Guanine is found in DNA.
Nucleotides are complex molecules that are the building blocks of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Each nucleotide has three parts: a five-carbon sugar, a phosphate group, and an organic base. There are two variations of the sugar, depending on whether the nucleotide is in a DNA or RNA molecule. In addition, each nucleotide can be attached to one of five different organic bases: adenine, cytosine, guanine, thymine, or uracil. Cytosine, guanine, and adenine are found in RNA and DNA molecules, while thymine is only found in DNA and uracil is only found in RNA.
Three hydrogen bonds join guanine and cytosine in DNA.
The five bases have a complex ring structure made up of carbon and nitrogen atoms. Due to the nitrogen atoms found in the ring, the bases are also called nitrogenous bases. Each of the bases has a different chemical structure from the other four, allowing for specific base pairing between each of the bases.
The five bases can be divided into two groups based on the number of rings found in their chemical structure. Purine bases are made up of two ring atoms and pyrimidine bases have only one ring of atoms. Purine bases include adenine and guanine, while pyrimidine bases include cytosine, thymine, and uracil. When bases pair and bond, purine bases only bond to pyrimidine bases. More specifically, adenine only binds to thymine or uracil and cytosine only binds to guanine.
Guanine is one of the four bases that make up RNA.
This specific base pair is very important for the stability of a DNA molecule, which is made up of two strands of nucleotides that coil to form a double helix. The two strands are held together by hydrogen bonds between complementary bases on each strand. Adenine and thymine are linked by two hydrogen bonds, while guanine and cytosine are linked by three hydrogen bonds. Only these pairs can form the hydrogen bonds necessary for the DNA molecule to be stable.
Due to the bonding that occurs only between the purine bases and the pyrimidine bases, the distance between the two strands remains uniform, adding more stability to the DNA molecule. When a purine base bonds with a pyrimidine base, a double-ring molecule bonds with a single-ring molecule. If a purine base were to bond to a purine base, then two double-ring molecules would bond, or if a pyrimidine base bonded to a pyrimidine base, then two single-ring molecules would bond. If all of these binding scenarios were to take place, the DNA molecule would bend in and out and be non-uniform, affecting its overall structure and stability. Having a stable DNA molecule is essential for success, as it carries the genetic information of each organism.