BIO 211 Lecture Notes - Lecture 8: Gynoecium, Melatonin, Gonad
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Class notes: direct communication from the inside o one cell occurs through gap junctions. Messenger molecules: stimulate cells if the molecules bind to receptor proteins in or on the cell. This type of communication is fast, but short range. A cell will only be affected by a hormone if it has receptors specific to that hormone. If not, there is no effect: three classes of endocrine hormones. Amino acid based hormones: synthesized from single aa. Peptide hormones: made from chains of amino acids. Steroid hormones: made from cholesterol: target cell receptors: different classes of hormones bind to receptors in different ways based on chemical makeup. Most peptide and amino acid hormones are water soluble; so use cell membrane receptors (cannot penetrate cell membrane). First messenger hormone binds to cell membrane receptor, which activates the formation of the second messenger in the cell. The second messenger activates enzymes that produce cell effects: steroid hormones: can easily penetrate cell membrane.