Nucleotide

Nucleotides are important organic molecules made up of three parts: a nitrogenous base, a five-carbon sugar, and a phosphate group. They are the building blocks of DNA and RNA, two types of nucleic acids that carry the genetic instructions for all living things on Earth. These molecules are found in every cell and are essential for life.

There are different types of nucleotides, each with a specific nucleobase. In DNA, the bases are guanine, adenine, cytosine, and thymine. In RNA, uracil takes the place of thymine. Besides their role in storing and sharing genetic information, nucleotides also provide energy for cells. For example, adenosine triphosphate, or ATP, is a nucleotide that supplies energy for many cell activities, such as making proteins and moving parts of the cell.

Nucleotides are involved in many other important processes in the body. They help cells communicate through signaling and act as helpers for enzymes that carry out various chemical reactions. Some nucleotides are even used in food to enhance flavor, giving foods a savory, umami taste.

Structure

A nucleotide is made up of three parts: a five-carbon sugar, a special base called a nucleobase, and one or more phosphate groups. When all three parts are joined together, we call it a nucleoside mono-, di-, or triphosphate, depending on how many phosphate groups it has.

Nucleotides are the building blocks of DNA and RNA, the molecules that carry the instructions for all living things. They can also help store energy, send signals inside cells, and assist enzymes in their work. Some important examples include cAMP, pppGpp, NADP, and FAD.

Synthesis

Nucleotides can be made in different ways, both inside and outside living cells. In laboratories, scientists protect certain parts of nucleotides to create new ones that do not exist in nature.

Inside our bodies, nucleotides are made in two main ways. One way builds them from scratch using pieces from our food, like sugars and certain building blocks. The liver is especially important for making nucleotides this way. The other way recycles old nucleotides into new ones.

There are two main types of nucleotides: pyrimidines and purines. Pyrimidines are made first from a special molecule and then linked to a sugar. Purines are made by adding pieces one by one to a sugar, forming a ring structure. Both types are important for creating DNA and RNA, the molecules that carry our genetic information.

Quantification of dNTP pools

Scientists need to measure special molecules called deoxynucleoside triphosphates (dNTPs) inside cells to understand how DNA works and stays stable. If these molecules are out of balance, it can cause problems like more mistakes in DNA. They use tools like liquid chromatography and mass spectrometry to measure these molecules very accurately.

There are also other types of these molecules that are not the usual ones, and measuring them helps scientists learn about diseases like cancer. New methods make it easier to study these molecules, even in small samples.

Prebiotic synthesis of nucleotides

Theories about the origin of life explore how life's key building blocks could form under early Earth conditions. The RNA world hypothesis suggests that RNA was one of the first molecules to exist, made from smaller molecules called ribonucleotides. These ribonucleotides are made of purine and pyrimidine nucleotides, which are important for storing and sharing information.

Scientists have discovered ways that these important molecules could form from simple substances. For example, pyrimidine parts can be created using small molecules and ribose, helped by wet-dry cycles. Similar steps can make purine parts. With minerals that contain phosphate, these pieces can come together to form longer chains called polyribonucleotides, which are the building blocks of RNA.

Unnatural base pair (UBP)

Main article: Base pair § Unnatural base pair (UBP)

An unnatural base pair (UBP) is a special kind of building block for DNA that scientists create in a lab. It doesn’t exist in nature. Examples include d5SICS and dNaM. These special nucleotides have unique structures with two fused rings that can pair together in DNA. Scientists have even made bacteria called E. coli able to pass these artificial nucleotides through many generations, showing that living things can carry an expanded genetic code.

Medical applications of synthetic nucleotides

Synthetic nucleotides have many important uses in medicine. They help doctors treat diseases and can even be used to edit genes in precise ways. For example, some special nucleotides are used to fight viruses like Hepatitis and HIV.

Doctors also use synthetic nucleotides to turn off harmful genes in rare diseases. This helps treat conditions that used to have no cure. These nucleotides can also guide powerful tools that let scientists edit genes, opening new doors for future medical treatments.

Length unit

Nucleotide (abbreviated "nt") is a common unit used to measure the length of single-stranded nucleic acids, just like base pair is used for double-stranded nucleic acids. It helps scientists talk about the size of these important molecules in a simple way.

Abbreviation codes for degenerate bases

Main article: Nucleic acid notation

The IUPAC has special symbols for nucleotides, which are tiny building blocks that help make up DNA and RNA. Sometimes, scientists use extra codes when they are making special tools called PCR primers. These codes help the primers match the right parts of DNA. One of these extra codes is "I", which stands for a nucleotide called inosine. Inosine is found in molecules called tRNAs and can pair with three different nucleotides: adenine, cytosine, or thymine. Even though inosine is useful, it is not listed in the main table of codes because it is a real nucleotide, not just a mix of possibilities.