Question

Hormones can be:

a) Proteins/peptides (e.g., insulin, growth hormone)
b) Lipid derivatives - derived from cholesterol or fatty acids (e.g., steroids, eicosanoids)
c) Amino acid derivatives - derived from tyrosine or tryptophan (e.g., epinephrine, melatonin, thyroid hormones)
d) Nucleic acid derivatives - derived from DNA or RNA bases

Answer 1

Hormones are categorized into three main types: lipid-derived, amino acid-derived, and peptide hormones. Lipid-derived hormones can cross cell membranes and have cytoplasmic receptors, while amino acid-derived and peptide hormones bind to cell surface receptors. The correct option is b.

Step-by-step explanation:

Hormones within the human body are primarily classified into three key types based on their chemical structure and properties: lipid-derived hormones, amino acid-derived hormones, and peptide hormones.

Lipid-derived hormones, such as estrogen and testosterone, are non-polar molecules that are able to diffuse across cell membranes due to their lipid solubility. Most of these are synthesized from cholesterol.

Their receptors are typically located within the cytoplasm of target cells. Amino acid-derived hormones, such as epinephrine and melatonin, are generally small molecules originating from the amino acids tyrosine and tryptophan. These cannot diffuse through cell membranes and thus bind to receptors on the cell's surface.

Lastly, peptide hormones, like insulin and oxytocin, are composed of long chains of amino acids and are water-soluble. They also operate by binding to cell surface receptors as they cannot traverse the plasma membrane. The correct option is b.