Download Macromolecules - WordPress.com

Macromolecules and Nutrition
 Macro means large
 Macromolecules are large complex
molecules essential for life
 Carbohydrates
 Lipids
 Proteins
 Nucleic Acids
Human Nutrition
 Human Nutrition, study of how food affects the
health and survival of the human body.
 Human beings require food to grow, reproduce, and
maintain good health. Without food, our bodies could
not stay warm, build or repair tissue, or maintain a
heartbeat.
 Eating the right foods can help us avoid certain
diseases or recover faster when illness occurs.
Nutrition: Nutrients
 The importance of a nutrient is judged by how long
we can do without it, water ranks as the most
important.
 A person can survive only eight to ten days
without water, whereas it takes weeks or even
months to die from a lack of food.
Macromolecules: Carbohydrates
Carbohydrates
made of C,H,O
Sugar
Starch
The ratio of hydrogen to oxygen is 2:1
Cellulose
Nutrition: Carbohydrates
 Carbohydrates are the human body’s key source
of energy, providing 4 calories of energy per gram.
 When carbohydrates are broken down by the
body, the sugar glucose is produced; glucose is
critical to help maintain tissue protein, metabolize
fat, and fuel the central nervous system and body
cells.
Nutrition: Carbohydrates
 Glucose is absorbed into the bloodstream
through the intestinal wall.
 Some of this glucose goes straight to work in our
brain cells and red blood cells, while the rest
makes its way to the liver and muscles, where it
is stored as glycogen (animal starch), and to fat
cells, where it is stored as fat.
 Glycogen is the body’s auxiliary energy source,
tapped and converted back into glucose when we
need more energy.
Nutrition: Carbohydrates
 Although stored fat can also serve as a backup
source of energy, it is never converted into
glucose.
 Fructose and galactose, other sugar products
resulting from the breakdown of carbohydrates,
go straight to the liver, where they are converted
into glucose.
Nutrition: Carbohydrates
 Starches and sugars are the major
carbohydrates.
 Common starch foods include whole-grain
breads and cereals, corn, beans, peas, and
potatoes.
 Naturally occurring sugars are found in fruits
and many vegetables; milk products; and honey,
maple sugar, and sugar cane.
Nutrition: Carbohydrates
 Foods that contain starches and naturally occurring
sugars are referred to as complex carbohydrates,
because their molecular complexity requires our
bodies to break them down into a simpler form to
obtain the much-needed fuel, glucose.
 Our bodies digest and absorb complex
carbohydrates at a rate that helps maintain the
healthful levels of glucose already in the blood.
Nutrition: Carbohydrates
 In contrast, simple sugars, refined from naturally
occurring sugars and added to processed foods,
require little digestion and are quickly absorbed by
the body, triggering an unhealthy chain of events.
 The body’s rapid absorption of simple sugars
elevates the levels of glucose in the blood, which
triggers the release of the hormone insulin.
Nutrition: Carbohydrates
 Many processed foods not only contain high levels of
added simple sugars, they also tend to be high in fat
and lacking in the vitamins and minerals found
naturally in complex carbohydrates.
 Nutritionists often refer to such processed foods as
junk foods and say that they provide only empty
calories, meaning they are loaded with calories from
sugars and fats but lack the essential nutrients our
bodies need.
Nutrition: Carbohydrates
 In addition to starches and sugars, complex
carbohydrates contain indigestible dietary fibers.
 Although such fibers provide no energy or building
materials, they play a vital role in our health.
 Found only in plants, dietary fiber is classified as
soluble or insoluble.
Nutrition: Carbohydrates
 Soluble fiber, found in such foods as oats, barley,
beans, peas, apples, strawberries, and citrus fruits,
mixes with food in the stomach and prevents or
reduces the absorption by the small intestine of
potentially dangerous substances from food.
 Soluble fiber also binds dietary cholesterol and
carries it out of the body, thus preventing it from
entering the bloodstream where it can accumulate
in the inner walls of arteries and set the stage for high
blood pressure, heart disease, and strokes.
Nutrition: Carbohydrates
 Insoluble fiber, found in vegetables, whole-grain
products, and bran, provides roughage that speeds
the elimination of feces, which decreases the time
that the body is exposed to harmful substances,
possibly reducing the risk of colon cancer.
 Studies of populations with fiber-rich diets, such as
Africans and Asians, show that these populations have
less risk of colon cancer compared to those who eat
low-fiber diets, such as Americans.
Nutrition: Carbohydrates
 Experts recommend that these foods make up no
more that 10 percent of our diet, because these foods
offer no nutritional value.
 Foods rich in complex carbohydrates, which provide
vitamins, minerals, some protein, and dietary fiber
and are an abundant energy source, should make up
roughly 50 percent of our daily calories.
Nutrition
 When we eat carbohydrates, the molecules
are broken apart to form simple sugars.
 Water must be added for this process to
occur (hydrolysis).
Carbohydrates: Glycogen
 Glycogen is animal starch.
 It is made of highly branched chains of
glucose molecules.
 It is produced in the liver and stored in the
liver and muscles.
 When extra energy is needed, the liver
converts glycogen into glucose.
Polysaccharide: Glycogen
(From an animal)
Carbohydrates: Cellulose
 Cellulose is a large polysaccharide made of
chains of glucose molecules.
 It may contain as many as 3,000 glucose
molecules.
 Cellulose forms a strong fibrous structure in
plant cell walls. It gives the walls support.
Polysaccharide: Cellulose
Nutrition: Lipids
 Fat stored in the body plays a vital role in and
protecting us from extreme cold and heat.
 Fat consists of fatty acids attached to a
substance called glycerol.
 Dietary fats are classified as saturated,
monounsaturated, and polyunsaturated
according to the structure of their fatty acids (see
Fats and Oils).
Nutrition: Lipids
 Fats, which provide 9 calories of energy per gram,
are the most concentrated of the energyproducing nutrients, so our bodies need only
very small amounts.
 Fats play an important role in building the
membranes that surround our cells and in
helping blood to clot.
 Once digested and absorbed, fats help the body
absorb certain vitamins.
Nutrition: Lipids
 Animal fats—from eggs, dairy products, and
meats—are high in saturated fats and cholesterol,
a chemical substance found in all animal fat.
 Vegetable fats—found, for example, in avocados,
olives, some nuts, and certain vegetable oils—are
rich in monounsaturated and polyunsaturated fat.
 As we will see, high intake of saturated fats can be
unhealthy.
Nutrition: Lipids
 To understand the problem with eating too much
saturated fat, we must examine its relationship to
cholesterol.
 High levels of cholesterol in the blood have been
linked to the development of heart disease, strokes,
and other health problems.
 Despite its bad reputation, our bodies need
cholesterol, which is used to build cell membranes,
to protect nerve fibers, and to produce vitamin D
and some hormones, chemical messengers that
help coordinate the body’s functions.
Nutrition: Lipids
 We just do not need cholesterol in our diet. The
liver, and to a lesser extent the small intestine,
manufacture all the cholesterol we require.
 When we eat cholesterol from foods that contain
saturated fatty acids, we increase the level of a
cholesterol-carrying substance in our blood that
harms our health.
Nutrition: Lipids
 Cholesterol, like fat, is a lipid—an organic
compound that is not soluble in water.
 In order to travel through blood, cholesterol
therefore must be transported through the body in
special carriers, called lipoproteins.
 High-density lipoproteins (HDLs) remove
cholesterol from the walls of arteries, return it to the
liver, and help the liver excrete it as bile, a liquid
acid essential to fat digestion.
 For this reason, HDL is called "good" cholesterol.
Nutrition: Lipids
 Low-density lipoproteins (LDLs) and very-lowdensity lipoproteins (VLDLs) are considered
"bad" cholesterol.
 Both LDLs and VLDLs transport cholesterol from
the liver to the cells.
 As they work, LDLs and VLDLs leave plaqueforming cholesterol in the walls of the arteries,
clogging the artery walls and setting the stage for
heart disease.
Nutrition: Lipids
 Almost 70 percent of the cholesterol in our
bodies is carried by LDLs and VLDLs, and the
remainder is transported by HDLs.
 For this reason, we need to consume dietary fats
that increase our HDLs and decrease our LDL
and VLDL levels.
Nutrition: Lipids
 Saturated fatty acids—found in foods ranging from
beef to ice cream, to mozzarella cheese to
doughnuts—should make up no more than 10
percent of a person’s total calorie intake each day.
 Saturated fats are considered harmful to the heart
and blood vessels because they are thought to
increase the level of LDLs and VLDLs and decrease
the levels of HDLs.
Nutrition: Lipids
 Monounsaturated fats—found in olive, canola, and
peanut oils—appear to have the best effect on blood
cholesterol, decreasing the level of LDLs and VLDLs
and increasing the level of HDLs. Polyunsaturated
fats—found in margarine and sunflower, soybean,
corn, and safflower oils—are considered more
healthful than saturated fats.
 However, if consumed in excess (more than 10
percent of daily calories), they can decrease the blood
levels of HDLs.
Nutrition: Lipids
 Most Americans obtain 15 to 50 percent of their daily
calories from fats.
 Health experts consider diets with more than 30
percent of calories from fat to be unsafe, increasing
the risk of heart disease.
 High-fat diets also contribute to obesity, which is
linked to high blood pressure and diabetes mellitus.
Nutrition: Lipids
 A diet high in both saturated and unsaturated fats has
also been associated with greater risk of developing
cancers of the colon, prostate, breast, and uterus.
 Choosing a diet that is low in fat and cholesterol is
critical to maintaining health and reducing the risk of
life-threatening disease.

"Human Nutrition," Microsoft® Encarta® Encyclopedia 99. ©
1993-1998 Microsoft Corporation. All rights reserved.
Macromolecules: Lipids
 Lipids are macromolecules made of carbon,
hydrogen, and oxygen.
 The ratio of hydrogen to oxygen is much
greater than 2:1.
 Lipids are made of fatty acids attached to
alcohol.
 Examples: fats, oil, waxes and cholesterol.
Nutrition: Proteins
 Dietary proteins are powerful compounds that build
and repair body tissues, from hair and fingernails to
muscles.
 In addition to maintaining the body’s structure,
proteins speed up chemical reactions in the body,
serve as chemical messengers, fight infection, and
transport oxygen from the lungs to the body’s tissues.
Nutrition: Proteins
 Although protein provides 4 calories of energy per
gram, the body uses protein for energy only if
carbohydrate and fat intake is insufficient.
 When tapped as an energy source, protein is
diverted from the many critical functions it performs
for our bodies.
Nutrition: Proteins
 Proteins are made of smaller units called amino
acids.
 Of the more than 20 amino acids our bodies require,
eight (nine in some older adults and young children)
cannot be made by the body in sufficient quantities to
maintain health.
 These amino acids are considered essential and
must be obtained from food.
Nutrition: Proteins
 When we eat food high in proteins, the digestive tract
breaks this dietary protein into amino acids.
 Absorbed into the bloodstream and sent to the cells
that need them, amino acids then recombine into the
functional proteins our bodies need.
PROTEINS
•In plant foods- in the cell membranes
•In animal products- in the cell
membranes- in the muscles or living
things- cows, chicken, fish…
Proteins
Proteins
Aside from the protein found in animal
sources…protein can also be found in fruits,
vegetables, grains, and nuts. (it just does not have as
many amino acids)
Nutrition: Proteins
 Animal proteins, found in such food as eggs, milk,
meat, fish, and poultry, are considered complete
proteins because they contain all of the essential
amino acids our bodies need.
 Plant proteins, found in vegetables, grains, and
beans, lack one or more of the essential amino acids.
 However, plant proteins can be combined in the diet
to provide all of the essential amino acids.
Nutrition: Proteins
 A good example is rice and beans.
 Each of these foods lacks one or more essential
amino acids, but the amino acids missing in rice are
found in the beans, and vice versa. So when eaten
together, these foods provide a complete source of
protein.
 Thus, people who eat only vegetables (see
Vegetarianism) can meet their protein needs with
diets rich in grains, dried peas and beans, rice, nuts,
and tofu, a soybean product.
Nutrition: Proteins
 Experts recommend that protein intake make up only
10 percent of our daily calorie intake.
 Some people, especially in the United States and
other developed countries, consume more protein
than the body needs.
 Because extra amino acids cannot be stored for later
use, the body destroys these amino acids and
excretes their by-products.
Nutrition: Proteins
 Alternatively, deficiencies in protein consumption,
seen in the diets of people in some developing
nations, may result in health problems.
 Marasmus and kwashiorkor, both life-threatening
conditions, are the two most common forms of
protein malnutrition.
Nutrition: Proteins
 Some health conditions, such as illness, stress, and
pregnancy and breast-feeding in women, place an
enormous demand on the body as it builds tissue or
fights infection, and these conditions require an
increase in protein consumption.
 For example, a healthy woman normally needs 45
grams of protein each day.
 Experts recommend that a pregnant woman consume
55 grams of protein per day, and that a breast-feeding
mother consume 65 grams to maintain health.
Nutrition: Proteins
 A man of average size should eat 57 grams of protein
daily.
 To support their rapid development, infants and
young children require relatively more protein than do
adults.
 A three-month-old infant requires about 13 grams of
protein daily, and a four-year-old child requires about
22 grams.
Nutrition: Proteins
 Once in adolescence, sex hormone differences
cause boys to develop more muscle and bone than
girls; as a result, the protein needs of adolescent
boys are higher than those of girls.

"Human Nutrition," Microsoft® Encarta® Encyclopedia 99. ©
1993-1998 Microsoft Corporation. All rights reserved
Macromolecules: Proteins
 Proteins are the most common organic
molecule in living cells.
 They are made of carbon, hydrogen,
oxygen, nitrogen and sometimes sulfer.
CHON(S)
 Proteins are made of amino acids. There
are approximately 20+ amino acids.
Macromolecules: Proteins
Proteins are large complex polypeptides.
Prentice Hall,
Biology
Think of the amino acids as letters and proteins as words in
making up a sentence.
Proteins may contain as few as 50 or as many as 3,000 amino
acid molecules. The number of possible combinations of amino
acids is staggering. We have tens of thousands of different
proteins.
Macromolecules: Proteins
 Amino acids are joined by means of dehydration synthesis.

An OH from the acid group of one amino acid joins to
an H from the amino group of the other amino acid.
 A water molecule is formed, and a C-N bond is formed
between the two amino acids.
 The C-N bond is called a peptide bind.
 Dipeptide: 2 amino acids joined
 Polypeptide: 3 or more amino acids joined.
Proteins
 Composed of amino acids
 Amino acids are joined by peptide
bonds
 The string of peptides is also called
a polypeptide
 Needed for muscles, skin, cell
membranes, and enzymes
Proteins: Structure
 Amino acids have three parts:
 The 20+ amino acids differ only in their R-group
Generalized Formula for Amino Acid
H
R
C
Acid group
COOH
NH2
Rest of the molecule
Amino group
Macromolecules: Proteins
 Proteins taken in as food are different than our proteins.
 They must be broken down into amino acids by adding
water. Recall Carbohydrates and Lipids
 The process is…
 Hydrolysis.
 To build proteins water must be removed in the process
of….
 Dehydration Synthesis.
Proteins: Structure
 Compare 3 amino acids:
Proteins: Enzymes
 Enzyme, any one of many specialized organic
substances, composed of polymers of amino acids,
that act as catalysts to regulate the speed of the many
chemical reactions involved in the metabolism of living
organisms.
 Those enzymes identified now number more than 700.
Substrate: The substance that the enzyme causes to react.
Enzymes
The 4th type of biochemical
macromolecules are the
NUCLEIC ACIDS
The types of Nucleic Acids
 DNA (DeoxyriboNucleic Acid)
 RNA (RiboNucleic Acid)