Cai_Chapter 11 - Chapter 11 Membranes Problems for Chapter...

Info icon This preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 11: Membranes Problems for Chapter 11:  Problems 2, 6, 7, 8, 10,  13, 14, 15, and 19 http://ebooks.bfwpub.com/lehninger5e http://highered.mcgraw-hill.com/sites/0072495855/ student_view0/chapter2/animation__how_the_sodium_ potassium_pump_works.html   1
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
CHAPTER 11 Membranes The function of biological membranes The structure and composition membranes Dynamics of membranes Structure and function of membrane proteins Transport across biological membranes 2 Key topics :
Image of page 2
What are Membranes? Complex lipid-based structures that form pliable sheets Composed of a variety of lipids and proteins Some membrane lipids and proteins are glycosylated All cells have the cell membrane, which separates the cell from its surrounding Eukaryotic cells have various internal membranes that divide the internal space into compartments 3
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Viewed in cross section, all cell membranes share a characteristic trilaminar appearance. This erythrocyte was stained with osmium tetroxide and viewed with an electron microscope. The plasma membrane appears as a three-layer structure, 5 to 8 nm (50 to 80 Å ) thick. The trilaminar image consists of two electron- dense layers (the osmium, bound to the inner and outer surfaces of the membrane) separated by a less dense central region. 4
Image of page 4
5
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
6
Image of page 6
Triacylglycerol storage          Ether lipids Plants? 7
Image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
8
Image of page 8
Common Features of Membranes Sheet-like flexible structure, 30-100 Å (3-10 nm) thick Main structure is composed of two leaflets of lipids ( bilayer ) Except of some archaebacteria: monolayer of bifunctional lipids If they contain the bifunctional lipids, some do not. Form spontaneously in aqueous solution and are stabilized by non-covalent forces, esp. hydrophobic effect Protein molecules span the lipid bilayer Asymmetric Some lipids are found preferably “inside” Some lipids are found preferably “outside” Carbohydrate moieties are always outside the cell Electrically polarized (inside negative ~ -60mV) Fluid structures: 2-dimensional solution of oriented lipids 9
Image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
10
Image of page 10
Functions of Membranes Define the boundaries of the cell Allow import and export Selective import of nutrients (e.g. lactose) Selective export of waste and toxins (e.g. antibiotics) Retain metabolites and ions within the cell Sense external signals and transmit information into the cell Provide compartmentalization within the cell separate energy-producing reactions from energy-consuming ones keep proteolytic enzymes away from important cellular proteins Produce and transmit nerve signals Store energy as a proton gradient and support synthesis of ATP 11
Image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Fluid Mosaic Model of Membranes Proposed in 1972 by Singer and Nicholson (UCSD) Lipids form a viscous, two-dimensional solvent into which proteins are inserted and integrated more or less deeply Both lipids and proteins are capable of lateral and rotational movement within the membrane.
Image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern