Steroids are synthesized from cholesterol, and all have almost the same molecular structure. We need everyday 350 mg of cholesterol, and if not supplied, the liver produces it. One egg contains more than enough cholesterol for the day. We should be aware of the bad effects of cholesterol because if we have more in the blood, it starts to clog the arteries and cause heart failure, or not enough blood to the brain which can then lead to a stroke. To avoid this effect, one should not consume lot of animal fat, and exercise daily to reverse the cholesterol level in the blood.
Proteins are polymers of amino acids.
In the diagram, a peptide amino acid is represented. Protein is the building block of animals and humans. We need the essential amino acids which are the bulding blocks of protein. There are 22 amino acids in which 8 are essentials and if not supplied, the body cannot produce the rest. Never should a meal be consumed without protein.