Smooth ER<span>, by contrast, is not associated with </span>ribosomes<span>, and its </span>functions<span> differ. The </span>smooth ER<span> is involved in the synthesis of lipids, including cholesterol and phospholipids, which are used in the production of </span>new<span> cellular membrane.</span>
B. Subgroups
<span>When constructing a dichotomous key, the first step is to look at the group of objects or organisms and separate them into two groups based on a single distinguishing characteristic. Then continue to separate each of the groups until each object has its own separate set of characteristics.</span>
