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Lecture Notes_Passive Transportation_thru_Pseudogenes

Lecture Notes_Passive Transportation_thru_Pseudogenes -...

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9/29 ? Passive Transportation- Movement of molecules across the plasma membrane from high-low concentration areas (across the concentration gradient) Diffuse Freely- O2, H2O, CO2, EthOH, Steroids Osmosis – Diffusion of H2O Facilitated diffusion- Movement of polar molecules and ions down conectration gradient by transmembrane proteins Gated Channels – Allows mass ion movement Opens in response to a stimulus 4 stimuli that open gated channels: Ligand-gated – Ligand (a small signaling molecule) is not actually the thing being transported Mechanically gated – Voltage gated – Light gated – Carrier Proteins – Move specific molecules across plasma membrane Active Transport – Movement of ions or molecules against concentration gradient Requires ATP Electrogenic pump – Transport protein that generates voltage across a plasma membrane Example – proton pump Electrochemical Gradient – Combination of concentration and electrical gradient Direct Active Transport – Uses ATP to directly move molecules of ions Example - Na/K ATPase
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H/K ATPase Ca ATPase ABC transporters/ ATP Binding Cassette Indirect Active Transport – Uses downhill flow of ion to move intended molecule against concentration gradient
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10/2/06 Cell Signalling: 3 Types of Signals – Endocrine Signals Long Distance/Hormonal Paracrine Neighbor cell signaling Autocrine Self signaling Example – tells itself to divide Signal transduction pathway – Stepwise process by which a signal is concerted into a specific cellular response Allows the cell to respond to cues 3 Stages – 1) Reception – a. External – Binding of signal proteins at cell surface b. Internal – movement of signal molecules (steroids, NO) across plasma membrane 2) Transduction – Conversion of signal into a pathway of relay molecules that brings about cellular response - Phosphoralation cascade – + series of phosphorylation events a. turned on by protein kinases b. turned off by protein phosphatases - Secondary Messengers + small, non0protein molecules that may be the messenger of the cell Ex – cAMP, IP3, Calmodulin 3) Response (ex – change metabolism of cell, change charge across membrane) Types: 1) Immediate change in the metabolism of the cell 2) Immediate change in electrical charge across the plasma membrane 3) Change in gene expression within the cell Specific Important Receptors – Internal – Steroid Receptors: Found in the cytosol or nucleus - Glucocortitcoids: blood sugar levels - Sex hormones - Mineralocorticoids: blood pressure level NO Receptors: NO is active and consumed upon entering the cell
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