![]() The table below summarizes the possibilities. The other oxygens in the backbone can only act as hydrogen bond acceptors. The oxygens at atom 7 can act as either a donor or an acceptor. Unlike the backbone of a protein, DNA backbone doesn't contain any nitrogen atoms, so hydrogen bonding must involve oxygen atoms. In RNA, atom 12 is the oxygen in the hydroxyl group, and the first base atom is 13. The first atom of the base in DNA is atom 12. Atom numbering continues normally from there, and no "virtual atoms" are involved. Since there's no next DNA segment, the oxygen at atom 9 is not attached to a phosphate group. Foldit still identifies atoms 1 through 4 as being present, and these "virtual atoms" can even be banded.įor the last DNA segment in a chain, numbering is more straightforward. The first atom visible is atom 5, a carbon attached to the deoxyribose ring. ![]() Atom 10 is a carbon (carbon 1'), which is where the actual DNA base is attached.įor the first DNA segment in a chain, the phosphate group is missing. Atom 9 is an oxygen which joins the phosphate group of the next DNA segment. Foldit considers one of the oxygen atoms of the phosphate to belong to the deoxyribose of the preceding segment, so only the oxygen atoms 2 through 4 are numbered.Ītom numbering continues with the dexoyribose group. Foldit starts numbering with the phosphorous in the phosphate group. For example, the C terminal of a chain has an extra backbone atom, so it's beta carbon, the first atom of the sidechain, is 6 instead of 5.įor DNA, the backbone atoms always have the same number, regardless position in the chain. In a protein, the number of atoms in a segment is different depending on its position in the chain. The rules for numbering atoms are different in DNA, however. Just as in a protein, Foldit can identify atom numbers in DNA. ![]() The statements below are based on the similarities between RNA and DNA. DNA has only been found in intro puzzles to date, which don't allow the use of the recipes used to verify RNA atom numbering. The hydroxyl group is what distinguishes RNA from DNA.Ĭaution: atom numbering for DNA has not been validated. In RNA, a hydroxyl group (oxygen and hydrogen) is attached to carbon 2'. The DNA base is attached to carbon 1' of the deoxyribose. The carbon atoms are referred to as 1', 2', 3' and 4'. The sugar group in the DNA backbone is always a form of deoxyribose, a pentagonal ring consisting of an oxygen atom and four carbon atoms. Each segment of DNA or RNA is linked to the next by a phosphate. A phosphate group consists of a phosphorous atom bound to four oxygen atoms. It consists of 5-carbon deoxyribose sugars and phosphate groups. This is why "RNA" stands for "ribonucleic acid", and "DNA" stands for "deoxyribonucleic acid".īoth DNA and RNA backbone consists of alternating groups phosphates and sugars. DNA is made up of the sugar-phosphate backbone. Deoxyribonucleic acid is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The difference is that RNA backbone contains the sugar ribose, while DNA backbone contains the sugar deoxyribose. The blue numbers 1' to 4' refer to the carbons in the in deoxyribose ring.ĭNA backbone is more complicated than the backbone of the amino acids in a protein.ĭNA backbone is highly similar to RNA backbone. ![]() When phosphate groups link together to form chains, as in ATP (adenosine triphosphate), the link looks like O-P-O-P-O-P-O, with two additional oxygen atoms attached to each phosphorus, one on either side of the atom.DNA backbone showing chemical groups. ![]() One atom of oxygen is connected to the 5-carbon in the sugar and to the phosphorus atom. The only difference between them is that 2'-deoxyribose has one less oxygen atom attached to the second carbon.Ī single phosphate group is PO 4 3. The carbons are numbered sequentially, to help keep track of where groups are attached. Both ribose and deoxyribose are 5-carbon sugars. In RNA, the bases are adenine, guanine, uracil, and cytosine. The sugarphosphate groups line up in a backbone for each single strand of DNA, and the nucleotide bases stick out from this backbone. In DNA, the bases are adenine (A), thymine (T), guanine (G), and cytosine (C). Cytosine, thymine, and uracil are pyrimidines. Purines and pyrimidines are the two categories of nitrogenous bases. ![]()
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