Which of the following is NOT a characteristic of steroid hormones?

Steroid hormones are unique in their structure and function compared to other types of hormones. One of the defining characteristics of steroid hormones is that they are synthesized from cholesterol, which serves as the precursor. This allows them to be lipid-soluble, enabling them to easily cross cell membranes, which are composed of lipid bilayers. Once inside the target cells, steroid hormones interact with specific receptors and can alter gene expression, leading to changes in protein synthesis and cellular activity.

In contrast, hormones that are built from amino acids, such as peptide hormones, operate differently. They are typically water-soluble and cannot easily pass through the lipid membrane without specific receptor-mediated processes. This distinction is crucial, as it relates directly to how different types of hormones function and exert their effects within the body. Therefore, stating that steroid hormones are built from amino acids does not align with their true biochemical nature and is the rationale behind identifying it as the correct answer to the question.