BIOL 3510 1st Edition Lecture 18 Outline of Last Lecture I. Secondary PathwaysII. Osteogensis imperfectaIII. Golgi networksIV. ExocytosisV. EndocytosisOutline of Current Lecture I. Cell SignalingII. Four Basic Types of Cell SignalingIII. Timing of a Cell’s ResponseIV. Steroid and thyroid hormones Current LectureCell 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 signalFour 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 receptor2. 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 divisionExtra 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, testosteroneThyroid hormone: thyroxineCortisol 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
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