BIOL 1107 1nd Edition Lecture 14 Outline of Last Lecture I Primary Transcription II Initiation a Prokaryotes b Eukaryotes III Splicing IV tRNA Outline of Current Lecture I Cell to Cell Contact II Hormones III Signal Reception IV G Proteins Current Lecture I Cell to Cell Contact Tight junctions seal cells together hold cells together and keep things out o Cannot have tissue without tight junctions o Cells can only hold so many tight junctions because there is only so much room too many tight junctions cause the cell to become too dense Desmosomes connect the cytoskeletons of the cell Gap junctions act as channels between cells direct communications II Hormones A hormone is a small information carrying molecule typically present in minute concentrations It is secreted from a cell Circulates the body Acts on target cells far from the signaling cell III Signal Reception Signal receptors are bound by hormones other cell signals the presence of an appropriate receptor protein dictates which cells will be available to respond to a particular hormone Identical receptors in diverse cells and tissues o Allow long distance signals to coordinate the activities of cells o Throughout a multicellular organism These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute IV G Proteins G proteins are activated when they bind GTP G proteins are deactivated when they hydrolyze the bound GTP to GDP 1 Signal received 2 G protein binds GTP and splits 3 Activated G protein binds to the enzyme producing 2nd messenger
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