Q) Using named examples, describe the functions of proteins in membranes
Main points | |
Key idea: | Structural function |
E.g. Integrin, transmembrane protein · Attach cell to fibres of extracellular matrix - stabilize + maintain shape of cell | |
Key idea: | Transport of substance a/x membrane |
E.g. glucose carriers, ion channels · Regulate transport of large polar sub, ions which cannot cross membr by simple diffusion · Ref: phospholipid bilayer (hydrophobic core) of cell surf membr E.g. Na+/K+ pump · Active transport of Na+/K+ a/x membr - to maintain resting potential (-70mV) of neurone · Ref: energy from ATP + against conc gradient | |
Key idea: | Cell communication with external environment |
E.g. ion channel-linked receptors at post synaptic membr · Binds to acetylcholine for synaptic transmission · Protein receptors for cell to respond appropriately to extracellular signal mol E.g. Adenylate cyclase, embedded in cell membr · Catalyzes ATP to cAMP · Second messenger, cAMP, activates transduction pathways, for cellular responses to signal mol (e.g. glucagon) bound to cell surface receptors | |
Key idea: | Cell recognition and adhesion |
E.g. Cadherins · Transmembrane proteins for cell adhesion during tissue formation | |
Key idea: | Energy transducer |
E.g. Electron carriers · Arranged in sequential manner, at inner mitoch membr or thylakoid membr (chloroplast) for transfer of electrons throu ETC · Energy released during transfer,use to transport protons into intermembr space or thylakoid thus establish proton gradient a/x membr (i.e. proton motive force) E.g. ATP synthase embedded in membr · Flow of proton down conc gradient for ATP syn (chemiosmosis) | |
Comments: (i) Visualize the answer with the aid of a labelled cross section of the cell membrane (ii) Verbalize the answer + write down the main points w/o referring to the answer (use abbreviations) (iii) Read again within the next 24h & once more within 72h (do not spend more than 10min) (iv) 8 named examples w elaboration provided easily exceed the maximum marks | |
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