BIOL 1201 : Unit 5-Final Study Guide
Document Summary
Nobel prizes 5 in the last 18 years. When epinephrine binds to cardiac (heart) muscle cells, it speeds their contraction. When it binds to muscle cells of the small intestine it slows down their contractions. Why is that: the two types of muscle cells have different signal transductions pathways for epinephrine and thus have different cellular responses. Cell signaling: direct contact, local: paracrine and synaptic signals, distant: hormonal signals. When a platelet contacts a damaged blood vessel, it is stimulated to release thromboxane a2. Thromboxane a2 in turn stimulates vascular spasm and attracts additional platelets to the injured site. A2 is acting as a: local signal molecule. Receptor example: how many radio stations are in this room right now: many (lots of signal molecules but have to have the right receptor) Based on your understanding of membrane permeability, the signal molecules (ligands) binding to cytoplasmic receptors are: non-polar molecules, example: steroids, the signal molecule leptin is 16,000 da protein.
