Structural View of Biology
Health and Disease
Biomolecular structures allow us to understand the molecular nature of healthy cells and treat the underlying molecular causes of disease. Our cells contain thousands of molecules that must all work in concert to keep us healthy. When any of these molecules fails, or when a poison or pathogenic organism attacks these molecules, it may cause disease. Our bodies have many defenses against disease, and medical science has developed powerful drugs to assist these defenses.
Vitamins and Minerals
Vitamins and minerals are molecules that are essential for good health, and must be obtained in our diet. They are used in cells to build molecular tools for performing specialized tasks. Most often, our cells cannot build these molecules from scratch, so we must get them in our food. If we don't have them in our diet, it can lead to diseases like scurvy.
Scroll to a Molecule of the Month Feature in this subcategory:
Eat your carrots or you'll go blind! The biochemical reason for this childhood warning is that we need retinal, vitamin A, to form the pigment that absorbs light in our eyes. Unfortunately, our cells cannot make it for themselves, so we have to obtain it in our diet. We typically get our daily dose of vitamin A in two different ways. Retinal, or molecules similar to it, may be obtained directly when we eat meat. Alternatively, we can eat molecules that are easily transformed into retinal. This is where the carrots enter the story. They are full of beta-carotene, which our cells break in half to form two molecules of retinal.
Inside cells, extra iron ions are locked safely in the protein shell of ferritin, shown here from PDB entry 1fha. Ferritin is composed of 24 identical protein subunits that form a hollow shell. The bottom illustration shows the hollow shell cut in half, showing the chamber inside and a few of the pores that lead inside the shell. After entering the ferritin shell, iron ions are converted into the ferric state, where they form small crystallites along with phosphate and hydroxide ions. There is room to pack about 4500 iron ions inside.
Vitamins are exotic molecules that are essential for the proper function of cells, but somewhere along the process of evolution, our bodies have lost the ability to make them. So instead, we need to obtain them in our diet, or in a daily multivitamin tablet. These include vitamin A, which is used to build the light sensors in our eyes, a host of B vitamins used to build specialized tools for chemical reactions, and vitamin C, which plays an essential role in construction of collagen. Vitamin D is an exceptional case: our cells can make it, but only if there is enough sunlight.
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