When asked what carbohydrates are, most people reply that they are substances for energy. Others reply that carbohydrates are sugars. Both groups are actually partially correct. Carbohydrates, provide much of the energy in the average individuals diet. But energy is not the only function of these exciting little molecules. Carbohydrates perform a number of life-depending functions. Structural roles in various tissues, proper functioning of the immune system, cell production, and recognition are just some of the roles of the carbohydrate. And there are many different carbohydrates to talk about-each having their own special characteristics. Improving mental function, gaining strength, becoming leaner, living longer, modifying disease, preventing disease,and achieving many other goals can be attained by what you know about carbohydrates and the other nutrients that we will elaborate upon.
So, thus far, we can see that the carbohydrate is not just one substance, but rather an "umbrella term", denoting many different molecules. Before discussing many of the properties of carbohydrates and types, you'll find a simple chemistry review below. This review is intended to give those, who are unfamiliar with the chemical world, a little insight into the background of carbohydrates and other chemicals.
We are but chemicals
Everything on this planet is composed of atoms. You, every other person and animal, your car, bicycle, plants, water, the air we breath-all of these are composed of tiny little elements called atoms. A bar of pure gold is composed of atoms of gold. Common table salt is composed of an atom of sodium and an atom of chlorine.
The atom is the smallest piece or building block of an object, that still retains its properties (color, weight, melting point, etc.). The gas, helium floats because of its properties (weight, boiling point, etc.). Gold is malleable (you can bite down on a gold nugget to test if it's genuine and you will see teeth marks in it), and conducts electricity. If you were to divide a bar of gold into smaller and smaller pieces, eventually, you would only have one atom of gold, so small, the most powerful optical microscope couldn't even begin to see. This single atom of gold has all the same properties of the original gold bar-the same melting point, boiling point, metallic properties, etc. And this is the case, with every other type of atom (silver, sodium, carbon, etc.). There are subtle differences in some atoms that are not relevant (except to those in Star Trek, the laboratory, and in science class, so I'll spare you the anti-insomniac details). However, if you absolutely insist on being a "clever-clogs", you can click here
to find out. After all, I wouldn't want to be accused of intellectual neglect :o)
Just as gold is a particular type of atom with its own special set of properties, there are 91 other naturally occuring types of atoms in nature. Including gold, there are 92 types is all. Each one of these types of atoms is called an element. And everything on this planet is made of just these 92 different types of building blocks we call elements, or atoms. How could this be? There are so many differnt materials, colours, smells, tastes in this world, surely more than 92 ! You would be correct in saying this. The reason for such diversity on this planet is because of the way different elements are combined. Each element has its own name and different elements can be combined to make new substances called molecules. A molecule is what we get when we combine 2 or more atoms in combination with each other. For example, we stated that common table salt is composed of one atom of sodium and one atom of chlorine. This can be written in shorthand as:
1Na + 1Cl -----> 1NaCl
This simply means that 1 atom of sodium (Na) added to 1 atom of chlorine (Cl) gives us 1 molecule of table salt (sodium chloride, abbreviated, NaCl). The illustration below demonstrates the simple structural formula of the NaCl molecule.
This is a simple structural representation of sodium chloride. The benefit of this chemical bonding between the atom of sodium and chlorine, is now that they are together, their properties change. For example, chlorine by itself (before it is combined with sodium), is actually a poisonous gas! When it combines with sodium, it loses this property. Now, the sodium chloride (table salt) has its own unique set of properties, and effects on us ! Salt, as we may know is essential in our diet for contributing to normal blood pressure , conduction of nervous impulses, and other functions. However, too much can cause hypertension (above normal blood pressure) as well. Salt (sodium chloride) can also be disassembled back into separate sodium and chlorine atoms. This is the rule with any molecule. If if can be built, it can be taken apart. And this is essential to life, since we rely on disassembling molecules so that we can use their components as building blocks for our body. Furthermore, when certain molecules are broken apart, they release energy. This energy can be used for many things in our body, such as heat, motion, builing new molecules, etc. The list just goes on and on...
Every thing on the planet is composed of either single elements, to combinations of 2 or more, of the 92 naturally occuring elements. Since there are almost an infinite number of combinations, you can imagine how complex some molecules can be. Most of your automobile, may be made from atoms of iron (Fe), lead (Pb), aluminum (Al), carbon (C). These are elements that are classed as metals. Metals are merely atoms that have certain chemical properties (metallic character) and physical properties (they conduct electricity). Did you know that sodium in common table salt is a metal? But remember, once sodium combined with another element, its properties changed.
The carbon (C) atoms that you find in your automobile (or bicycle), are just like the carbon atoms found in your body. That's right, any of the elements in anything are interchangeable with the atoms that we are made of. Essentially, we are made of all the atoms that come from the ground, air and water around us.
You are from dust, and to just you shall return..
Hmmm, there is truth to this saying after all. Now that we have learned a few facts we can begin to discuss carbohydrates. Since we know already that elements are combined to make molecules, how do we group them? We need a type of system that helps us to remember all the different types, don't we? Well, we have a system which makes it easy to group all different combinations together. What we look for is "sets" or "patterns" of atoms linked together. For example, NaCl (salt), is a common pattern in nature. It also has certain characteristics. We group NaCl in the "salt" group. There are many different types of salts. You've already learned about the most common salt, NaCl. Instead of initially combining sodium with chloring, we could have alternatively combined a potassium (K) atom with the chlorine. This is also a salt, and is called potassium chloride (abbreviated, KCl).
Defining the carbohydrate
Let us consider the group of molecules we call carbohydrates. Carbohydrates follow a set of structural patterns, just as the salts we discussed above. Carbohydrates on the other hand, are composed of the atoms carbon (C), hydrogen (H), and oxygen (O). The carbon, hydrogen and oxygen are arranged in a typical pattern for all carbohydrates. All carbohydrates follow this pattern, so you will always be able to identify one when you see its structure. And remember, just as there are different types of salts, there are also different types of carbohydrates. Therefore, we can see how this classification is useful. Classing molecules, enables us to easily group them for convenience.
Now that we know carbohydrates are composed of carbon, hydrogen, and oxygen, let's take a look the molecule that these atoms form.
The above illustration shows the structure of a carbohydrate molecule (this particular one is called glucose). We can see that carbons are bonded together in a ring, with bonding to other atoms on the side. We call these side groups, functional groups. This typical carbohydrate structure is shared by all types of carbohydrates. This simply means that different carbohydrates may have additional atoms bonded to this structure, but this structural "backbone" will always be present. And no matter what the type of carbohydrate we are considering, it follows this formula, which can be easily represented by this formula.
From this illustration we can see that there are 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms. If we compare the numbers of hydrogen atoms to the number of oxygen atoms, we see that there are 12 hydrogen atoms compared to only 6 oxygen atoms. Thus, there are twice as many hydrogen atoms as there are oxygen atoms. So, what's so important about this? Well, if we look at water (H2O), we can see that there are also twice as much hydrogen as there is oxygen. Therefore, carbohydrates follow this pattern of ratios, and historically, this is how the name originated (hydrate-from the Greek, hydro, water, and carbo=carbon, thus, hydrate of carbon). This compound was so named because it was associated with water.
Note on atomic symbols: These letter abbreviations for the atom are merely historical latin names for each element. This system was invented by Swedish chemist J闇祍 Berzelius. Although they are of historical interest, these names provide us with an easy to use, shorthand to work with. Don't worry, you don't have to know all 92. We shall teach you the abbreviation of each element as we go along.