Carbohydrates, Lipids, and Nucleic Acids



Carbohydrates, lipids, and nucleic acids are molecules important to life. Carbohydrates mainly serve to provide cells with energy, mostly as sugars. In plants, energy is often stored as starch; in animals, some is stored as glycogen. In plants, carbohydrates—in the form of cellulose—provide structural support, while chitin can act as structural support in fungi and some animals. Carbohydrates in the cell membrane allow for cell recognition, including the blood type markers of red blood cells. Lipids provide long-term energy storage, packing more energy per gram than carbohydrates. Saturated fatty acids contain the most energy, having the maximum number of hydrogens. Unsaturated fats have one or more double bonds and thus fewer hydrogens. Lipids, in the form of steroids, can also regulate growth and maintenance. For example, cholesterol builds some vitamins and provides support for the cell membrane. Nucleic acids make up the genetic material of cells. Deoxyribonucleic acid (DNA) stores the cell's genetic information, while ribonucleic acid (RNA) assists in protein synthesis. Adenosine triphosphate (ATP) serves as the unit of chemical energy for the cell.

At A Glance

  • Carbohydrates are the main source of energy for the cell, provide some structural support for cells, and function in cell recognition.
  • Lipids provide long-term energy storage, support the cell membrane, and help regulate the growth and maintenance of the organism.
  • The nucleic acid deoxyribonucleic acid (DNA) forms the genetic material of cells and the nucleic acid ribonucleic acid (RNA) has roles in coding, regulation, and expression of genes; the nucleotide adenosine triphosphate (ATP) is the chemical unit of energy for cells.