Food Macromolecules
• Macromolecules are large complex molecules
essential for life
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids
Lipids
Carbohydrates
Macromolecules
Proteins
Nucleic Acids
Human Nutrition
• These and other important functions are fueled by
chemical substances in our food called nutrients.
•
Nutrients are classified as carbohydrates, proteins,
fats, vitamins, minerals, and water.
• When we eat a meal, nutrients are released from
food through digestion.
Human Nutrition: Digestion
• Nutrients are absorbed from the inside of the small
intestine into the bloodstream and carried to the
sites in the body where they are needed.
• At these sites, several chemical reactions occur that
ensure the growth and function of body tissues.
• The parts of foods that are not absorbed continue to
move down the intestinal tract and are eliminated
from the body as feces.
Human Nutrition: Digestion
• Once digested, carbohydrates, proteins, and fats
provide the body with the energy it needs to
maintain its many functions.
•
Scientists measure this energy in kilocalories, the
amount of energy needed to raise 1 kilogram of water 1
degree Celsius.
• The term calorie instead of kilocalorie is the standard
unit of measure in nutrition.
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.
Carbohydrates
• Starches and sugars are the major carbohydrates.
•
Common starch foods include whole-grain breads
and cereals, pasta, corn, beans, peas, and potatoes.
•
Naturally occurring sugars are found in fruits and
many vegetables; milk products; and honey, maple
sugar, and sugar cane.
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.
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.
Macromolecules: Carbohydrates
Carbohydrates
made of C,H,O
Sugar
Starch
The ratio of hydrogen to oxygen is 2:1
Cellulose
Carbohydrates
Sugar- manufactured in green plants.
Provides the basic fuel for both plant
and animal life.
Carbohydrates
Sugar
Monosaccharides
Mono = one
saccharide = sugar
Disaccharide
Di = two
Polysaccharide
Poly = many
Carbohydrates
Sugar
Monosaccharides- simple sugars that may contain 5 or 6
carbon atoms. Examples: Glucose, Fructose, Galactose
These simple sugars are made in plant cells. They have the
same empirical or molecular formula: C6 H12 O6.
Their structural formulas are different.
Monosaccharides
Monosaccharides
Glucose
Fructose
Galactose
Monosaccharides
Structural formulas of the molecules.
Notice, even though these molecules all have the same number
of each atom, they look different.
Disaccharides
Di = two
Two simple sugars form one molecule of a double sugar. One molecule of water is given off. This
is called a dehydration synthesis reaction.
Disaccharides
Maltose
Sucrose
Lactose
Disaccharides
Glucose + glucose
C6H12O6 + C6H12O6
maltose + water
C12H22O11 + H2O
Dehydration synthesis- take away water to put a molecule together
Disaccharides
Dehydration synthesis- take away water to put a molecule together
Glucose + fructose
sucrose + water
C6H12O6 + C6H12O6
C12H22O11 + H2O
Sucrose is common table sugar. It is found in sugar cane and
sugar beets.
Disaccharides
Dehydration synthesis- take away water to put a molecule together
Glucose + galactose
C6H12O6 + C6H12O6
lactose + water
C12H22O11 + H2O
Lactose is milk sugar, found in the milk of mammals.
Disaccharides
This is an example of Hydrolysis. Water is added to maltose in
order to break it down into two glucose molecules. Of course,
enzymes would control this process.
Hydrolysis
Hydrolysis
Polysaccharides
Polysaccharides are large molecules formed by
joining monosaccharides.
Carbohydrates: Starch
• Starch is a polysaccharide made up of glucose
units in branched chains.
• Each time a glucose molecule is added, one
water molecule is removed (dehydration
synthesis).
• There may be 500 to many thousands of glucose
molecules joined to form a starch molecule.
• Examples: potatoes,corn, rice, wheat, and other
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
Starch
Cellulose
Glycogen
Carbohydrates
(C,H,O)
1
Sugar
Monosaccharide
Glucose
3+
Polysaccharide
Galactose
Fructose
2
Disaccharide
Lactose
Maltose
Sucrose
Compare and Contrast
Starch
Plants
Glycogen
Stored for later,
converted into
glucose for
respiration..
Branched chains
of glucose
Big
Animals
Compare and Contrast
Starch
Branched chains
Stored for later,
converted into
glucose for
respiration.
Cellulose
Carbohydrates
Polysaccharides
glucose
Big
Straight Chains
Found in plant
cell walls
Used for support