Cell membrane transduction 1

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Cell membrane transport systems hormons action

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  • The carbohydrates are not inserted into the membrane -- they are too hydrophilic for that. They are attached to embedded proteins -- glycoproteins.
  • Signal transduction - transmitting a signal from outside the cell to the cell nucleus, like receiving a hormone which triggers a receptor on the inside of the cell that then signals to the nucleus that a protein must be made.
  • The four human blood groups (A, B, AB, and O) differ in the external carbohydrates on red blood cells.
  • Donuts! Each transport protein is specific as to the substances that it will translocate (move). For example, the glucose transport protein in the liver will carry glucose from the blood to the cytoplasm, but not fructose, its structural isomer. Some transport proteins have a hydrophilic channel that certain molecules or ions can use as a tunnel through the membrane -- simply provide corridors allowing a specific molecule or ion to cross the membrane. These channel proteins allow fast transport. For example, water channel proteins, aquaporins , facilitate massive amounts of diffusion.
  • Cell membrane transduction 1

    1. 1. Cell MembraneCell Membrane Transport systemsTransport systems
    2. 2. OverviewOverview  Cell membraneCell membrane separatesseparates living cell from nonlivingliving cell from nonliving surroundingssurroundings – thin barrier = 8nm thickthin barrier = 8nm thick  Controls traffic in & out of the cellControls traffic in & out of the cell – selectively permeableselectively permeable – allows some substances to cross more easily thanallows some substances to cross more easily than othersothers  Made ofMade of phospholipidsphospholipids,, proteinsproteins & other macromolecules& other macromolecules  Provide:Provide: 1. Fluidity1. Fluidity 2. Asymmetry2. Asymmetry 3. Formed closed compartments3. Formed closed compartments
    3. 3. Chemical compositionChemical composition  Lipids – about 60%Lipids – about 60%  Proteins – about 40%Proteins – about 40%  Carbohydrates – about 1-3%Carbohydrates – about 1-3%  Water and minerals – very smallWater and minerals – very small amountamount
    4. 4. Membrane fat compositionMembrane fat composition variesvaries Fat composition affects flexibilityFat composition affects flexibility – membrane must be fluid & flexiblemembrane must be fluid & flexible  about as fluid as thick salad oilabout as fluid as thick salad oil – % unsaturated fatty acids in phospholipids% unsaturated fatty acids in phospholipids  keep membrane less viscouskeep membrane less viscous  cold-adapted organisms, like winter wheatcold-adapted organisms, like winter wheat – increase % in autumnincrease % in autumn – cholesterol in membranecholesterol in membrane
    5. 5. Membrane ProteinsMembrane Proteins  Proteins determine membrane’s specific functionsProteins determine membrane’s specific functions – cell membrane & organelle membranes each havecell membrane & organelle membranes each have unique collections of proteinsunique collections of proteins  Membrane proteins:Membrane proteins: – peripheral proteinsperipheral proteins  loosely bound to surface of membraneloosely bound to surface of membrane  cell surface identity marker (cell surface identity marker (antigensantigens)) – integral proteinsintegral proteins  penetrate lipid bilayer, usually across whole membranepenetrate lipid bilayer, usually across whole membrane  transmembranetransmembrane proteinprotein  transport proteinstransport proteins – channels, permeases (pumps)channels, permeases (pumps)
    6. 6. Membrane ProteinsMembrane Proteins  Membrane phospholipids act as aMembrane phospholipids act as a solvent for membrane proteinssolvent for membrane proteins  Integral (intrinsic)Integral (intrinsic) – Most membrane proteins are integralMost membrane proteins are integral components of the membrane (70%)components of the membrane (70%) – Penetrate the matrix from the outerPenetrate the matrix from the outer surface to the inner surfacesurface to the inner surface
    7. 7. AP Biology Membrane is a collage of proteins & other molecules embedded in the fluid matrix of the lipid bilayer Extracellular fluid Cholesterol Cytoplasm Glycolipid Transmembrane proteins Filaments of cytoskeleton Peripheral protein Glycoprotein Phospholipids
    8. 8. Functions of membraneFunctions of membrane proteinsproteins  TransportTransport  StructureStructure  ReceptorsReceptors  EnzymesEnzymes  AntigensAntigens
    9. 9. Many Functions of Membrane ProteinsMany Functions of Membrane Proteins Outside Plasma membrane Inside Transporter Cell surface receptor Enzyme activity Cell surface identity marker Attachment to the cytoskeleton Cell adhesion
    10. 10. MembraneMembrane carbohydratescarbohydrates Play a key role inPlay a key role in cell-cell recognitioncell-cell recognition – ability of a cell to distinguish one cell fromability of a cell to distinguish one cell from anotheranother  antigensantigens – important in organ &important in organ & tissue developmenttissue development – basis for rejection ofbasis for rejection of foreign cells byforeign cells by immune systemimmune system
    11. 11. Transport AcrossTransport Across MembranesMembranes  11. Macrotransport. Macrotransport  2. Microtransport2. Microtransport
    12. 12. AP Biology Macrotransport  Moving large molecules into & out of cell  through vesicles & vacuoles  endocytosis  phagocytosis = “cellular eating”  pinocytosis = “cellular drinking”  exocytosis exocytosis
    13. 13. AP Biology Endocytosis phagocytosis pinocytosis receptor-mediated endocytosis fuse with lysosome for digestion non-specific process triggered by molecular signal
    14. 14. MicrotransportMicrotransport  1. Passive1. Passive  2. Active2. Active
    15. 15. Passive transportPassive transport  1. Simple diffusion1. Simple diffusion  2. Facilitated diffusion2. Facilitated diffusion
    16. 16. Simple diffusionSimple diffusion  Movement of molecules in response to aMovement of molecules in response to a concentration gradient.concentration gradient.  It doesn’t need energyIt doesn’t need energy
    17. 17. AP Biology Facilitated Diffusion  Diffusion through protein channels (permeases)  channels move specific molecules across cell membrane  no energy needed  Movable  Immovable “The Bouncer”“The Bouncer” open channel = fast transport facilitated = with help high low
    18. 18. Mechanism of the FacilitatedMechanism of the Facilitated diffusiondiffusion
    19. 19. Active transportActive transport  Occurs against a concentrationOccurs against a concentration gradient and so it requiresgradient and so it requires energy.energy.  1. Primary1. Primary  2. Secondary2. Secondary
    20. 20. Primary active transportPrimary active transport  This is transportation of the ionsThis is transportation of the ions by the help of special enzymaticby the help of special enzymatic transport systems (ATP-ases)transport systems (ATP-ases)  Na K – ATP-aseNa K – ATP-ase
    21. 21. Secondary active transportSecondary active transport  This is transportation of the moleculesThis is transportation of the molecules by the help of electro- chemicalby the help of electro- chemical potential of some ions (Na, H).potential of some ions (Na, H).  1. Symport systems move 2 molecules1. Symport systems move 2 molecules in the same directionin the same direction  2. Antiport systems move 2 molecules2. Antiport systems move 2 molecules in the opposite directionin the opposite direction
    22. 22. Highest level – nervous system Intermediate - hormonal regulation Intracellular (enzymes) Levels of the homeostasis regulation
    23. 23. 2424
    24. 24. SYNTHESIS OF SIGNALLING MOLECULES RELEASE OF SIGNALLING MOLECULES TRANSPORT OF SIGNAL TO TARGET CELLS DETECTION & BINDING OF SIGNAL BY SPECIFIC RECEPTOR CHANGES DUE TO RECEPTOR-SIGNAL COMPLEX SIGNAL REMOVAL & RESPNOSE TERMINATION STEPS IN CELL SIGNALINGSTEPS IN CELL SIGNALING 2525
    25. 25. CLASSIFICATION OF INTERCELLULAR COMMUNICATION Intercellular signaling is subdivided into the following classifications: Autocrine signals target the cell itself. Sometimes autocrine cells can target cells close by if they are the same type of cell as the emitting cell. An example of this are immune cells. Paracrine signals target cells in the vicinity of the emitting cell. neurotransmitters represent an example. Endocrine signals target distant cells. Endocrine cells produce hormones that travel through the blood to reach all parts of the body. Juxtacrine signals target adjacent (touching) cells. These signals are transmitted along cell membranes via protein or lipid components integral to the membrane and are capable of affecting either the emitting cell or cells immediately adjacent. 2626
    26. 26. 2727
    27. 27. 2828
    28. 28. 2929
    29. 29. JUXTACRINE SIGNALINGJUXTACRINE SIGNALING MEMBRANE-ANCHOREDMEMBRANE-ANCHORED LIGANDSLIGANDS NEIGHBOURING CELLS 3030  e.g.*Notch signalling.
    30. 30. Hormones – organic biologically active compounds of different chemical nature that are produced by the endocrine glands, enter directly into blood and accomplish humoral regulation of the metabolism of compounds and functions on the organism level. Hormonoids (tissue hormones) – compounds that are produced not in glands but in different tissues and regulate metabolic processes on the local level, but some of them (serotonin, acetylcholine) enters blood and regulate processes on the organism level.
    31. 31. Specific stimulus for hormones secretion is: -nervous impulse -concentration of the certain compound in blood passing through the endocrine gland
    32. 32. 3333
    33. 33. Membrane receptors To receive and pass on chemical or physical signals, cells are equipped with receptor proteins. Membrane-located receptors can be divided into three parts, which have different tasks. 1. The receptor domain reacts specifically to a given signal 2. The effector domain of the receptor is usually separated by a membrane, a mechanism for signal transfer between the domains is needed. 3. By binding or interconversion, many receptors activate special mediator proteins, which then trigger a signal cascade Other receptors function as ion channels. This is particularly widespread in receptors for neurotransmitters
    34. 34. Metabotropic receptor’s action
    35. 35. 3737
    36. 36. Ion channels Ion channels facilitate the diffusion of ions through biological membranes. Some ion channels open and close depending on the membrane potential  (voltage-gated channels, A)  in response to specific ligands (ligandgated channels, B).

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