BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Steroid hormones are believed to enter cells solely by free diffusion through the plasma membrane. However, recent studies suggest the existence of cellular uptake pathways for carrier-bound steroids.

Detailed explanation-2: -Nonsteroid hormones generally cannot pass through the cell membrane of their target cells. Nonsteroid hormones bind to receptors in a target cell and cause the release of secondary messengers that affect cell activities.

Detailed explanation-3: -Chemically, hormones may be classified as either proteins or steroids. All of the hormones in the human body, except the sex hormones and those from the adrenal cortex, are proteins or protein derivatives.

Detailed explanation-4: -Hormones are derived from amino acids or lipids. Amine hormones originate from the amino acids tryptophan or tyrosine. Larger amino acid hormones include peptides and protein hormones. Steroid hormones are derived from cholesterol.