Organic Molecules in Nutrition
Why do you eat?
While eating cereal for breakfast, you’ve probably read all the ads and offers on
the box. You may also have noticed the list of nutrients on the side panel. By law, the
amount of each nutrient in the cereal had to be listed for you on the label. You think
you’re eating toasted corn with raisins, but you’re really taking in nutrients. Nutrients
are substances in foods that provide energy and materials for cell development, growth
and repair.
There are six kinds of nutrients in food: carbohydrates, proteins, fats, vitamins,
minerals and water. Carbohydrates, proteins, vitamins, and fats are all organic nutrients.
In contrast, minerals and water are inorganic. They do not contain carbon. Foods
containing carbohydrates, fats, and proteins are usually too complex for to be absorbed
right away by your body. These substances need to be broken down into simpler
molecules before the body can make use of them. IN contrast, minerals and water can be
absorbed directly into your bloodstream. They don’t require digestion or breakdown.
Carbohydrates
If you look at the panels on several boxes of cereal, you’ll notice that
carbohydrates are frequently listed first. That means that most of the nutrient in that
particular cereal is in carbohydrate form. Carbohydrates are the main source of energy
for your body. They contain carbon, hydrogen, and oxygen atoms. During respiration,
energy is released when molecules of carbohydrate break down in your cells. Starch,
cellulose, and sugar are three types of carbohydrates. Starch is in foods such as potatoes
and those made from grains such as pasta. Cellulose occurs in plant cell walls. There are
many types of sugars. You’re probably most familiar with the one called table sugar.
Table sugar is an example of a simple carbohydrate. Fruits, honey and milk are all
sources of sugar. Your cells use sugar in the form of glucose.
Proteins
Proteins are nutrients needed throughout your body for growth, as enzymes, and
in the replacement and repair of body cells. Proteins are large molecules that contain
carbon, hydrogen, oxygen, and nitrogen. A molecule of protein is made up of a large
number of subunits or building blocks called amino acids. Proteins are made according
to directions supplied by genes that you inherit. Your body needs 20 different amino
acids to be able to construct the proteins needed in your cells. Most of these amino acids
can be made in your cells. The eight remaining amino acids are called essential amino
acids. Your body doesn’t have genetic instructions to construct them in your cells.
Therefore, they have to be supplied through food in your diet. Eggs, milk, and cheese
contain all the essential amino acids. Beef, pork, fish, chicken, and nuts supply some of
them. You might be surprised to know that whole grains such as wheat, rice and
soybeans supply many needed amino acids in addition to carbohydrates.
Fats
Fats, or lipids, are nutrients that provide energy and help your body store some
vitamins. For good health, your diet should be no more than 30 percent fat. Fats are
stored in your body in the form of fat tissue that cushions your internal organs.
Carbohydrates supply most people with most of the energy they need, because most
people eat a lot of carbohydrates. A single molecule of fat breaks down into smaller
molecules called fatty acids and glycerol.
There are two types of fats: Unsaturated and saturated fats. Plants supply
unsaturated fats. Corn, safflower, and soybean oils are all unsaturated fats. Some
unsaturated fats are also found in poultry, fish, and nuts. Saturated fats are found in red
meats. Saturated fats have been associated with high levels of blood cholesterol that
contribute to heart disease. A lot has been written about the bad effects of cholesterol.
However, cholesterol does occur normally in all your cell membranes. But, too much
cholesterol in your diet causes fat deposits to form on the walls of blood vessels, resulting
in a cutoff of blood supply to organs and an increase in blood pressure.
Fat
Breaks down into
Fatty acids and
glycerol
May be
Saturated
Unsaturated
from
from
Animals
Plants
Vitamins
Vitamins are essential, organic nutrients needed in small quantities to help your
body use other nutrients. For instance, Vitamin D is needed for bone cells to use the
mineral calcium. In general, vitamins promote growth and regulate many body functions.
Most foods supply some vitamins, but no one food has them all. Eating a variety
of foods usually supplies all the vitamins a body needs. Some vitamins dissolve easily in
water and are called water-soluble vitamins. Others dissolve only in fat and are called
fat-soluble vitamins. Although some people feel that taking extra vitamins is helpful,
normally eating a balanced diet is sufficient to give your body all the vitamins it needs.
Vitamins are found in a variety of meats and vegetables. Your body makes vitamin D
when your sun is exposed to sunlight. Some vitamin K is made with the help of bacteria
that live in your large intestine.
Fill in the following chart from your reading:
Organic
nutrient
Purpose/Use
Building block Atoms involved
Source
Examples
Answer Key
Organic
nutrient
Carbohydrate
Proteins
Fats (lipids)
Vitamins
Purpose /Use
Energy
Growth,
replacement
and repair of
body cells
Energy, store
vitamins
Building block
Atoms involved
Sugar
Carbon
Hydrogen
Oxygen
Amino Acids
Fatty acids and
glycerol
Help your body
use other
NA
nutrients
Carbon
Hydrogen
Oxygen
Nitrogen
(Carbon
Hydrogen
Oxygen) info
not in reading
NA
Source
Examples
Foods such as
potatoes and
pasta
Also plant cell
walls
Starch
Cellulose
Sugar
Meats, egg,
milk, cheese
NA
Meats and
plants
Corn oil,
soybean oil
Meats and
vegetables
Vitamin D
Vitamin K