Final answer:
The sex hormones of many animals are known as steroids, which are lipid-soluble molecules derived from cholesterol, including estrogen and testosterone. These hormones can cross cell membranes and bind with receptors within cells, playing key roles in bodily functions and having extended half-lives in the blood due to their transport by proteins.
Step-by-step explanation:
The sex hormones of many animals are lipid molecules known as steroids. These hormones, which include estrogen and testosterone, are lipid-soluble and can diffuse across cell membranes because they are derived from cholesterol and are non-polar. Their solubility allows them to travel freely through the bloodstream and interact with receptors inside the target cells. Examples of other steroid hormones are aldosterone and cortisol, which are also derived from cholesterol and share the characteristic of being insoluble in water.
Steroid hormones play a crucial role in regulating various bodily functions, including the development and regulation of the reproductive system and metabolism. Due to their lipid nature, steroid hormones are transported by transport proteins in the blood, which significantly extends their half-life compared to water-soluble hormones, such as epinephrine, an amino acid-derived hormone.