Nucleotide

Nucleotides are important tiny parts in living things. They are made of three smaller parts: a nitrogenous base, a five-carbon sugar, and a phosphate group. They help build DNA and RNA, which carry instructions for all living things on Earth. These molecules are in every cell and are very important for life.

There are different kinds of nucleotides, each with a special nucleobase. In DNA, the bases are guanine, adenine, cytosine, and thymine. In RNA, uracil replaces thymine. Nucleotides also give cells energy. For example, adenosine triphosphate, or ATP, is a nucleotide that helps cells do many jobs, like building proteins.

Nucleotides help in many body processes. They help cells talk to each other and help enzymes do important jobs. Some nucleotides are added to food to give it a nice, umami flavor.

Structure

A nucleotide has three parts: a five-carbon sugar, a special base called a nucleobase, and one or more phosphate groups. When these three parts join together, we call it a nucleoside with 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 instructions for all living things. They also help store energy, send signals inside cells, and help enzymes do 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 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. The liver helps make 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 from a special molecule and then linked to a sugar. Purines are made by adding pieces to a sugar. Both types help create DNA and RNA, the molecules that carry our genetic information.

Quantification of dNTP pools

Scientists measure special molecules called deoxynucleoside triphosphates (dNTPs) inside cells to learn how DNA works and stays stable. If these molecules are not balanced, it can cause problems in DNA.

They use tools like liquid chromatography and mass spectrometry to measure these molecules very accurately.

Measuring other types of these molecules 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 look at how life's important parts could form on early Earth. The RNA world idea says that RNA might have been one of the first molecules, made from smaller parts called ribonucleotides.

Ribonucleotides are made from purine and pyrimidine nucleotides. These help store and share information.

Scientists found ways these molecules could form from simple substances. For example, pyrimidine parts can form using small molecules and ribose, with help from wet and dry cycles. Similar steps can make purine parts. With minerals that have phosphate, these pieces can join to make longer chains called polyribonucleotides. These 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 building block for DNA made by scientists in a lab. It does not exist in nature. Examples include d5SICS and dNaM. These special nucleotides have unique structures that can pair together in DNA. Scientists have made bacteria called E. coli 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 be used to edit genes in special 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 tools that let scientists edit genes, which may lead to new medical treatments in the future.

Length unit

Nucleotide (abbreviated "nt") is a 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, the tiny building blocks that help make up DNA and RNA. Scientists sometimes use extra codes when they make 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. Inosine is useful, but it is not in the main table of codes because it is a real nucleotide.