The key difference between amino acid and nucleotide is that the amino acid is the building block of proteins while the nucleotide is the building block of nucleic acids.
Macromolecule is a large molecule resulting due to polymerization of its monomers. The most common macromolecules found in living organisms including plants are nucleic acids (DNA and RNA), proteins, lipids, carbohydrates, etc. Among the different macromolecules, proteins and nucleic acids are vital for the survival of the organisms. Amino acids and nucleotides are the building blocks of proteins and nucleic acids respectively. Both are organic molecules and present in high concentrations inside cells.
CONTENTS
1. Overview and Key Difference
2. What is Amino Acid
3. What is Nucleotide
4. Similarities Between Amino Acid and Nucleotide
5. Side by Side Comparison – Amino Acid vs Nucleotide in Tabular Form
6. Summary
What is Amino Acid?
The amino acid is the simplest unit of proteins. There are about twenty different amino acids. All amino acids have a -COOH and -NH2 groups and a -H bonded to a carbon. The carbon is a chiral carbon, and alpha-amino acids are the most important in the biological world. D-amino acids are not present in proteins and not a part of the metabolism of higher organisms as well. However, several are important in the structure and metabolism of lower forms of life. The R group differs from one amino acid to another. The simplest amino acid with the R group being H is glycine. According to the R group, amino acids can be categorized into aliphatic, aromatic,non-polar, polar, positively charged, negatively charged, or polar uncharged, etc.
Figure 01: Amino Acid
Amino acids are the building blocks of proteins. When two amino acids join to form a dipeptide, the linkage which is a peptide bond occurs between NH2 group of one amino acid with the COOH group of the other amino acid by forming a water molecule. Thousands of amino acids can be condensed like these to form long peptides, which are then folded to make proteins.
What is Nucleotide?
Nucleotide is the building block of two crucial macromolecules DNA and RNA. They are the genetic material of an organism and are responsible for passing genetic characteristics from generation to generation. Furthermore, they are important to control and maintain cellular functions. Other than these two macromolecules, there are other important nucleotides. For example, ATP (Adenosinetriphosphate) and GTP are important for energy storage. NADP and FAD are nucleotides, which act as cofactors. Nucleotides like CAM (cyclic adenosine monophosphate) are essential for cell signalling pathways.
A nucleotide has three components namely a pentose sugar molecule, a nitrogenous base and the phosphate group/s. According to the type of pentose sugar molecule, a nitrogenous base and the number of phosphate groups, nucleotides differ from each other. For example, in DNA, there is a deoxyribose sugar in the deoxyribonucleotide while in RNA, there is a ribose sugar in the ribonucleotide.
Moreover, there are mainly two groups of nitrogenous bases as pyridines and pyrimidines. Pyrimidines are smaller heterocyclic, aromatic, and six-membered rings containing nitrogens at 1 and 3 positions. Cytosine, thymine, and uracil are examples for pyrimidine bases. Purine bases are much larger than pyrimidines. Other than the heterocyclic aromatic ring, they have an imidazole ring fused to that. Adenine and guanine are the two purine bases.
Figure 02: Ribonucleotide
In DNA and RNA, complementary bases form hydrogen bonds between them. Adenine forms two H bonds with thiamine or uracil while guanine forms three H bonds with cytosine. The phosphates are linked to the –OH group of carbon 5 of the sugar. In the nucleotides of DNA and RNA, normally there is a one phosphate group. However, in other nucleotides such as ATP, there are more than one phosphate groups present.
What are the Similarities Between Amino Acid and Nucleotide?
- Amino acid and nucleotide are monomers or simplest units of two macromolecules.
- They are able to link with another same kind of molecule in order to form a polymer.
- Moreover, they are very important molecules.
- Also, each monomer has several types, and there are 20 different amino acids while there are several different nucleotides.
- Furthermore, both contain C, H, O and N atoms.
What is the Difference Between Amino Acid and Nucleotide?
An amino acid is a monomer of a protein molecule while a nucleotide is a monomer of a nucleic acid. Therefore, this is the key difference between amino acid and nucleotide. Moreover, the amino acid has C, H, N, O and S atoms while nucleotide has C, H, N, O and P atoms. Thus, this is another difference between amino acid and nucleotide. Furthermore, an amino acid has COOH, NH2 and R groups while a nucleotide has pentose sugar, a nitrogenous base and phosphate groups.
Below is an infographic of the difference between amino acid and nucleotide.
Summary – Amino Acid vs Nucleotide
There are different macromolecules. Among them, proteins and nucleic acids are utmost important. Proteins are responsible for many of the cellular functions while nucleic acids make the genomes of organisms. Structurally, amino acids are the building blocks of proteins. On the other hand, nucleotides are the building blocks of nucleic acids; DNA and RNA. Therefore, this is the key difference between amino acid and nucleotide. Furthermore, an amino acid molecule has COOH, NH2 and R group while a nucleotide has pentose sugar, a nitrogenous base and a phosphate group. Thus, this is another significant difference between amino acid and nucleotide.
Reference:
1.“Nucleotide.” NeuroImage, Academic Press. Available here
2. Reddy, Michael K. “Amino Acid.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 30 Oct. 2018. Available here
Image Courtesy:
1.”Amino-acid-structure”By Johndoct – Own work, (CC BY-SA 4.0) via Commons Wikimedia
2.”Ribonucleotide General”By Binhtruong – Own work, (CC BY-SA 3.0) via Commons Wikimedia
