Proteins
There are over 10,000 different proteins in the body
Examples:
Groups: red meats, poultry, fish, eggs, nuts, seeds, cheese, yogurt and beans
Turkey breast
Chicken breast
Fish
Cheese (non-fat mozzarella)
Pork loin
Lean beef
Beans (Mature soy beans)
Eggs
Yogurt
Milk
Nuts and seeds

Importance of proteins:
We break down proteins into their amino acid components and then rebuild them into our body proteins, which is called protein digestion and then protein synthesis.
Proteins have specific roles in the body, some proteins are involved in structural support, while others are involved in bodily movement, or in defence against germs. For example;
Antibodies defend the body from germs
Contractile proteins are responsible for movement
Storage proteins store amino acids
Enzymes speed up chemical reactions

Sporting examples of use of proteins:
Athletes need protein primarily to repair and rebuild muscle that is broken down during exercise and to help optimizes carbohydrate storage in the form of glycogen. Protein isn’t an ideal source of fuel for exercise, but can be used when the diet lacks adequate carbohydrate. This is detrimental, though, because if used for fuel, there isn’t enough available to repair and rebuild body tissues, including muscle.
Recommended Daly Protein Intake:
The average adult needs 0.8 grams per kilogram (2.2lbs) of body weight per day.
Strength training athletes need about 1.4 to 1.8 grams per kilogram (2.2lbs) of body weight per day
Endurance athletes need about 1.2 to 1.4 grams per kilogram (2.2lbs) of body weight per day
Food, Amount, Protein:

Fish, 3 oz, 21 grams
Chicken, 3 oz, 21 grams
Turkey, 3 oz, 21 grams
Beef, 3 oz, 21 grams
Milk, 8 oz, 8 grams