Chapter 8 out line - CHAPTER 8 Membrane Structure and...

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon
CHAPTER 8 Membrane Structure and Function
Background image of page 1

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

View Full DocumentRight Arrow Icon
Membrane Structure Membranes are fluid fluid Membranes are mosaics of structure and function Membrane carbohydrates are important for cell-cell recognition cell-cell recognition
Background image of page 2
Traffic Across Membranes Membrane’s molecular organization results in selective permeability selective permeability Passive transport is diffusion diffusion across a membrane Osmosis Osmosis is the passive transport of water Cell survival depends on balancing water balancing water uptake and loss Specific proteins facilitate proteins facilitate the passive transport of water and selected solutes Active transport Active transport is the pumping of solutes against their gradients Some ion pumps generate voltage voltage across membranes In cotransport cotransport, a membrane protein couples the transport of two solutes Exocytosis and endocytosis Exocytosis and endocytosis transport large
Background image of page 3

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

View Full DocumentRight Arrow Icon
The Plasma Membrane The plasma membrane is the boundary boundary that separates the living cell from its nonliving surroundings. The plasma membrane controls traffic controls traffic into and out of the cell it surrounds. Exhibits selective permeability selective permeability, allowing some substances to cross it more easily than others.
Background image of page 4
Membrane Structure What makes up membranes? Lipids, proteins, and carbohydrates. Lipids, proteins, and carbohydrates. Most abundant lipid in most membranes are phospholipids. phospholipids. Amphipathic Molecule Amphipathic Molecule – has both a hydrophilic region and a hydrophilic region. (ex. Phospholipids)
Background image of page 5

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

View Full DocumentRight Arrow Icon
Membrane Models Scientists began building molecular models of the membrane before membranes were even seen with the electron microscope in the 1950s. In 1985, Charles Overton Charles Overton hypothesized that membranes are made of lipids based on his observations that substances that dissolve in lipids enter the cells must more faster than substances that are insoluble in lipids. In 1917, Irving Langmuir Irving Langmuir made artificial membranes by adding phospholipids dissolved in benzene to water. In 1925, Dutch scientists , E. Gorter and F. Grendel , E. Gorter and F. Grendel reasoned that cell membranes must actually be phospholipid bilayers, two molecules thick. A bilayer like this could exist as a stable boundary between two aqueous compartments because the molecular arrangement shelters the hydrophobic tails of the phospholipids from water while exposing the hydrophilic heads to water.
Background image of page 6
Continued… Although the heads of phospholipids are hydrophilic, hydrophilic, the surface of an artificial membrane consisting of a phospholipid bilayer adheres less strongly to water than does the surface of an actual biological membrane.
Background image of page 7

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

View Full DocumentRight Arrow Icon
Image of page 8
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/02/2009 for the course SCI 90210 taught by Professor Durkka during the Spring '09 term at École Normale Supérieure.

Page1 / 38

Chapter 8 out line - CHAPTER 8 Membrane Structure and...

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online