The nitrogenous bases consist of single or double rings, and each ring contains two nitrogens. Paste and label them below. The arrows in Figure 9 point to the single structural difference between ribose and deoxyribose. These are called nucleosides . Paste and label them on the next page.
Nucleosides can combine with one, two or three phosphates .
The greater the number of phosphates, the greater the energy contained in the molecule. Organic molecules are carbon-based, whereas inorganic molecules are not. Each class of macromolecules is built up from subunits. Except for cellulose, they are easily assembled and disassembled. One type of subunit can be converted into another through biochemical reactions in the body.