CELLS TO ORGANISMS LECTURE NOTES.! BIOL1040 University of Queensland

Transcription

1 CELLS TO ORGANISMS LECTURE NOTES BIOL1040 University f Queensland

2 BIOL1040 Cells t rganisms Lecture Ntes Cntents Mdule 1 Principles f Cell Functin... 2 Lecture 1: Membrane Structure and Functin Lecture 2: Membrane Structure and Functin Lecture 3: Cell Cmmunicatin... 4 Mdule 2 Nervus Systems... 6 Lecture 1: Neural Transmissin Cells and Ins... 6 Lecture 2: Neural Excitability... 8 Lecture 3: Synaptic transmissin... 9 Lecture 4: Neurnal Organisatin Mdule 3 - Supprt + Mvement Lecture 1: Skeletal muscle and mvement Lecture 2: Skeletns Lecture 3: Lcmtin Mdule 4 - Circulatin and Gas Exchange Lecture 1: Circulatry Systems Lecture 2: Bld Vessels Lecture 3: Bld Lecture 4: Gas Exchange Lecture 5: Crdinatin f Circulatry System and Gas Exchange Mdule 5 - Endcrinlgy Lecture 1: Principles f Endcrine Systems Lecture 2: Examples f Endcrine Functin Lecture 3: Hypthalamus and Pituitary Lecture 4: Stress and Adrenaline Mdule 6 - Plant Bilgy Lecture 1: Phtsynthesis Lecture 2: Plant Structure + Develpment Lecture 3: Transprt in Vascular Plants Lecture 4: Plant Respnses t Internal and External Signals (I) Lecture 5: Plant Respnses t Internal and External Signals (II) Lecture 6: Plant Bitechnlgy

3 BIOL1040 Cells t rganisms Lecture Ntes Mdule 1 Principles f Cell Functin Lecture 1: Membrane Structure and Functin 1 FLUID MOSAIC MODEL Phsphlipids = amphipathic hydrphilic head + hydrphbic tail Membrane = phsphlipid bilayer Membrane prteins embedded in bilayer Hydrphbic prtein regins = inside membrane Hydrphilic prtein regins = utside membrane MEMBRANE FLUIDITY Phsphlipid Mvement Lateral mvement tw lipids n same side swap psitin Flip-flp tw lipids n ppsite sides swap psitin Phsphlipid Tail Chemistry Duble bnded kinks unsaturated tails prevent clsely packed arrangement increased fluidity Membrane remains fluid t lwer temperature if it is rich in unsaturated tails Saturated tails clsely packed arrangement decreased fluidity Chlesterl Temperature buffer prevents fluidity changes due t temperature changes Different effects n membrane fluidity at different temperatures Bdy temperature Decreased phsphlipid mvement decreased fluidity Lw temperatures Hinders clse packing decreased temp required fr membrane slidificatin Experiments- Hw d we knw it is a fluid msaic? Labelled prteins f muse and human cells fusin f cells mixed prteins SIX MAJOR FUNCTIONS OF MEMBRANE PROTEINS 1. Transprt 2. Enzymatic activity 3. Signal transductin 4. Cell-t-cell recgnitin 5. Intercellular jining 6. Attachment t cytskeletn and extracellular matrix SELECTIVE PERMEABILITY Membrane structure lipid bilayer selective permeability Permeable t water, xygen, carbn dixide Impermeable t charged ins, glucse, macrmlecules (prteins, RNA) essential 2

4 BIOL1040 Cells t rganisms Lecture Ntes PASSIVE TRANSPORT Diffusin/smsis Des nt require ATP Cncentratin equilibrium eliminatin f gradients Dwn cncentratin gradient (high cncentratin lw cncentratin) OSMOSIS Lecture 2: Membrane Structure and Functin 2 TONICITY ability f a slutin t cause a cell t gain r lse water Istnic slutin equal cncentratins n net mvement f water Hypertnic slutin slute cncentratin greater utside cell cell lses water Hyptnic slutin slute cncentratin greater inside cell cell gains water TRANSPORT PROTEINS Allw mvement f hydrphilic substances acrss membrane (nt lipid sluble) Channel prteins = tunnels Diffusin f water t regin with higher slute cncentratin equal cncentratins Carrier prteins bind t mlecule cnfrmatinal change shuttle acrss membrane Transprt prteins are specific FACILITATED DIFFUSION Passive transprt aided by transprt prteins faster diffusin Channel prteins Aquaprins channel prteins that regulate flw f water In/gated channels pen/clse in respnse t stimulus ACTIVE TRANSPORT Uses ATP Against cncentratin gradient Electrgenic pumps transprt prteins that generate vltage acrss membrane Na + /K + ATPase (sdium ptassium pump) animals Prtn pump plants/fungi/bacteria COTRANSPORT Active transprt f ne slute indirectly drives transprt f anther slute E.g. Sucrse-H+ Ctransprter BULK TRANSPORT Excytsis Neurtransmitter release Endcytsis Phagcytsis cell engulfs particles Pincytsis cell drinks fluids cntaining mlecules Receptr-mediated inward budding f vesicles frmatin f Clathrin-cated vesicles 3

5 BIOL1040 Cells t rganisms Lecture Ntes Lecture 3: Cell Cmmunicatin LOCAL VS LONG DISTANCE SIGNALLING Autcrine signalling cell releases a chemical that affects itself (lcal) Paracrine signalling cell secretes smething that affects nearby cells (lcal) Synaptic signalling neurn releases neurtransmitter int synapse which effects nearby target cell (lcal) Hrmnal signalling hrmne secreted int bld stream, can reach cells anywhere in bdy (lng distance) 3 STAGES OF CELL SIGNALLING Receptin Transductin Respnse 1. Receptin a. Signalling mlecule binds t receptr n cell surface r inside cell b. Hydrphilic signalling mlecules i. Water sluble ii. Mve freely thrugh bld iii. Surface receptrs c. Hydrphbic signalling mlecules i. Lipid sluble ii. Require transprt prteins d. Agnist drug that mimics effect f natural receptr e. Ligand chemical that binds t receptr, first messenger 2. Transductin a. Signal transductin pathway cellular respnse i. Activated receptr mlecule A mlecule B mlecule C leading t a respnse 3. Respnse a. Activatin f a cellular respnse (e.g. Gene transcriptin/ Prtein Prductin) RECEPTOR TYPES Plasma membrane receptrs surface In channel receptrs Fastest (<1s), signalling mlecule binds t receptr and pens an in channel allwing in t mve rapidly dwn cncentratin gradient, neurtransmissin G prtein-cupled receptrs Biggest family, 7 transmembrane dmains Tyrsine kinase linked receptrs Metablism, cell grwth, cell reprductin insulin Intracellular receptrs inside cell Sterid receptrs G prtein-cupled receptrs G prteins prteins that bind GTP Hetertrimeric 3 different peptide chains 7 transmembrane dmains Sequence f events 1. Signalling mlecule binds t receptr 2. Receptr cnfrmatinal change 3. G prtein binds t receptr and is activated 4. Activated G prtein detaches and binds t enzyme 5. Activated enzyme catalyses cnversin f ATP t camp 6. camp (secnd messenger) activates anther enzyme 7. Activated enzyme causes cellular respnse 4

6 BIOL1040 Cells t rganisms Lecture Ntes Respnse depends n target cell Adrenaline Airway cells relaxatin f smth muscle pening f airways asthma treatment Heart cells increase in heart rate camp secnd messenger prduced by activated adenylyl cyclase Orphan GPCR with unknwn signalling mlecule AMPLIFICATION OF SIGNALLING Enzymes active lng enugh t prcess number mlecules f substrate befre they becme inactive again Few enzymes many enzyme prducts TYROSINE-KINASE RECEPTORS Insulin binds t surface receptr phsphrylatin cascade Kinase enzyme that activates a prtein thrugh phsphate transfer (phsphrylatin) Phsphrylatin cascade series f different mlecules in pathway are phsphrylated chain reactin Phsphrylatin prtein cnfrmatinal change STEROID RECEPTORS Intracellular Nucleus genes regulatin prtein prductin cntrl 5