“The book of life”, that’s what DNA is called, but what does that really mean? How is DNA like a book? And just what is written in that book?
DNA is like the instruction manual for all living things. If it’s alive, it has DNA. It’s the instruction manual because it provides the information on how to build an organism, everything from the tinniest bacteria to the humble potato, not to mention people. To understand how that works, we have to go right to the basics of what DNA is – but don’t worry, it’s not even that complicated.
A book is a coherent message made up of a long chain of letters, the alphabet. For DNA, the message is how to build a living organism and the alphabet is made up of nucleotides instead of letters. Instead of 26 letters, there are only 4 nucleotides. So to understand DNA we need to understand what the 4 nucleotides are.
A nucleotide is a small molecule with three parts. The first two parts make up the “backbone” and are the same in all nucleotides. The backbone of different nucleotides can link together, like a chain, and also connect to the third part, which is called a base. It’s a base in the chemistry sense, but those details aren’t important right now. The thing to know is that nucleotides can form long chains, millions of nucleotides long, with loose bases sticking out.
The four bases of the nucleotides are called adenine, guanine, cytosine, and thymine, or A, G, C and T for short. There you have it, a long chain of nucleotides.
DNA stands for Deoxyribonucleic acid. It sounds a lot tougher than it is. Deoxyribose refers to the backbone part, and nucleic acid means its an acid found in the nucleus, the special area of the cell where DNA is stored. It’s called an acid in the chemistry sense of the word.
