Nucleotide Structure. The basic building block of DNA is the nucleotide. The nucleotide in DNA consists of a sugar (deoxyribose), one of four bases (cytosine (C), thymine (T), adenine (A), guanine (G)), and a phosphate. Cytosine and thymine are pyrimidine bases, while adenine and guanine are purine bases.
Block mountains form along fault blocks. Tension in a fault block can cause horsts in the fault block to tip. The horst edges point upward, forming a range of exposed mountains.
