Nitrogenous Base

Nitrogenous Base Definition

Nitrogenous bases, chemicals with similar cyclic structures, play an important role in biology. In addition to building genetic information carrying molecules like DNA and RNA, nitrogenous bases serve various cellular functions, such as signal transduction and microtubule growth.

Nitrogenous bases form bonds with 5-sided carbon sugar molecules in DNA and RNA, which form the molecule’s “backbone”. DNA and RNA are built from nitrogenous bases and sugar backbones, referred to as nucleotides.

Nitrogenous Base within Nucleic Acids

Purines and Pyrimidines

In DNA or RNA, nitrogenous bases can be divided into two types based on their base class. There is one characteristic that all nitrogenous bases share: a six-sided ring with 4 carbon atoms and 2 nitrogen atoms. One carbon atom and two nitrogen atoms are added to purines to create a 5-sided ring. Only one six-sided ring is present in pyrimidine nitrogenous bases. Since nitrogenous bases have unique bonds, they function differently within DNA and RNA.

Deoxyribonucleic Acid (DNA)

Deoxyribose is the “backbone” of DNA, shown here as colorless molecules with a 5′ and 3′ end. DNA’s directionality and readability are determined by the exposed carbons in the sugar chain. Various proteins can read and process DNA efficiently as a result.

The colored molecules represent nitrogenous bases. Each nitrogenous base pairs with the nitrogenous base across from it. In DNA replication, repair, and maintenance, this is called base pairing. Several hydrogen bonds are formed when each pyrimidine pairs with a purine in a proper configuration. Dashed lines represent these bonds, which hold DNA in a spiraling shape and prevent nitrogenous bases from breaking off accidentally.

An enzyme that repairs and maintains DNA may be able to detect malformations caused by a lack of hydrogen bonding. Two purines, for example, could not form hydrogen bonds if they tried to pair. It would be detected by a repair enzyme when there is a bulge or irregularity in the DNA. The incorrect base can then be removed and replaced by certain enzymes.

Ribonucleic Acid (RNA)

DNA and RNA differ in two important ways. First, there is the name itself. Deoxyribose is the building block of DNA, whereas ribose is the building block of RNA. Oxygen is the only difference between ribose and deoxyribose.

RNA uses a slightly different set of nitrogenous bases than DNA. An RNA molecule substitutes uracil for thymine. The reasons for this are not fully understood, although RNA is generally a shorter lived molecule. 

Further, RNA often exists as a single-strand, rather than a double-strand with hydrogen bonds. This is not always the case, as seen in double-stranded RNA viruses, but RNA is typically single stranded in most animals.

Regardless of whether the nucleic acid is DNA or RNA, the basic formula is the same. Take a nitrogenous base, add on a 5-carbon sugar with a phosphorous group, and bind together. The bonds formed between the phosphorous group and the oxygen of the next 5-carbon ring are called a phosphodiester bond, and form the backbone of both RNA and DNA.

How a Nitrogenous Base Carries Genetic Information

Each nitrogenous base carries little information itself. Rather, each nitrogenous base is read as a unit, with two other bases. These three-base information packets are called codons. Each codon specifies a certain amino acid. Put together in proper order and folded into shape, a chain of amino acids creates a protein. These proteins then carry out the functions of life, including everything from growth to reproduction.

It takes around 3,000,000,000 base pairs to create a functioning human. This means that there are around 6,000,000,000 individual bases in each cell of your body. While this may seem like an enormous amount, your body is constantly processing and replicating your DNA. This is probably the main and most important function of a nitrogenous base for any organism.

Nitrogenous Bases in Other Cell Functions

Energy Transfer

Genetic information storing is not the only task of a nitrogenous base. Many are used in the transfer of energy between food molecules like glucose and the energy needs of proteins within the cell. The most recognized of these molecules is adenine triphosphate, more commonly known as ATP. While biology textbooks often refer to this molecule as the cell’s universal energy transfer molecule, it is important to note that it is based on adenine, the nitrogenous base.

While ATP is widely recognized in a number of cellular reactions, it is not the only nitrogenous base that serves in cellular energy transfer. Another molecule, guanine triphosphate (GTP), is used in a number of cellular functions. GTP opens protein channels, aids in the formation of microtubules, and even energizes the import of important proteins into the mitochondria. This in turn helps produce more ATP via aerobic respiration, which powers the cell’s growth.

Cell Signaling

A nitrogenous base can also serve important roles in cell signaling, a process known as signal transduction. The general scheme involves a number of chemical messengers acting on various proteins within a cell to send a signal. A pancreas cell may measure the blood glucose, transduce a signal to release insulin, and disperse the insulin into the blood stream. This process is integrated and coordinated by a number of factors involving a nitrogenous base.

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