Key Difference – Nucleotide vs Nucleic Acid
Nucleic acids are macromolecules found in organisms. There are two main types of nucleic acids named DNA and RNA. DNA serves as the repository of genetic or heredity information in almost all organisms. In some organisms, RNA serves as the genetic component of the organism. Nucleic acids are composed of thousands of basic units called nucleotides. RNA is made up of ribonucleotides and DNA is made up of deoxyribonucleotides. The key difference between nucleotide and nucleic acid is that nucleotide is a building block of nucleic acid while a nucleic acid is a polymer of nucleotides.
CONTENTS
1. Overview and Key Difference
2. What is Nucleotide
3. What is Nucleic Acid
4. Side by Side Comparison – Nucleotide vs Nucleic Acid
5. Summary
What is a Nucleotide?
Nucleotide is a basic unit of nucleic acids. They are the building blocks or monomers of DNA and RNA. They link with each other to form a polynucleotide chain which gives the structure to DNA or RNA. A nucleotide is composed of three main components. They are a nitrogenous base, a pentose sugar (five carbon sugar), and phosphate groups. There are five different nitrogenous bases namely Adenine, Guanine, Thymine, Uracil, Cytosine. Thymine is seen only in DNA while uracil is unique to RNA. There are two types of five carbon sugars in nucleic acids. RNA contains ribose sugar while DNA contains deoxyribose sugar. Nucleotide contains three phosphate groups attached to a pentose sugar.
Nucleotides form phosphodiester bonds between 3’OH and 5’ Phosphate groups of adjacent two nucleotides to create the polynucleotide chain. Nitrogenous bases form hydrogen bonds between complementary bases in the double stranded DNA. Nucleotides are named with the three main letters such as ATP, GTP, CTP, TTP, UTP, etc. The first letter refers to the nitrogenous base. Second and third letters refer to the number of phosphate groups and phosphate. Nucleotide can bear a maximum of three phosphate groups, and it is also possible to have one phosphate group in a nucleotide. A nucleotide without a phosphate group is known as a nucleoside.
Nucleotides in cells have different functions. They facilitate the storage of genetic information within its sequence. Some nucleotides behave as the energy currency in the cells (as an example – ATP). Several nucleotides act as secondary messengers and take part in cell communication (cAMP, cGTP). Some nucleotides also catalyze enzymatic reactions by acting as coenzymes.
Figure 01: Nucleotide
What is a Nucleic Acid?
Nucleic acids are biopolymers composed of millions of monomers called nucleotides. There are two main types of nucleic acids: DNA and RNA. DNA and RNA differ in their compositions. The main difference between DNA and RNA is that DNA contains deoxyribose sugar while RNA contains ribose sugar as indicated by their names. In addition, adenine forms hydrogen bonds with thymine in DNA while adenine forms hydrogen bonds with uracil instead of thymine in RNA.
Nucleic acids, mainly DNA, contain genetic information of the organisms. Therefore, they are considered to be the most important biomolecules in the cells which allow the genetic information to reach the next generations. RNA is the second type of nucleic acid which contains the genetic codes which are encoded for proteins. Hence RNA is essential for protein synthesis in cells. There are several types of RNA. Messenger RNA (mRNA) is the RNA produced by DNA transcription in which the information is hidden to make proteins. Ribosomal RNA (rRNA) is located in the ribosome and is involved in protein synthesis from mRNA. Transfer RNA (tRNA) is a type of RNA involved in the translation of mRNA into amino acid sequence. MicroRNA (miRNA) is small RNA molecule involved in regulation of gene expression.
DNA most commonly exists as a double stranded molecule in organisms while RNA is more common in single stranded form.
Figure 02: Nucleic Acids
What is the difference between Nucleotide and Nucleic Acid?
Nucleotide vs Nucleic Acid |
|
| Nucleotide is a basic unit of nucleic acids. | Nucleic acids are biopolymers composed of millions of monomers called nucleotides |
| Structure | |
| Nucleotide is a monomer. | Nucleic acid is a polymer. |
| Composition | |
| Nucleotide is composed of pentose sugar, nitrogenous base & phosphate group. | Nucleic acids are composed of polynucleotide chains. |
| Classification | |
| There are several nucleotides such as ATP, GTP. CTP, TTP, UTP etc. | There are two main types called DNA and RNA. |
Summary – Nucleotide vs Nucleic Acid
Nucleotide is a building block or the basic structural unit of nucleic acids. They are composed of phosphate groups, nitrogenous bases and pentose sugars. Nucleotides link together by phosphodiester bonds to form polynucleotide chains. Nucleic acid is a polymer made up of polynucleotide chains. There are two main types of nucleic acids named DNA and RNA. DNA is essential for storing and transferring genetic information while RNA is essential for protein synthesis and other several functions in the cells.
References
1. “Nucleic acids (article).” Khan Academy. N.p., n.d. Web. 20 Apr. 2017
2. “Nucleic acid.” Wikipedia. Wikimedia Foundation, 16 Apr. 2017. Web. 20 Apr. 2017
Image Courtesy:
1. “0322 DNA Nucleotides” By OpenStax – (CC BY 4.0) via Commons Wikimedia
2. “Difference DNA RNA-EN” By Difference_DNA_RNA-DE.svg: Sponk (talk)translation: Sponk (talk) – chemical structures of nucleobases by Roland1952 (CC BY-SA 3.0) via Commons Wikimedia