From the sandy creek in the Cajon Pass, into Lone Pine Canyon, up and along the Blue Ridge to the summit of Mt. Baden-Powell, then edging along to Islip Saddle, the trail within proximatey to Wrightwood provides views of the extended metropolitan areas of Southern California and the Mojave Desert.
Guanine, along with adenine and cytosine, is present in both DNA and RNA, whereas thymine is usually seen only in DNA, and uracil only in RNA. Guanine has two tautomeric forms, the major keto form (see figures) and rare enol form. It binds to cytosine through three hydrogen bonds.
Cytosine is also a pyrimidine base. It binds to guanine in the DNA structure. Cytosine consists of oxygen, hydrogen, carbon and nitrogen. Like all pyrimidine bases, cytosine has a one-ring structure with six members. Cytosine, like thymine, can be converted to uracil in RNA, and cytosine is the most unstable of the four nucleotides. Because it is unstable, the bond between cytosine and guanine is the bond most easily broken within the DNA strand.