Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of...
-
Upload
alberta-lamb -
Category
Documents
-
view
224 -
download
0
Transcript of Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of...
![Page 1: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/1.jpg)
Membrane Structure & Function
Ch. 7
![Page 2: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/2.jpg)
Membrane & Function
Lipid Bilayer Minimizes number of hydrophobic groups exposed to
water Fatty acid tails don’t have to spend energy fighting
water molecules
![Page 3: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/3.jpg)
![Page 4: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/4.jpg)
Fluid Mosaic Model
Mosaic – because cell membranes have a mixed composition (phospholipids, glycoplipids, sterols, proteins)
Fluid – motions and interactions of the parts of the membrane
Hydrophobic interactions in membrane are weaker than covalent bonds
Most phospholipids and some proteins are free to drift sideways
![Page 5: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/5.jpg)
![Page 6: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/6.jpg)
![Page 7: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/7.jpg)
Membrane Proteins
Transport proteins – allow water-soluble substances to move through Bind molecules or ions on one side/release on the other
Receptor proteins – Bind extracellular substances like hormones that change cell activity
Recognition Proteins – “Molecular Fingerprint” Ex: “Self” sign for immune system
Adhesion Proteins – Cells of same type stick together (tissue)
![Page 8: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/8.jpg)
Crossing Cell Membranes
Selective Permeability
Allows some substances to cross, but not others.
Water, oxygen, carbon dioxide, small nonpolar molecules can cross cell membrane
Glucose, ions, other large polar molecules do not move freely across bilayer
![Page 9: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/9.jpg)
Concentration Gradients
Concentration – number of molecules or ions of a substance in a region
Gradient – number in one region is different than in another
Concentration Gradient – difference in number of molecules or ions in two adjoining regions
Things will naturally travel from
high concentration low concentration
![Page 10: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/10.jpg)
Diffusion – movement of like molecules or ions down a concentration gradient (high low)
![Page 11: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/11.jpg)
Factors that influence rate
Steepness of gradient ↑ Diffusion ↑
Temperature ↑ Diffusion ↑
Molecule size ↓ Diffusion ↑
Electric gradient (opposite charges attract)
![Page 12: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/12.jpg)
Osmosis
Osmosis – Diffusion of water due to a water concentration gradient between two regions through a selectively permeable membrane
The side with more solute has a lower water concentration
Hypertonic Solution – more solutes Hypotonic Solution – less solutes Water goes: hypotonic hypertonic Isotonic Solution – solutes the same, no net movement
![Page 13: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/13.jpg)
![Page 14: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/14.jpg)
![Page 15: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/15.jpg)
Protein Mediated Transport
Passive Transport
Transport proteins allow solutes to move both ways across cell membrane
Concentration ↑ binding ↑ transport ↑
Travels from higher concentration to lower concentration until even
![Page 16: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/16.jpg)
Active Transport
Moves things AGAINST concentration gradient
Requires ENERGY in order to “force” it against the concentration gradient (usually ATP)
Donates phosphate group to a transport protein
Binding site on other side improvesSolute bindsProtein changes shape, solute moves to
other side, binding site becomes less attractive
Solute and phosphate releasedProtein goes back to original shape
![Page 17: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/17.jpg)
![Page 18: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/18.jpg)
![Page 19: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/19.jpg)
Exocytosis & Endocytosis
Exocytosis – cytoplasmic vesicle moves to cell surface & fuses with plasma membrane. Vesicle loses shape, but contents released to surroundings
Endocytosis – cell takes in substances next to its surface Small indentation, balloons inward, pinches off
![Page 20: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/20.jpg)
![Page 21: Membrane Structure & Function Ch. 7. Membrane & Function Lipid Bilayer Minimizes number of hydrophobic groups exposed to water Fatty acid tails don’t.](https://reader036.fdocuments.in/reader036/viewer/2022062305/56649ea05503460f94ba3d25/html5/thumbnails/21.jpg)
Three types:
Receptor MediatedMembrane receptors chemically recognize &
bind substances Bulk Phase
Vesicle forms around small volume of extra-cellular fluid regardless of what’s in it
PhagocytosisActive form of Endocytosis where cell takes
in microorganisms and other debris
** Membrane cycling – maintain surface area of membrane