Membrane Structure & Function Chapter 7. Membrane Structure fluid mosaic model – a mosaic of...
-
Upload
april-hodges -
Category
Documents
-
view
221 -
download
0
Transcript of Membrane Structure & Function Chapter 7. Membrane Structure fluid mosaic model – a mosaic of...
![Page 1: Membrane Structure & Function Chapter 7. Membrane Structure fluid mosaic model – a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.](https://reader036.fdocuments.in/reader036/viewer/2022062304/56649ee65503460f94bf6c8a/html5/thumbnails/1.jpg)
Membrane Structure & Function
Chapter 7
![Page 2: Membrane Structure & Function Chapter 7. Membrane Structure fluid mosaic model – a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.](https://reader036.fdocuments.in/reader036/viewer/2022062304/56649ee65503460f94bf6c8a/html5/thumbnails/2.jpg)
Membrane Structure• fluid mosaic model – a mosaic of protein
molecules bobbing in a fluid bilayer of phospholipids
![Page 3: Membrane Structure & Function Chapter 7. Membrane Structure fluid mosaic model – a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.](https://reader036.fdocuments.in/reader036/viewer/2022062304/56649ee65503460f94bf6c8a/html5/thumbnails/3.jpg)
Phospholipids
• amphipathic – hydrophobic & hydrophilic regions
• arrange themselves so that the hydrophobic tails face away from water
• bilayer is held together by weak hydrophobic interactions
![Page 4: Membrane Structure & Function Chapter 7. Membrane Structure fluid mosaic model – a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.](https://reader036.fdocuments.in/reader036/viewer/2022062304/56649ee65503460f94bf6c8a/html5/thumbnails/4.jpg)
Membrane Fluidity• most of the lipids & some of
the proteins drift laterally• lateral movement of
phospholipids is rapid• lateral movement of
proteins is slow• flip-flopping of
phospholipids is rare• fluidity is enhanced by
unsaturated hydrocarbon tails of phospholipids
• cholesterol molecules reduce fluidity but help prevent solidification at low temperatures by preventing tight packing of phospholipids
![Page 5: Membrane Structure & Function Chapter 7. Membrane Structure fluid mosaic model – a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.](https://reader036.fdocuments.in/reader036/viewer/2022062304/56649ee65503460f94bf6c8a/html5/thumbnails/5.jpg)
Membrane Proteins
• mosaic – collage of different proteins embedded in the fluid matrix of the lipid bilayer
• integral proteins – penetrate the hydrophobic core of the lipid bilayer; many are transmembrane
• peripheral proteins – bound to the surface of the membrane
• proteins determine most of the membrane’s specific functions
![Page 6: Membrane Structure & Function Chapter 7. Membrane Structure fluid mosaic model – a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.](https://reader036.fdocuments.in/reader036/viewer/2022062304/56649ee65503460f94bf6c8a/html5/thumbnails/6.jpg)
Membrane Protein Functions
![Page 7: Membrane Structure & Function Chapter 7. Membrane Structure fluid mosaic model – a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.](https://reader036.fdocuments.in/reader036/viewer/2022062304/56649ee65503460f94bf6c8a/html5/thumbnails/7.jpg)
Glycoproteins & Glycolipids
• carbohydrates attached to membrane proteins & lipids
• function as “name-tags” to help distinguish cells (cell-cell recognition)
• important in sorting cells into tissues & organs during embryonic development
• basis for rejection of foreign cells
![Page 8: Membrane Structure & Function Chapter 7. Membrane Structure fluid mosaic model – a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.](https://reader036.fdocuments.in/reader036/viewer/2022062304/56649ee65503460f94bf6c8a/html5/thumbnails/8.jpg)
Membrane Synthesis
• begins in ER• vesicles fuse with
plasma membrane– the inside layer of the
vesicle becomes the outside layer of the cell
![Page 9: Membrane Structure & Function Chapter 7. Membrane Structure fluid mosaic model – a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids.](https://reader036.fdocuments.in/reader036/viewer/2022062304/56649ee65503460f94bf6c8a/html5/thumbnails/9.jpg)
Form Fits Function• the plasma membrane controls traffic into and
out of the cell• exhibits selective permeability – allows some
substances to cross more easily than other• the fluid mosaic model explains how the
plasma membrane is able to do this