adenine
Meaning of adenine: A single small molecule doing two unrelated jobs: storing information in DNA and shuttling energy as part of ATP.
Definition of adenine
Adenine is one of the four bases that spell out the genetic code in DNA, where it always pairs with thymine. In RNA it pairs with uracil instead. Beyond heredity it forms the core of ATP, the molecule cells use to carry usable energy, and of several helper molecules that ferry electrons during the breakdown of food.
How does base pairing work?
DNA is a twisted ladder whose rungs are pairs of bases held together by weak bonds. Adenine has a shape and a bonding pattern that fit thymine and nothing else, so the two always face each other across the ladder. Guanine pairs with cytosine the same way. This strict pairing is what lets a cell copy DNA: split the ladder down the middle and each half dictates exactly how the missing half must be rebuilt. It is also how a gene is read into RNA, where uracil stands in for thymine.
What kind of molecule is it?
| Base | Family | Pairs with in DNA |
|---|---|---|
| Adenine | Purine, a double ring | Thymine |
| Guanine | Purine, a double ring | Cytosine |
| Cytosine | Pyrimidine, a single ring | Guanine |
| Thymine | Pyrimidine, a single ring | Adenine |
A double ring always faces a single ring, which keeps the ladder an even width along its length. Adenine belongs to the purine family, and that has a direct clinical consequence: purines break down to uric acid, and uric acid crystals settling in a joint cause gout.
What does it do outside DNA?
Attach adenine to a sugar and three phosphate groups and the result is adenosine triphosphate, or ATP. The bonds between those phosphates hold energy the cell releases by snapping one off, and nearly every energy requiring process in the body draws on it. The same chemical compound forms the backbone of the carriers that ferry electrons through the reactions extracting energy from food, and of cyclic AMP, which relays hormone messages inside cells. Adenine joined to sugar alone is adenosine, which slows conduction through the heart and is used for that effect.
Where does the body get it?
Cells build adenine from smaller pieces and also recycle it from broken down nucleic acids, a route that costs far less energy than starting over. Food contributes some, since all living tissue contains DNA. When many cells break down at once, the sudden purine load raises uric acid in the blood, which is why treatments that destroy large numbers of cells quickly are watched for that effect.
Used in a sentence
Sequencing showed a single adenine substituted for guanine at that position.
Good to know
Adenine is a purine, and purines break down to uric acid, so the rapid destruction of many cells can raise uric acid enough to injure the kidneys.
Word origin
Where “adenine” comes from
From the Greek aden, meaning gland, because the compound was first isolated from pancreatic tissue.