Answer:
in the wall of the right atrium of the heart.
Explanation:
The sinoatrial node (SA), consisting of spindle-shaped cells, initiates the electrical activity of the heart. From its location in the right atrium in proximity to the superior vena cava, the electrical activity spreads to the atria, whose cells are larger than those of the SA.
<u><em>The nitrogenous base</em></u> is the central information carrying part of the nucleotide structure. These molecules, which have different exposed functional groups, have differing abilities to interact with each other.
<u><em>The second portion of the nucleotide is the sugar.</em></u> Regardless of the nucleotide, the sugar is always the same. The difference is between DNA and RNA. In DNA, the 5-carbon sugar is deoxyribose, while in RNA, the 5-carbon sugar is ribose. This gives genetic molecules their names; the full name of DNA is deoxyribonucleic acid, and RNA is ribonucleic acid.
<u><em>The last part of nucleotide structure, the phosphate group</em></u>, is probably familiar from another important molecule ATP. Adenosine triphosphate, or ATP, is the energy molecule that most life on Earth relies upon to store and transfer energy between reactions. ATP contains three phosphate groups, which can store a lot of energy in their bonds. Unlike ATP, the bonds formed within a nucleotide are known as phosphodiester bonds, because they happen between the phosphate group and the sugar molecule.
<span>Adenosine triphosphate, ATP</span>
