Nothing Special   »   [go: up one dir, main page]
Scribd Logo
Upload

Welcome to Scribd!

  • 26 views

    Cell Membrane - Slides

    Uploaded by

    Sabrina Teitel
    The document summarizes key aspects of cell membrane structure and function. It describes how the cell membrane is a phospholipid bilayer with embedded proteins. It functions as a selective barrier via transport proteins that use passive diffusion, facilitated diffusion, osmosis, and active transport to regulate what enters and leaves the cell. Active transport requires energy to move molecules against their concentration gradient using protein pumps or coupled with other transport processes. The membrane also uses bulk transport mechanisms like endocytosis and exocytosis to bring larger particles and molecules into and release them from the cell.

    Copyright:

    © All Rights Reserved
    Download as PPT, PDF, TXT or read online from Scribd

    Cell Membrane - Slides

    Uploaded by

    Sabrina Teitel
    26 views39 pages
    The document summarizes key aspects of cell membrane structure and function. It describes how the cell membrane is a phospholipid bilayer with embedded proteins. It functions as a selective barrier via transport proteins that use passive diffusion, facilitated diffusion, osmosis, and active transport to regulate what enters and leaves the cell. Active transport requires energy to move molecules against their concentration gradient using protein pumps or coupled with other transport processes. The membrane also uses bulk transport mechanisms like endocytosis and exocytosis to bring larger particles and molecules into and release them from the cell.

    Original Description:

    Biology 12

    Copyright

    © © All Rights Reserved

    Available Formats

    PPT, PDF, TXT or read online from Scribd

    Did you find this document useful?

    Is this content inappropriate?

    The document summarizes key aspects of cell membrane structure and function. It describes how the cell membrane is a phospholipid bilayer with embedded proteins. It functions as a selective barrier via transport proteins that use passive diffusion, facilitated diffusion, osmosis, and active transport to regulate what enters and leaves the cell. Active transport requires energy to move molecules against their concentration gradient using protein pumps or coupled with other transport processes. The membrane also uses bulk transport mechanisms like endocytosis and exocytosis to bring larger particles and molecules into and release them from the cell.

    Copyright:

    © All Rights Reserved
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    26 views39 pages

    Cell Membrane - Slides

    Uploaded by

    Sabrina Teitel
    The document summarizes key aspects of cell membrane structure and function. It describes how the cell membrane is a phospholipid bilayer with embedded proteins. It functions as a selective barrier via transport proteins that use passive diffusion, facilitated diffusion, osmosis, and active transport to regulate what enters and leaves the cell. Active transport requires energy to move molecules against their concentration gradient using protein pumps or coupled with other transport processes. The membrane also uses bulk transport mechanisms like endocytosis and exocytosis to bring larger particles and molecules into and release them from the cell.

    Copyright:

    © All Rights Reserved
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    of 39

    THE CELL

    MEMBRANE
    SBI4U
    U1: Biochemistry
    Textbook Sections 2.2 and 2.4
    MEMBRANE
    STRUCTURE

    Textbook Section 2.2


    https://www.youtube.com/watch?v=Qqsf_UJcfBc
    Note the kinks in the phospholipid tails.
    Recall this is due to double bonds (unsaturated) and
    increases fluidity
    Note the cell membrane is a bilayer, due to
    spontaneous positioning of the polar and non-polar
    ends of the phospholipids which form it.
    Note structural support of the protein filaments acting like scaffolding –
    giving the cell a shape
    Note also the cholesterol studded here and there on either side of the
    bilayer; it maintains fluidity, preventing the cell from ‘melting’ in heat and
    from becoming too rigid in the cold
    https://www.youtube.com/watch?v=CNbZDcibegY
    In the freeze fracture technique cells are flash frozen in liquid nitrogen,
    dropped from a height, or split with a knife, and gold is evaporated onto
    their exposed surfaces; with the hope that something interesting might
    be visualized on the screen of the scanning electron microscope
    Membrane Proteins
    Membrane Proteins
    FUNCTIONS OF CELL
    MEMBRANE PROTEINS

    Some form "channels" through which


    various substances enter and depart from
    the cell. Enzymes help speed up chemical
    reactions. Some proteins, when attached to
    special chemicals, serve as receptors,
    setting functions such as hormone synthesis
                                                                                                      
    into operation. This attachment launches
    the beginning of a certain function such as
    the synthesis of hormone in the cell. The
    identifiers of the cell are the proteins
    receiving information regarding whether
    other cells in the body are foreign invaders.
    Some proteins assume structural functions;
    others serve as attachment points for cells
    to adhere to one another. Other proteins are
    important in anchoring the cell skeleton.
     Cell-cell recognition is critically important for any kind of organism to function. 
    This job is mainly undertaken by membrane carbohydrates.  In order for cells to
    recognize each other, they bind to molecules found on the cell’s surface, which
    happen to mostly be carbohydrates.  Membrane carbohydrates sometimes bind
    covalently to lipids, forming what is to be called a glycolipid, while the majority
    of membrane carbohydrates are covalently bound to proteins, making the two
    together glycoproteins.  Markers found on the surface of red blood cells, for
    example, and dictate what blood type you are.
    MEMBRANE
    TRANSPORT

    Textbook Section 2.4


    2 Main Categories
    of Membrane Transport
    Outline of Membrane Transport
    Mechanisms
    PASSIVE TRANSPORT ACTIVE TRANSPORT

    1) Diffusion 1) Protein Pumps


    • Simple Diffusion • Primary Active Transport
    • Facilitation Diffusion • Secondary Active Transport

    2) Osmosis 2) Bulk Transport


    • Exocytosis
    • Endocytosis
    o Pinocytosis
    o Phagocytosis
    o Receptor-Mediated Endocytosis
    Passive Transport: Diffusion
    • Diffusion = the movement of molecules from an area of HIGH
    concentration to an area of LOW concentration (ie. movement of
    a substance down its concentration gradient
    2 Types of Diffusion
    Recap: Facilitated diffusion is when an assisting protein remains in
    place and “helps” a molecule across by undergoing a change in shape
    that moves the binding site from one side of the membrane to the
    other. It is still passive since the molecule is still moving down their
    concentration gradient.
    Net Diffusion  Dynamic Equilibrium
    Passive Transport: Osmosis
    Tonicity
    Tonicity
    Tonicity
    Active Transport
    Certain molecules need to be kept in the cell at a concentration that is
    greater than the surrounding environment.
    This requires the expenditure of energy, usually in the form of ATP

     https://www.youtube.com/watch?v=_bPFKDdWlCg
    Proton Pump (active transport)
    Proton pump. By pumping H+ out of the cell with the
    hydrolysis of ATP, proton pumps produce an H+
    gradient and a charge separation called a membrane
    potential. These two forms of potential energy can be
    used to drive active transport of solutes.
    Secondary Active Transport
    Secondary Active Transport
    Coupled Channel (active)
    (Sucrose/Glucose – H+ Symport)
    Active Transport: Bulk Transport
    Endocytosis & Exocytosis
    Exocytosis
    Endocytosis – 3 Types
     Phagocytosis (transport of actual particles), pinocytosis
    (transport of water, along with any solutes in the water),
    and receptor-mediated endocytosis

     In receptor-mediated endocytosis, specific macro molecules outside


    the cell attach to the binding sites of receptor proteins, even if they are
    in low concentrations ex transferrin – the source of blood iron and
    LDL - for membrane cholesterol. These receptors are embedded in
    the plasma membrane in specialized regions called coated pits.
    After the contents of the vesicle are released inside the cell, the
    receptor proteins are reused to form new coated pits.
     Crash Course Recap:
    https://www.youtube.com/watch?v=dPKvHrD1eS4
    Endocytosis 1 – Pinocytosis
    Endocytosis 2 – Phagocytosis
    Endocytosis 3 – Receptor-Mediated Endocytosis
    Exocytosis / Endocytosis – Summary:
     Endocytosis brings molecules into a cell while
    exocytosis takes molecules out of a cell.

     Both processes use vesicles for molecular


    transport.

     Endocytosis creates vesicles while exocytosis


    can destroy them.

     The primary function of endocytosis is getting


    nutrients and the primary function of exocytosis is
    expelling waste.
    Membrane Transport (2.4) – Summary:

    You might also like