Lecture 3: Cell Biology PDF

Three basic parts of the cell Plasma membrane serves as a barrier between the cell's contents it'senvironmen cytoplasm contains the cell's organelles performms the cell's function Nucleus Enromosomes structural DNA arrangement The plasma membrane consists p...

Three basic parts of the cell Plasma membrane serves as a barrier between the cell's contents it'senvironmen cytoplasm contains the cell's organelles performms the cell's function Nucleus Enromosomes structural DNA arrangement The plasma membrane consists primarily of a phospholipidbilayer Lipids of the plasmamembrane unsaturatedfattyacid tails in the phospholipidsresponsiblefor the fuidityof the membrane Cholesterol scatteredwithin strengthen andstabilize themembrane at different IBffffTids have carbohydrates facingtheinterstitialfluid attached to the lipid and aid the cell in Interacting withitsevironment Proteins of theplasmamembrane Integral proteins are foundinserted in the lipid bilayer may potrude out of one or both sides Peripheral proteins are loosleyattached to the integral proteins or membrane lipids Glycogen and Carbohydrates facing interstitial fluid attached to the protein and aid the cell in interactingwith itsenvironment I MIIEer.FI anTEfmmttEwithin their layer of thebilayer materialscannotflit to anotherbilayer withoutthehelpof anenzym Allows molecules to movewhereneeded Regulating Membranefluidity Effectoftemperature temperature is kinetic energy Effect of fatty acid saturation saturated vs unsaturated phospholipid tails Effect of Cholesterol The Plasma membrane purposemultifold The glycocalyx combined sugarcoting from the glycolipids and glycoproteins thatserve as mechanism ofcommunication between the cellandits environment Everyone's glycocalyx is unique to the individual exept identicaltwins Functions of the lipid bilayer Its hydrophobic interior serves as a physicalbarrier to watersoluble substance Selectively permeable ions nutrients waste molecules maintains an electrochemical gradientbetween the cytosol and mfffypfys.ie contains receptors that allowcommunicationbetween the cell surrounding environment includingothercells  Diffusion spreadevenlythroughout environment Tendency of molecules or ions to seavenly ought through throughouttheenvironment If continued unopposed will reach equilibrium evendistribution Rate of diffusion steepness of gradient reflectsthe differencebetweenthe concentrations of a substance in 2 areas Steeper the gradientfaster the rate Temperature Reflects KE of a substance Highertemperature mcmovement Easter rate of diffusion  Types of movement simplediffusionmovement of thpolar and lipid soluble substances across the lipidbilayer do not require a transport protein cannot be regulateddependent on concentration gradients Facilitateddiffusion movement of polar and watersolublesubstances throughlipid bilayer downtheir concentrationgradients usingatransportprotein oving Channelmediateddiffusion open allthetime gyppy qq.ggygggppggygpygyngg gagga movement of small Pear molecules a carrierprotein by that undergoes a conformation change in response to bending its substrate Active Transport or ions carrier molecule using a GEEETE.fi nggesgradient the concentration transport protein requiresenergy via the hydrolysis of ATP to move solutes against their concentration gradient Secondary Active transport transportprotein takes advantage of potentialenergy createdby a primary activetransport to move solutes against their concentration gradient membranePermeability Permeable membrane allowspassage of substance Impermeable membranedisallowspassage of substance selectivelyPermeable membrane is permeable to someparticles and impermeable to otherparticles Theplasmamembrane is selectivelypermiable Osmosis diffusion of water osmosis is the movement of a water through a selectively permiable membrane permiableto 1substancenotother H2o moves down its concentration gradient to an area of highersolute concentration Aquaporins Proteinchannels that facilitatewatermovement assa membrane Passingbetweenthe phospholipids H2omolecules are small enough to slit between phospholipids only polar molecule to passthrough lipid bilayer Osmotic Pressure Tonicity ability of a solution to cause a cell to gain or loses water and change the pressure or volume by osmosis Transportproteins are specific  use ATP tocause movement SNARES promotethe dockingfusion ofvesicles to correctdestination 3 uniquepathways for various protein types Transportvesicles carryingsecreted proteinmerge withthe plasma membrane contents are released into interstitial fluid Transportvesicles embeddede with proteins will merge with plasm Meshesbut thHymes are retained in the cytoplasmas lysosomes