Nucleic acids are a class of biomolecules that are found in all living organisms and are responsible for the storage of genetic information. They are also responsible for protein synthesis. Nucleic acids are made up of monomers called nucleotides.
Nucleotides are made up of three components, a 5-carbon sugar such as ribose, a phosphate functional group, and a nitrogenous base. The 5-carbon sugar present in DNA is deoxyribose, and the four nitrogenous bases are adenine, guanine, cytosine, and thymine. Nucleotides are linked together by dehydration synthesis, or polymerization reactions, between the sugar of one nucleotide and the phosphate group of a second nucleotide. In the process, a sugar-phosphate backbone is formed, linking the nucleotides together. Notice how the nitrogenous bases project to one side of the backbone.
DNA is composed of two strands arranged as a right-handed helix. The strands are also anti-parallel, meaning that they are oriented in opposite directions. The two strands are held together by hydrogen bonds. Guanine forms hydrogen bonds with cytosine, and adenine bonds with thymine. This complementary base pairing links the strands together.
It also plays an important role in the replication of the DNA molecule. RNA differs from DNA in that it contains the sugar ribose instead of deoxyribose and the nitrogenous base uracil instead of thymine. Also, RNA is usually single-stranded and does not typically form a helix.
Because of this, it is less stable than DNA and is usually more temporary. While DNA stores the information that is needed to construct a protein, RNA functions in regulating the expression of this information in the protein synthesis process. Not all nucleic acids are involved in information processing in the cell.
ATP, or adenosine triphosphate, is a modified nucleotide that plays a central role in energy processing within cells. ATP is composed of the nitrogenous base adenine bound to the sugar ribose, just like in RNA. However, three phosphate groups can be added to the molecule. The bonds between the phosphate groups are high-energy bonds. These molecules are called adenine bonds.
These molecules serve as temporary energy batteries for the cell. When energy is needed, the terminal phosphate group is removed, releasing energy and forming adenosine diphosphate, which may then be recharged by the energy pathways of the cell.