Carbohydrates

important when it comes to proteins that are affiliated with the cell membrane. Figure 35 indicates the different types of proteins structures:

Figure 35.

CARBOHYDRATES

Carbohydrates are the most abundant molecules on the planet. They provide the world with carbon and water. Carbohydrates always contain carbon, hydrogen, and water. There are a few that are attached to nitrogen, sulfur, or phosphorus but this is uncommon. They are an energy source, are used in certain cell membrane receptors, and are a part of what makes a nucleic acid. Polymers of carbohydrates will make things like glycogen for energy storage, chitin for cell wall formation and cellulose, which is also a cell wall component.

Carbohydrates are also referred to as saccharides. Monosaccharides are simple sugars and are the monomers that make polysaccharide chains. Carbohydrates are also named with the suffix -ose. A triose has three carbon atoms; a tetrose has four carbon atoms; a pentose has five carbon atoms and a hexose has six carbon atoms. Hexoses such as glucose are extremely abundant in nature. Disaccharides are also common. These two-

monomer molecules include things like sucrose, which is table sugar, and lactose, which is milk sugar. Figure 36 shows the sucrose molecule:

Figure 36.

Monosaccharides that have at least four carbon atoms are generally more stable as cyclic molecules. There is a chemical reaction between two functional groups at each end of the molecule so that the molecule become cyclic. Glucose, galactose, and other hexoses prefer to be cyclic in general.