Chapter 7 BIO 117 Notes.docx

Chapter 7 BIO 117 Notes.docx - PlasmaMembrane...

Info icon This preview shows pages 1–3. Sign up to view the full content.

Plasma Membrane   Cell membranes are Selectively Permeable-  Allow some substances to cross  easier than others   Phospholipids structure allow for the membrane to function  Amphipathic - Has a hydrophilic  and Hydrophobic region, i.e.  phospholipids  Other types of membrane molecules can also be amphipathic, membrane  proteins are mostly amphipathic with hydrophobic portions sheltered and  hydrophilic portions happy   Membranes are fluid  mosaics  Phospholipids switch places side to side (laterally) only . at 10^7 times per  second   Proteins can move laterally but cannot flip like phospholipids cant either  Lipids and proteins can shift sideways like elbowing through a party  Fluid Mosaic Model    Membrane is Fluid due to weak hydrophobic interactions  Water, glucose and hydrogen ions are examples of things that cannot pass  rapidly through the membrane  Proteins are varied in form and functions and form the Mosaic   Some membrane proteins drift among the membrane and some are static  dependent on the attachments to transport proteins or the extra cellular matrix  Membrane remains fluid with temperature changes as long as the lipids do  not solidify like grease in a bacon pan  Temperature at which a membrane solidifies depends on the lipids  composing it   Membranes that have many unsaturated hydrocarbon phospholipid tails  maintain fluidity as temperature decreases   Number of unsaturated tail compounds in a membrane correspond with the  fluidity response to temperature  Cholesterol is a fluidity buffer mostly found in animals (plants use related  steroid lipids)  As fluidity increases cholesterol restrains movement of phospholipids and as temperature decreases cholesterol hinders close packing of phospholipids  Fluidity must be just right to work with enzymes and functions in the  permeability    
Image of page 1

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

  Membrane Structure   Variations in lipid composition are important to evolution  By making hydrocarbon tails shorter you can increase fluidity   Organism in extreme cold or heat have been observed to have more  unsaturated hydrocarbons   Some  organisms can change their membrane composition such as Bacteria  and Archaea  Membrane Proteins   2 Major types of membrane proteins are Integral and Peripheral  Integral- Permeates hydrophobic inter portion of membrane, Hydrophobic  regions are composed of structures of non polar amino acids (20-30) usually  alpha helices 
Image of page 2
Image of page 3
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