week-5-lecture-notes-5.pdf

lOMoARcPSD|43778768 Week 5 - Lecture notes 5 Human Structure and Function (Curtin University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by turkan alnasar (aln...

lOMoARcPSD|43778768 Week 5 - Lecture notes 5 Human Structure and Function (Curtin University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by turkan alnasar ([email protected])  lOMoARcPSD|43778768 HUMB1000 WEEK 5 CELLS ENERGY Plasma membrane  Forms boundaries around cell  Composed of ‘bi-molecules layers = phosolipic molecules’ form the basic structure  Between the ‘phosolipid mol = ‘cholesterol’ mol = gives some rigit to the structure  Has proteins o Integral proteins o Peripheral proteins o (they like ice burgs on the mem just floating) Lipid Bilayer:  Highly impermeable barrier o Charged (polar) o Non-lipid soluble substance Integral proteins  ‘Pores, channels or carriers’, to all these substances (water type substances) to move across the membrane  They are selectively permeable o Some things can be passed through the cell o Or other substances can’t move Permeability factors  Solubility in lipids  Driving force (up or down gradient)  Molecular size Transport: TRANSPORT TYPE DISCRIPTION Primary active transport Moving AGENST gradient (MOVING UP) Passive active transport Substance is moving DOWN gradient 1) Diffusion through the lipid bilayer (lipid sol. If you are a lipid, you can only defuse Sub.) through membrane 2) Diffusion through Ion channels (H2o sol. sub.) Small ion can move through small channels 3) Facilitated diffusion using a carrier (H2o. sol. Can help/assist water sol. Sub. Move through Sub.) Water soluble substance requires ‘transmembrane proteins’ to function as channels or carriers 3 Types of PASSIVE transport: Downloaded by turkan alnasar ([email protected])  lOMoARcPSD|43778768 HUMB1000 WEEK 5 CELLS ENERGY Diffusion through lip biolayer:  Lipid soluble substance  Can diffuse across lipid biolayer « Respiratory gas (Oxy) « Lipids « Urea (waste product) « Small alcohols  A connected gradient is usually the driving force for this type of transport. Water Soluble Substance: « Ions « Small sugars « Amino acids « H2o = Needs ‘Integral membrane protein = To move across cell membrane Small ion (CHANNELS) Water (CHANNELS) Sugar & Amino (FACITATED DIFFUSION)  ‘Concentration’ or ‘electrical’ gradient often driving force for this transport. Facilitated Diffusion: « Facilitated diffusion o Solute binds to specific transporters on one side of the membrane & released on the other side.  Solutes that move o Glucose (out of cell) o Fructose (into cell)  Rates of movement rely/depend on o Steepness of conc. Gradient o Number of transported proteins in membrane (transport maximum) ‘Gated’ Protein Channels: Downloaded by turkan alnasar ([email protected])  lOMoARcPSD|43778768 HUMB1000 WEEK 5 CELLS ENERGY  Some membrane proteins are ion channels  ‘Electrochemical’ gradient often driving force  Ion channel ‘selective & specific’ (will only involve certain substances)  Some channels form by transport pro = ‘continuously open’ but others only open ‘Transiently’ – (GATED)  Transport = faster rate than facilitated diffusion Active transport:  Energy required process o Moves solutes agents concentrated gradient. TYPES OF ACTIVE TRANSPORT DISCRIPTION Primary active transportation Energy derived DIRECTLY from the ATP  Metabolic (ATP HYDROLYSIS)  1 active transport Secondary active Transportation Energy INDIRECTLY from ATP  Cotransport of NA+ / H+  2 active transport Total number of ATP produced per molecule of glucose is approximately 30. 2 x ATP are from glycolysis, 2 x ATP from the citric acid cycle and 28 x ATP from oxidative phosphorylation. 2 x ATP are used up on average by shuttle molecules Downloaded by turkan alnasar ([email protected])  lOMoARcPSD|43778768 HUMB1000 WEEK 5 CELLS ENERGY Membrane transport of complex molecules Exocytosis  Movement of LARGE mol OUT of cells  Occurs in secretory cells  Secretion in vesicles (mem packets) – vesicles fuse with cell mem  Ex – neurotransmitters secretion at the synapse Endocytosis  Movement of large mol & particles INTO cells « PINOCYTOSIS Engulfing small partials & fluids « PHAGOCYTOSIS Engulfing large particles « RECPTOR – MEDIATED ENDOCYTOSIS Movement of spac sub into cells into the ‘caveolae region’ of cell mem Downloaded by turkan alnasar ([email protected])  lOMoARcPSD|43778768 HUMB1000 WEEK 5 CELLS ENERGY OSMOSIS Plasma membrane composition:  H2O mol penetrate mem by diffusion through the lip bilayer or through aquaporins (transmembrane protein) that function as H2O chan  Movement of H2o = osmosis o Movement of H2O from low solute concentration to high solute concentration across a semi- permeable mem. Osmosis driving force - When talking about H2O movement « Concentration of solutes dissolved in it - Water = solvent « High concentration « 56 molar - This means solutes are dissolved in H2O it’s concentration changes very little - When solutes dissolved In H2o = the solution displays a ‘osmotic pressure’ or ‘drawing power to encourage H2O to move towards it. - H2o always moves to the solution with the highest OSM pressure « Highest solute cont - Net movement of H20 through a selectively permeable mem - Os occurs when mem is permeable to H20 but Not certain solutes - Os pressure that a solution exert is proportional to number of osmotically – active particles in solution. Pressure: - Os pressure of a solution is proportional to the concentration of solute particle that cannot cross the mem Tonicity - Measures of solutions ability to change volume of cells by altering their H2O content (amount/volume) Isotonic solution Maintains normal shape Hypotonic solution Undergoes hemolysis – swelling or bursting Hypertonic solution Shrinking, becoming dehydrated – crenation Downloaded by turkan alnasar ([email protected])  lOMoARcPSD|43778768 HUMB1000 WEEK 5 CELLS ENERGY Downloaded by turkan alnasar ([email protected])