Avoiding Surcharges. Because airlines charge a peak travel day surcharge on the most popular days of travel -- Sunday, Monday and Friday -- you can get the best discounts on those off-peak days. However, during the summer, peak and off-peak travel days do not really exist.
Proteins are essential nutrients for the human body. They are one of the building blocks of body tissue, and can also serve as a fuel source. As a fuel, proteins contain 4 kcal per gram, just like carbohydrates and unlike lipids, which contain 9 kcal per gram.
Proteins are very important molecules in our cells. They are involved in virtually all cell functions. Each protein within the body has a specific function. Some proteins are involved in structural support, while others are involved in bodily movement, or in defense against germs. Proteins vary in structure as well as function. They are constructed from a set of 20 amino acids and have distinct three-dimensional shapes. Below is a list of several types of proteins and their functions.