BIOL 3510 1st Edition Lecture 18 Outline of Last Lecture I Secondary Pathways II Osteogensis imperfecta III Golgi networks IV Exocytosis V Endocytosis Outline of Current Lecture I Cell Signaling II Four Basic Types of Cell Signaling III Timing of a Cell s Response IV Steroid and thyroid hormones Current Lecture Cell signaling 1 Signaling cells produce signaling molecules All types of macromolecules and their building blocks can be signaling molecules 2 Target cells detect the signal using a receptor protein 3 Signal transduction extracellular signal is converted to an intracellular signal Four basic types of cell signaling 1 Endocrine signals hormones are secreted by endocrine cells into the bloodstream or sap Long range signaling 2 Paracrine signals diffuse in the extracellular fluid and act as local mediators If the secreting cell itself responds autocrine signaling Neighborhood or self signaling 3 Synaptic signal neurotransmitter is delivered to a specific target cell at the synapse Direct signaling 4 Contact dependent the signaling and target cells are in direct physical contact The signaling molecule is not released by the signaling cell 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 What determines the response of a cell to a signal 1 Presence or absence of the receptor 2 Presence or absence of intracellular signaling molecules and intracellular effector proteins Lead to change in gene expression metabolism movement shape status 3 Combinations of signals give different responses Different cells types responde to acetylcholine differently Combinations of signals produce different effects Timing of a Cell s Response Fast change in protein activity Slow change in gene expression cell growth and division Extra cellular signaling molecules can bind cell surface receptors or intracellular receptors Some hormones cross the plasma membrane and bind intracellularly Steroid and thyroid hormones hydrophobic molecules that bind nuclear recptors promoting transcription Steroid hormones cortisol estradiol testosterone Thyroid hormone thyroxine Cortisol is a steroid hormone produced in the adrenal gland in response to stress Some gases diffuse across the plasma membrane and bind intracellularly Nearby nerve endings release acetylcholine triggering the production of nitric acid Diffusion of nitric acid from the endothelial cells promotes relaxation of adjoining smooth muscle cells Binding of an extracellular signaling molecule to a receptor can result in a variety of cellular responses Intracellular signaling molecules form an intracellular signaling pathway Intracellular signaling proteins are molecular switches
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