So why chemistry in a biology specialization? When I was in college, my general chemistry professor described chemistry as a central science. It's important not only for its own sake, but for the study of biology and for physics as well. So what does chemistry have to do with biology? Well, in the most basic terms, you are chemistry. We are living, walking, breathing, talking water-based or aqueous chemical reactions. The light you see from your computer screen right now is interpreted by your brain and through a series of chemical reactions. Your ability to move, again, chemical reactions, digesting your food, all chemical reactions. I promise you won't have to memorize elements of the periodic table as part of this specialization. Instead, let's talk about chemistry as it relates to our daily lives. In particular, let's talk about chemicals. We hear bad things about chemicals all the time in society, about keeping chemicals out of our homes and out of our bodies. But what is a chemical? The Cambridge Dictionary defines chemicals as basic substances that are used in or produced by a reaction involving changes to atoms or molecules. Or as an adjective, it is, of, involved with, relating to, or made by using chemicals or chemistry. So are chemicals bad? Well, let's zoom in on one chemical, dihydrogen monoxide. It's found in 100% of people who die of cancer. It can cause serious damage to your car. And if you're like me and you live in a dry climate, your monthly dihydrogen monoxide bill can leave you a little bit faint of heart. Have you heard that one before? What is dihydrogen monoxide? Well, let's break it down. Di means two and a hydrogen is an element. So dihydrogen means two hydrogens. Mono means one and oxide refers to oxygen. So monoxide means one oxygen. Dihydrogen monoxide is something with two hydrogens and one oxygen, also known as H20 or our good friend water. Life as we know it requires water. This is why the search for extraterrestrial life often revolves around the search for water. Although we may take water for granted, it is a very unique chemical. It is the only chemical that exists as a gas, liquid, and solid naturally on Earth. Because of its molecular shape or structure, it's got a little bit of a V shape to it. With the positive hydrogens on one end and the negative oxygens on the other, it can form what are called hydrogen bonds. Opposites attract, so the negative and positive ends of water will attract to one another and form weak connections or bonds called hydrogen bonds. On their own, hydrogen bonds aren't very strong, but together they are very strong. Think of it like Velcro. The individual connections on Velcro aren't very strong. But when you put all of those connections together, you have something quite strong. So for example, the eerie sheen that we can see in a swimmer right before they break the surface of the water is caused by hydrogen bonding within the water. Because the water is linked together, it creates what's called surface tension. And those water molecules hooked together is why you see that weird sheen. Surface tension is also what allows insects like water striders to skate along the surface of the water. Have you ever accidentally done a belly flop before? The reason it hurts is because the surface tension of the water is so strong that landing like that is equivalent to hitting something that's completely solid. This is also why at professional diving competitions, there's sprinklers running immediately below the diving platforms to break up the surface tension and prevent injury to the divers. Hydrogen bonding also explains some of water's stickiness. For example, water can stick to itself and also to other surfaces. Cohesion, or its ability to stick to itself, and adhesion, its ability to stick to something else, explains how water can climb from the roots of trees to the very tops of the leaves. Another interesting property of water as it relates to life is its ability to insulate. If you happen to live near a body of water, you'll know that it tends to stay warmer or cooler longer as the seasons change. This is because water is really good at resisting temperature changes. So it's also why hot water heat is a more efficient way of heating your home as well. Water holds on to heat better than air, therefore allowing you to heat your house more efficiently. Also one of the reasons that we sweat when we're hot is to help dissipate heat. That heat leaves our body as part of those water droplets on our skin. Water is also very unique in that it expands when frozen, and it's also less dense when frozen. These properties, combined with its insulating ability, explains why animals can live at the bottom of the ponds all winter long. The frozen water or ice forms a cap that floats on the surface of the pond and acts as an insulating barrier to keep the critters down below warm. So is water okay then because it's a natural chemical? Are natural chemicals better than synthetic chemicals? What do you think?
