Phosphorus on both orthophosphate and pyrophosphate is surrounded by 10 electrons. This does not satisfy the octet rule in either case, so that answer choice is false, and therefore the correct answer. With four negative charges close by, pyrophosphate is very unstable, and releases a lot of energy when cleaved. Finally, the two orthophosphates formed from a single pyrophosphate gain an additional resonance structure.

The type of bond that holds the phosphate group to the sugar in DNA's backbone is called a phosphodiester bond. Hydrogen bonds connect bases to one another and glycosidic bonds occur between deoxyribose groups and the base groups.

The type of loop of tRNA at the anticodon sequence is indeed hairpin. Hypoxanthine is occasionally found in tRNA anticodons (as its nucleoside, inosine). tRNA anticodons and mRNA codons are indeed antiparallel (this is central to their functioning). However, just because an anticodon has guanine in position one, doesn’t mean in cannot code with any of the four codons to make the same amino acid; the amino acid produced will be subject to whatever combination of bases is present, as detailed in the genetic code.

The two pyrimidine bases are cytosine and thymine. Purine bases are larger in structure than pyrimidines and possess a two-ring nitrogenous base. In RNA, uracil is also a pyrimidine. One way to help us remember which nitrogenous bases are which is to use the mnemonic CUT. Pyramids (like pyrimidines) are "sharp" and thus they CUT, Cytosine, Uracil and Thymine.

DNA nucleotides have a maximum absorbance at 280 260nm. Pyrimidines Purines have a larger structure than purines pyrimidines, since purines have two rings in their structures, and the pyrimidines have only one. All DNA nucleotides have tautomeric forms, and the lactim or enol lactam or keto form is more common. The structure of adenine is identical to guanine with the exception of one additional amino group on carbon #2 and a double bonded oxygen replacing the amino group on carbon #6.

Thymine and uracil a both pyrimidines with similar structure but a key difference at the 5' carbon. While this location is methylated in thymine, there is no functional group there in uracil.

Adenine and guanine are purines (contain two rings). Thymine, cytosine, and uracil are pyrimidines (contain one ring). In normal base pairing, a purine matches to a pyrimidine. Adenine matches to thymine in DNA (uracil in RNA), and cytosine matches to guanine. Ribulose is a carbohydrate.

In DNA and RNA, there are two types of nitrogenous bases: pyrimidines and purines. A pyrimidine contains one carbon-nitrogen ring with two nitrogen atoms. A purine consists of a pyrimidine fused with an imidazole ring. Adenine and guanine are purines. Cytosine, thymine, and uracil are pyrimidines.

When purines are broken down, they go through the intermediates hypoxanthine and xanthine, then are converted to uric acid. Xanthine oxidase is the enzyme that converts xanthine to uric acid. Treatments for gout are suicide inhibitors of xanthine oxidase, lowering the production of uric acid and building up the intermediates. This is preferable, because unlike uric acid, the intermediates are highly soluble.

tRNA carries the anticodon. tRNA is a transfer ribonucleic acid; it is a type of RNA molecule that decodes the mRNA sequence to form a protein. The anticodon is the part of the tRNA structure that complements the mRNA codon, dictating the identity of the amino acid carried by the tRNA and required to build the proper polypeptide chain.