One of the most common nutrients for the body is protein. Proteins are long chains of amino acids, which includes the elements of carbon, hydrogen, oxygen, and nitrogen. There are twenty different kinds of amino acids that combine to make proteins in the body. A person's body can make some amino acids, but like the other two macronutrients, carbohydrates and fats, proteins are obtained from food.

There are thousands of different proteins in the body and each has functions to help keep the body healthy. They are essential for life, and around 20% of the body is made up of proteins, and every cell in the body uses proteins to perform functions.

A few of the major groups and functions of proteins include the following:

. Structural: Proteins that provide structure for the body and includes collagen which is found in cartilage and tendons.

. Defensive: Proteins that help protect the body from diseases, and they make up antibodies that fight off foreign germs such as bacteria and other toxic substances.

. Transport: Proteins that carry essential nutrients around the body. Such as hemoglobin which carries oxygen in the red blood cells.

. Catalysts: Some of the proteins, called enzymes, act as catalysts to assist in chemical reactions, and they help break up and digest food, so it can be used by the cells in the body.

The best sources of protein are beef, poultry, eggs, fish, nuts, seeds, legumes, and dairy products. Protein builds, maintains, and replaces the tissues in the body. In fact, the muscles, organs, and the immune system are mostly made up of protein.

When a person eats foods that contain protein, the digestive juices in the stomach break down the protein in food into amino acids, which then can be reused to make the proteins the body needs to maintain body organs, muscles, blood, and bones.

The proteins in the body are sometimes described as long necklaces with a variety of shaped beads, and each bead is a small amino acid. They join to make thousands of different proteins, and scientists have found many different amino acids. However, only about 22 of them are very important to the health of the body.

The protein that comes from animal sources such as meat and milk is called complete because it contains all nine of the essential amino acids. Vegetable protein is considered incomplete because it does not have one or more of the essential amino acids, which can be a problem for people who do not eat animal products. However, there are some protein-rich vegetable foods. For example, a person cannot get all their amino acids from peanuts alone, but peanut butter on whole-grain bread has the protein that is needed.

Finally, the amount of food from the different Protein Foods Group depends on a person's age, sex, and level of physical activity. For example, about 0.5 grams of protein is needed for every pound a child weighs. As a person gets older, the amount of protein needed will increase.

In summary, protein is one of the three macronutrients a person's body needs for good health, along with carbohydrates and fats.

A: Vitamins
B: Proteins
C: Fats
D: Carbohydrates

A: Structural
B: Defensive
C: Transport
D: Catalysts

A: Structural
B: Defensive
C: Transport
D: Catalysts

A: Hemoglobin
B: Amino acid
C: Enzymes
D: Fats

A: Poultry and eggs
B: Beef and fish
C: Nuts and dairy products
D: Fruit and vegetables

A: 50 grams
B: 25 grams
C: 5 grams
D: 125 grams

Related Topics
Proteins Quiz
Proteins Examples
Proteins Quiz
Function of Ribosomes
Function of Nucleolus
The Function of Endoplasmic Reticulum
The Function Of a Cytoskeleton
Metabolism Quiz
The Function Of Golgi Apparatus
Frederick Sanger Facts

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