
provide; obtained from foods.
6. fatty acids—chemical structures
that make up fats.
7. HDL—lipoprotein that picks up
cholesterol and takes it back to liver
for excretion; “good” cholesterol.
8. hemoglobin—protein with globular
shape; transports oxygen in blood to
all body cells.
9. hydrogenation—chemical process
that turns vegetable oils into solids.
10. incomplete proteins—plant proteins
that lack at least one essential amino acid.
11. LDL—lipoprotein that takes cholesterol
from liver to where needed in the body; can
accumulate too much; considered “bad”
12. lipoproteins—chemical “packages”
that transport fatty acids through
13. monounsaturated fatty acids—
unsaturated fatty acids with one
hydrogen unit missing.
14. omega-3 fatty acids—fatty acid in
fish oils, especially fatty fish; may
lower risk of heart disease.
15. saturated fatty acids—fatty acid
that contains all the hydrogen it can
chemically hold.
16. trans fats—fats produced when
oils are turned into solids in food
production; they increase LDL
cholesterol levels and may lower HDL.
17. triglycerides—type of lipid,
commonly called fats.
Answer the following questions.
• 1. Chemically speaking, what is
• Objects formed by amino acids that
perform different functions determined
by their shape.
2. What is hemoglobin?
• A protein with a globular shape that
transports oxygen in the blood to cells
in the body.
3. How does protein in food
become protein in the body?
• Once you’ve eaten a protein, your body
breaks the protein down into amino acids.
Then the amino acids can be reassembled a
human body protein.
• Protein digestion starts in the stomach.
First, strong stomach acid changes the
shape of the proteins. Protein digestion
continues in the small intestine until
individual amino acids become available.
• The amino acids can then be absorbed
into the bloodstream. Upon reaching
the cells, the amino acids are used to
make proteins for specific purposes.
4. Compare complete and
incomplete proteins.
• Complete proteins: foods with all the
essential amino acids.
• Incomplete proteins: foods that lack at
least one essential amino acid.
5. Summarize the work of
proteins in your body.
• Proteins play MANY roles in the body.
These are the highlights:
• Growth and maintenance—growing
new cells and repairing worn-out and
damaged parts. Some cells last only a
few days and must be constantly
• Enzymes—Without special proteins
called enzymes, chemical reactions
cannot take place at the necessary
• Hormones—Hormones are chemical
messengers that help regulate
conditions in the body. Some are made
from amino acids.
• One is the thyroid hormone that
regulates metabolism. Another is
insulin that helps maintain the level of
glucose (sugar) in your bloodstream.
• Antibodies—Antibodies are proteins
that fight invaders. The body creates
them as the need arises. In this way,
proteins are part of the immune system
and play a major role in fighting
• Fluid Balance—A cell’s life depends on
having fluid in the right amount. Too
much and the cell ruptures. Too little
stops their activity. Cells can’t move
fluids directly themselves so they build
proteins inside cells to attract water.
They send proteins into the blood
stream too maintain fluid levels there.
6. For teens, what percentage of
calories should come from
• 10—30 percent
7. What can happen if you eat
too much protein?
• Excess protein is stored as fat; if
amounts are huge, the body works
overtime to break down the extra
protein and remove the by-products.
8. What is a health expert likely to
recommend as good food
sources for protein? Why?
• Foods from plant sources because they
have less fat and usually cost less.
9. After a blood test, if someone says his
triglyceride level is high, what does
he mean?
• The level of fat in his blood is high.
10. Can you see fat in foods?
• You can see the fat on meats and
recognize it in butter, margarine, and
oil. Some fats can’t be seen because
they’re part of the food’s chemical
11. Why is it important to include
some fat in the diet?
• Fat helps the body absorb vitamins A,
D, E, and K.
• Body fat serves as a reserve supply of
• Body fat cushions and protects the
heart and other vital organs. It protects
bones from injury.
• A layer of body fat under the skin
provides insulation for warmth.
• Fat is a component of cell membranes.
• Because fats move slowly through the
digestive system, they help you fell full
longer after eating.
12. Use chemistry to theorize why foods
heavy in saturated fatty acids are
solid at room temperature.
• Since saturated fatty acids have all the
hydrogen the structure can hold, the
structure may be strong enough to hold
its shape.
13. If butter melts, does it become
polyunsaturated? Explain.
• No, because melting is only temporary;
the butter solidifies again at room
14. What happens to fats during
• They are broken down into fatty acids,
which move into the bloodstream and
head for the liver and tissues that need
them. Many are stored in fat cells.
15. What is cholesterol and how
do you get it?
• A fat-like substance in all body cells
needed for many essential body
processes; the body makes some but
it’s also in foods from animal sources.
16. Compare LDL and HDL.
• LDL—Low-density lipoprotein, or LDL,
takes cholesterol from the liver to
wherever it is needed in the body. If too
much LDL cholesterol is circulation,
excess amounts can build up in the
artery walls. This buildup increases the
risk of heart disease and stroke, which
earns LDL cholesterol the “bad”
cholesterol reputation.
• HDL—High-density lipoprotein, or HDL,
is more helpful. It picks up excess
cholesterol and takes it back to the
liver for excretion, keeping the
cholesterol from harming the body. For
this reason, HDL cholesterol is known
as “good” cholesterol. On a blood test,
you would want your level of HDL to be
high but your level of LDL to below.
17. What effect does fat have on
• Saturated fat appears to raise LDL
levels; polyunsaturated fat may help
lower cholesterol levels;
monounsaturated fat appears to lower
LDL and help raise HDL.
18. How is a trans fat made?
Hydrogen is added to the unsaturated
fat in vegetable oil, making it
saturated and solid.
19. If a teen needs 2,500 calories each
day, how many grams of fat does
that allow? If needed, show math.
• 67—97 g of fat (2500 x .25 = 625
calories divided by 9calories per fat
gram = about 69 g;
• 2500 x .35 = 875 divided by 9 = about 97
20. Why do some people gain weight
when cutting down on fat?
• Some increase the amount of fat-free
and low-fat foods they eat and thereby
consume more calories.

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