Ap bio ch 5 ppt Cell Membranes

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Ap bio ch 5 ppt Cell Membranes Ap bio ch 5 ppt Cell Membranes Presentation Transcript

  • Ch 5 Membrane Structure & Function• Structure• Traffic across – Passive transport • Diffusion • Osmosis • Facilitated diffusion – Active transport – Endo & exocytosis
  • Functions of Membrane Proteins• Transport• Enzyme activity• Signal transduction• Intercellular joining• Cell to cell recognition• Attachment to cytoskeleton
  • Structure of Membrane• Phospholipids & proteins• Fluid mosaic model• Factors that affect fluidity: – Fatty acid type – Temp• Types of proteins – Integral – Peripheral
  • Traffic Across Mem• Selective permeability (ease & rate) depend on 2 things: 1. discriminating barrier of lipid bilayer – Impermeable to larger polar & ions – Perm to nonpolar – How about water?2. Transport proteins
  • Traffic Across MembraneRemember diffusion…
  • Osmosis• Why important?• Relative terms used to compare concentration of inside vs outside of cells – Hypertonic – Hypotonic – Isotonic• Water always moves toward hypertonic• Solutes move from high to low concentration.
  • Animal cells in hypotonic & hypertonic solutions
  • Cells in a hypotonic solution gain water & swell; possiblyburst if no cell wall.Cells in a hypertonic solution lose water & shrink.Cells in an isotonic solution have no net gain or loss ofwater.
  • Osmoregulation – control of water balance• Ex of how orgs stabilize water loss & uptake: – Freshwater paramecium
  • OsmosisEx of how orgsstabilize waterloss & uptake:Marine org - shark
  • Passive transport• Diffusion across a membrane• Requires no energy b/c molecules moving down concentration gradient (H to L)• 3 types – Diffusion – Osmosis – Facilitated diffusion
  • • Diffusion of solutes across membrane w/ Facilitated Diffusion help of proteins – Large polar or ions – proteins • Specific • Can be sat • Can be inhibited – Protein transports solute Cystic Fibrosis by • Changing shape • Selective channels
  • Cystic FibrosisCause:Humans have a gene encoded in their DNA which manufactures a special protein known as CFTR, Cystic Fibrosis Transmembrane Conductance Regulator. This protein controls the flow of chloride ions across the cell membrane.
  • The pumping of solutes against Active Transport their gradient (L to H)• Nonspontaneous• Requires energy (usually ATP)• Maintains steep ionic gradients (potential energy)• Ex: Na/K pump
  • Active transport
  • ActivetransportIon pumps – pump ions across membrane – generate voltage across mem – Electrochemical gradient – combo of concentration gradient & electrical gradient – Na/K pump is ex
  • Endocytosis & Exocytosis• Methods for very large molecules & particles to get into & out of the cell• Requires energy b/c requires movement of the plasma membrane. http://highered.mcgraw-hill.com/olc/dl/120068/bio02.swf Animation, baby!
  • Endocytosis & Exocytosis Exocytosis EndocytosisDefinition Exporting Importing of macromolecules by macromolecules by fusion of vesicles to pm forming vesicles with pmVesicles come Budded from ER or Pm & sinks inward &from Golgi pinches off into cytoplasmUsed to Secrete products - Incorporate insulin extracellular large substances
  • Endocytosis3 types:• Phagocytosis – cell “eating” solid particles (uses pseudopodia)• Pinocytosis – cell “drinking” fluid droplets• Receptor mediated endocytosis – importing specific macromolecules
  • Since cells can’t continue to grow larger,they must split, or divide at some point.
  • Cell Cycle2 parts:• Interphase – period of growth & DNA synthesis (copying)• Mitotic phase – period of cell division (1 cell divides into 2 cells) I love cells, baby!
  • Interphase – time of cell growth & copying of DNA3 phases of interphase:• G1 – growing & ribosomes making proteins• S – synthesis (or copying) of DNA (sister chromatids formed)• G2 – growing & getting ready to divide
  • Cells spend most of their time in interphase. DNA is in chromatin (stringy) form.
  • Mitotic Phase – time of cell divisionConsists of 2 main phases:1. Mitosis – division of nucleus2. Cytokinesis – division of cytoplasm
  • Sister Chromatids• Identical copies of chromosomes attached by a centromere.
  • Mitosis4 phases:• Prophase• Metaphase• Anaphase• Telophase http://www.cellsalive.com/mitosis.htm
  • Prophase• DNA condenses into chromosomes• Nuclear membrane disappears• Centrioles move toward poles• Spindle fibers form & attach to chromosomes
  • Metaphase• Sister chromatids lined up on metaphase plate with spindle fibers attached to them.
  • Anaphase• Sister chromatids get pulled apart to poles as spindle fibers shorten.
  • Telophase• New nuclear membrane forms around chromosomes at each pole• Chromosomes “unpack” into chromatin• Cell membrane begins to pinch in (animals cells) or cell plate develops (plant cells)
  • Cytokinesis – division of the cytoplasm Cell plate Cleavage furrow
  • Control of the Cell Cycle• Enzymes control cell cycle so cells divide at the right times• Cancer – uncontrolled cell division caused by a change in the DNA that codes for the making of the control enzymes
  • Cell Cycle Control• http://wps.prenhall.com/esm_freeman_biosci _1/7/1948/498717.cw/index.html
  • Internal Vs external signals• Internal – the checkpoints• External – growth factors, density dependent inhibition, anchorage dependence
  • cancer• Tumor• Begign• Malignant• Metastasis• Radiation & chemo
  • Cancer• Forms tumors & can spread through body - metastasize
  • Causes of Cancer• Environmental factors• UV radiation from sun• Tobacco• Viral infections• Genetic
  • How to prevent cancer:• Low fat, high fiber diet• Vitamins• Exercise• Don’t smoke• Use sunscreen• Regular doctor appointments
  • Removal of colon polyps• http://www.gihealth.com/flashvideo/flash.html
  • Review of the cell cycle• http://www.c ellsalive.co m/mitosis.ht m