Cell Biology

... from active transport to vesicles

ion channels

Ion channels undergo a conformational change – an alteration of 3D shape – when coupled with a neurotransmitter (n-t). This conformational change of the protein subunits enlarges the channel pore, permitting entry of ions to the interior of the cell.

The cell membrane comprises a phospolipid bilayer membrane with hydrophobic ends oriented toward the abutting phospholipid molecule. image - cell membrane cross-section : animation - phospholipid : image - bilayer of phospholipids in aqueous solution.

The hydrophilic ends of the two layers are oriented toward the exterior or toward the cell's cytoplasm. Various proteins, including the subunits of ion channels, are embedded in the membrane. ball-stick - globular proteins in phospholipid bilayer : ball-stick - ion channel proteins : animation - facilitated diffusion.

• A • adhesion • C • cell membranescellular adhesion moleculescellular signal transductioncentrioleschemotaxischloroplastcilia & flagellacommunicationconcentration gradientscytokine receptorscytoplasmcytoskeleton • E • energy transducersendoplasmic reticulumendosomesexosome • F • flagella & cilia • G • Golgi apparatusGPCRs • H • hormones • I • ion channels • L • lysosome • M • meiosismicrotubulesmitosismitochondrion • N • Nitric Oxideneurotransmissionneuronal interconnectionsnuclear membranenuclear pore • P • pinocytosisproteasomepumps • R • receptor proteinsreceptor-mediated endocytosis • S • second messengerssignaling gradientssignal transductionspindlestructure • T • transporttwo-component systems • V • vacuolevesicle

Los Alamos National Laboratory (LANL): Scientists propose new method for studying ion channel kinetics: "Faulty ion channels in humans have been shown to cause severe diseases like cystic fibrosis and diabetes and more subtle, but still dangerous physiological effects, like over-responses to general anesthetics. "Ions such as calcium, sodium and potassium play a fundamental role in nearly all biological processes. Calcium, for example, is important in fertilization, cell death, cell division, human hearing, memory, vision, and the immune system. It also plays a factor in cancer, Alzheimer's, alcohol caused neuronal damage, migraine headaches, cardiomyopathy (heart failure), hypertension and a host of other normal and abnormal physiological functions. Other ions and ion channels are important for processes such as muscle contraction and nerve conduction.""

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