Nepedia
Back to Discover
Advanced Reader
🧬

Nucleic acid

life science Maturity 11-13 Next article →

Nucleic acids are massive, essential biomolecules found in all living cells and viruses. They act as the primary carriers of biological information. These molecules create, encode, and store the instructions necessary for every life-form on Earth. This includes complex organisms like humans, simple bacteria, and even viruses.

Difference DNA RNA-EN
Difference DNA RNA-EN

By carrying specific sequences, nucleic acids direct the chemical processes that sustain life. They are classified as polynucleotides, which are long chains made of repeating units.

Each individual unit in these chains is called a nucleotide. A nucleotide consists of three distinct chemical parts. First, it contains a five-carbon sugar, also known as a pentose sugar. Second, it has a phosphate group, which gives the molecule its acidic properties. Third, it includes a nitrogenous base, often simply called a base. These nucleotides connect through phosphodiester linkages. The sugars and phosphates form an alternating backbone. The bases attach to the sugars via an N-glycosidic linkage. This structure creates a sequence that functions as a biological code.

There are two primary classes of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). The difference between them begins with the sugar used in the nucleotide. DNA uses a sugar called deoxyribose. RNA uses a sugar called ribose. The two molecules also use different sets of nitrogenous bases. Both DNA and RNA share adenine, cytosine, and guanine. However, DNA contains a unique base called thymine. RNA uses a different base called uracil instead.

Difference DNA RNA-EN
Difference DNA RNA-EN

DNA and RNA perform very different roles within a cell. DNA serves as the master storage for genetic instructions. These instructions are organized into segments called genes. In eukaryotic organisms, such as plants and animals, most DNA stays inside the cell nucleus. It is often organized into long, linear structures called chromosomes. During cell division, the cell undergoes DNA replication to copy these chromosomes. This ensures every new cell has a complete set of instructions.

RNA is responsible for converting those genetic instructions into functional proteins. There are three main types of RNA involved in this process. Messenger RNA, or mRNA, carries the genetic code from the DNA to the ribosomes. Ribosomal RNA, or rRNA, reads the sequence and helps build the protein. Transfer RNA, or tRNA, acts as a carrier for amino acids. These amino acids are the building blocks used to assemble the final protein. Through this process, the code in the DNA is expressed as physical traits.

Friedrich Miescher
Friedrich Miescher

The history of nucleic acid research is a journey of many discoveries. In 1869, the Swiss scientist Friedrich Miescher discovered a substance he called "nuclein" at the University of Tübingen. In the early 1880s, Albrecht Kossel purified this substance and identified the nucleobases. Richard Altmann later coined the term "nucleic acid" in 1889. In 1938, Astbury and Bell produced the first X-ray diffraction pattern of DNA. Later, the Avery–MacLeod–McCarty experiment proved DNA carries genetic information. Finally, in 1953, Watson and Crick proposed the famous double-helix structure.

Nucleic acids vary greatly in size and shape. DNA molecules are likely the largest individual molecules known to science. For example, a single human chromosome 1 contains 247 million base pairs. While DNA is usually a double-stranded helix, RNA is typically single-stranded. However, some viruses have genomes made of double-stranded RNA. The physical shape of these molecules is vital to their function. Double-stranded DNA forms a uniform helix with a diameter of about 20 Å. In contrast, single-stranded RNA can fold into complex three-dimensional shapes. These molecules are the foundation for modern biotechnology, forensics, and pharmaceutical industries.

592 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (2)
File:Difference_DNA_RNA-EN.svg
Difference_DNA_RNA-EN.svg
File:Friedrich Miescher.jpg
Friedrich Miescher.jpg
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.