Identifying macromolecules

Macromolecules can be found EVERYWHERE! In fact, you probably ate some last night or this morning! There are 4 main macromolecules (carbohydrates, lipids, proteins, and nucleic acids). In this webquest you will investigate the properties of 3 of those macromolecules and how to run scientific tests to find them. You will be working as an investigator to use your knowledge to solve a mystery!

 

Macromolecules are identified in all the processed foods you eat, this information is given in the food labels, just like the one shown bellow.

 

Get Your Nutrition Facts Straight

The Nutrition Facts food label gives you information about which nutrients (say: NEW-tree-ents) are in the food. Your body needs the right combination of nutrients, such as vitamins, to work properly and grow.

The Nutrition Facts food label is printed somewhere on the outside of packaged food, and you usually don't have to look hard to find it. Fresh food that doesn't come prepackaged sometimes has nutrition facts, too.

Most nutrients are measured in grams, also written as g. Some nutrients are measured in milligrams, or mg. Milligrams are very tiny — there are 1,000 milligrams in 1 gram.

Other information on the label is given in percentages. Food contains fat, protein, carbohydrates, and fiber. Food also contains vitamins, such as A and C, and minerals, such as calcium and iron. Nutrition specialists know how much of each one kids and adults should get every day to have a healthy diet. The percent daily value on a food label tells you how this food can help someone meet these daily goals.

On food labels, they base the percentages on a 2,000-calorie adult diet. So looking at the label above for two crackers, a grownup would see that they provide less than 1 gram of fiber, only 3% of the person's daily needs. So that means he or she would have to eat other foods to get 100% of the fiber needed each day. Similarly, the person would see that the crackers provide nothing toward the daily goals for vitamin A, vitamin C, calcium, or iron.

Serving Size

The nutrition label always lists a serving size, which is an amount of food, such as 1 cup of cereal, two cookies, or five pretzels. The nutrition label tells you how many nutrients are in that amount of food.

Serving sizes also help people understand how much they're eating. If you ate 10 pretzels, that would be two servings.

Servings per Container or Package

The label also tells you how many servings are contained in that package of food. If there are 15 servings in a box of cookies and each serving is two cookies, you have enough for all 30 kids in your class to have one cookie each. Math comes in handy with food labels!

Calories and Calories From Fat

The number of calories in a single serving of the food is listed on the left of the label. This number tells you the amount of energy in the food. The calories in a food can come from fat, protein, or carbohydrate. People pay attention to calories because if you eat more calories than your body uses, you will gain weight.

Another important part of the label is the number of calories that come from fat. People check this because it's good to limit fat intake to about 30% or less of the calories they eat.

Total Fat

The total fat is the number of fat grams contained in one serving of the food. Fat is an important nutrient that your body uses for growth and development, but you don't want to eat too much. The different kinds of fat, such as saturated, unsaturated, and trans fat, will be listed separately on the label.

Cholesterol and Sodium

These numbers tell you how much cholesterol and sodium (salt) are in a single serving of the food. They are included on the label because some people should limit the amount of cholesterol and salt in their diets. Cholesterol and sodium are usually measured in milligrams.

Total Carbohydrate

This number tells you how many carbohydrate grams are in one serving of food. Carbohydrates are your body's primary source of energy. This total is broken down into grams of sugar and grams of dietary fiber.

Protein

This number tells you how much protein you get from a single serving of the food. Your body needs protein to build and repair essential parts of the body, such as muscles, blood, and organs. Protein is often measured in grams.

Vitamin A and Vitamin C

These list the amounts of vitamin A and vitamin C, two important vitamins, in a serving of the food. Each amount is given as a percent daily value. Other vitamins may be listed on some labels.

Calcium and Iron

These list the percentages of calcium and iron, two important minerals, that are in a serving of the food. Again, each amount is given as a percent daily value and other minerals may be listed on the label.

Calories per Gram

These numbers show how many calories are in one gram of fat, carbohydrate, and protein. This information is the same for every food and is printed on the food label for reference.

Now that you know a little more about food labels, you can read up on what you're eating!