Lipids, carbohydrates and nucleic acids may all vary in their structure, but they are all important to the human body, for they serve a variety of vital functions. Without them, the cells would not have energy or normal membranes, hormones and vitamins would be abnormal, and the body would not have enough antioxidants or even DNA.
There are different types of lipids, but what they all have in common is that they do not dissolve in water. Fatty acids are lipids made of long chains of hydrogen and carbon. Waxes are made of fatty acids and alcohols. Sphingolipids may have fatty acids, alcohol, phosphate and nitrogen, while triacylglycerides are made of a substance called glycerol and three fatty acids. Fats are triacylglycerides that are solid at room temperature, but when the triacylglycerides are liquid, they are called oils. Phospholipids are lipids composed of fatty acids and phosphate, while isoprenoids have a five-carbon structure.
Carbohydrates are molecules that are made out of the same amount of water and carbon. The simple sugars are called monosaccharides. They include ribose, fructose and glucose. If two monosaccharides join with one another, they form disaccharides, like lactose and sucrose. When many monosaccharides join together, they form what is called the polysaccharides, and this group includes starch and glycogen. Glycogen is the storage form of glucose, stored mainly in the muscles and liver.
There are two kinds of nucleic acids. There is deoxyribonucleic acid, or DNA, and ribonucleic acid, or RNA. All nucleic acids are made of structures called the nucleotides. Every nucleotide is made of phosphate, a ribose or deoxyribose sugar, and a structure called a base which contains nitrogen. Adenine, thymine, cytosine, guanine and uracil are the names of the bases. Adenine, thymine, cytosine and guanine are bases in DNA, while adenosine, uracil, cytosine and guanine are the bases of RNA.
Functions of Lipids, Carbohydrates and Nucleic Acids
Sphingolipids and phospholipids are an important part of the membranes of cells, while fats and oils store energy. Lipids also form part of the nerve cells, hormones, pigments and vitamins. They send chemical signals, give protection and serve as antioxidants. Carbohydrates form part of the structure of cells and provide a quick energy for the cells. DNA makes up the genes, RNA makes proteins, and the nucleotides help to create energy.
- “Biochemistry”; Trudy McKee, James McKee; 1996
- “Ganong’s Review of Medical Physiology”; Kim Barrett, Ph.D., Susan Barman, Ph.D., et al.; 2010
- Centers of Disease Control: Carbohydrates