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![]() DNA's structure allows a molecule to copy itself and allows genetic messages to arrive without getting garbled on the journey. DNA is a huge molecule called a macromolecule. However, DNA fits into small cells because it is packed in a process called supercoiling, in which DNA is wrapped around proteins called nucleosomes. Proteins called histones hold the coils together. Strands of DNA are divided into chromosomes, a full set of which is stored in the nucleus of each cell. These chromosomes, which basically instruct how the entire body is built, are called genes. A gene determines how a specific trait will be expressed. Chemically, DNA is made of three components: nitrogen-rich bases, deoxyribose sugars, and phosphates. When combined, these components form a nucleotide. Nucleotides come together in pairs to form a single molecule of DNA. There are four nitrogen-rich bases. These are adenine, guanine, thymine, and cytosine. Adenine and guanine have purine bases, which means they are a compound of two rings. Thymine and cytosine have pyrimidine bases, which means they have a single six-sided ring structure. These rings stack up in DNA to make the molecule compact and strong. In order to make a complete nucleotide, the bases are attached to deoxyribose and a phosphate molecule. Nucleotides are the building blocks of DNA. To make a complete DNA molecule, these nucleotides join together to make matched pairs and form long double strands called double helixes. DNA-Structure.com features information about the structure of DNA and the history of DNA testing, as well as DNA testing services and solutions. Bibliography
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