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 also the building blocks of life. Our muscle cells, for example contain a lot of protein. Proteins are also used by the cell to package the DNA into compact structures called chromosomes.Proteins are used by organisms to make such things like hair, nails, rhino horns, feathers, scales, the beaks of birds, and procupine quills, among other things. Source(s):roteins have nitrogen, oxygen, hydrogen, and carbon. The use of a protein is to grow and repair the body. It is also used to create enzymes.