Deoxyribonucleic acid, or DNA, is a polymer of nucleotides linked together by specific bonds known as phosphodiester bridges. The phosphate group (PO3) of one nucleotide links to the hydroxyl group (OH) of the following nucleotide.Hundreds of millions of these linkages occur within the DNA polymer.he two DNA strands are held together by interchain hydrogen bonds. H-bonds pair the bases in one chain to the complementary bases in the other chain. (A/T and G/C).
The master circadian pacemaker in mammals is located in the suprachiasmatic nucleus in the rostroventral hypotha-lamus (Figure 2). Lesion studies identified it in 1972, and in vitro and in vivo functional studies, as well as transplant studies, have repeatedly corroborated the finding since then.
What Is the Circadian Rhythm? Often referred to as the body clock, the circadian rhythm is a cycle that tells our bodies when to sleep, rise, eat--regulating many physiological processes. This internal body clock is affected by environmental cues, like sunlight and temperature.