University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

329

Pages:

4
Author:

Mariam A. A.

Fluid mosaic • - • Consists of phospholipid molecules that will arrange themselves. Because they are amphipathic their hydrophobic fatty acid feet sychins will associate with one another, and their hydrophilic phosphate head group will sit one the outise close to the water. These will spontaneously form this lipid bilayer. Within that lipid bilayer you will find proteins. These are called membrane proteins, because are sitting within the membrane. The fluid mosaic model shows that these proteins can move around within those phospholipids. They can move laterally and can flow around, but they can’t move vertically u or down. • - - They took out a human cell with a specific protein on it labelled in red and they took out a specific mouse cell with protein on it labelled in green. They fused those two cells together. They found that the after the ae fused about 40 min later that all of the human proteins and the mouse proteins have moved into their respective sides of the cell. It was clear that this membrane allowed the movement of those membrane proteins within the entire membrane. Cell membranes • Lipids in cell membranes - Phospholipids: has a phosphate head group and then we have a hydrophobic fatty acid tail. - Cholesterol: will sit within the membrane, we have 30% of cholesterol in our membranes - Glycolipids: Similar to phospholipids, but instead of having a phosphate group they have a sugar group. Glyco- relates to sugar in some way. - Microdomains: these lipids can form microdomains. Certain proteins can be targest to specific domains and those domains will be in a specific part of the cell. • Membrane proteins - Adhesion proteins: Desmosomes they anchor cells together and hemi-desmosomes, tissues where they anchor cells to their basement membranes. These are sticky adhesion proteins they will sit within the membrane and will attach to something outside the cell. Communication proteins: sit in the membrane and form pores between two cells and allow for communication between the two cells. - Receptor proteins: The biggest group, we have a legened that will bind to receptor. • Example of a G protein coupled receptor, this legend can be indougenous but it could be a drug. It will come along and will bind the G protein receptor and cause intercellular cascade within the cell. It will cause the signal to be transduced and what the singal becomes can be be different between many receptors, but the factors that we are taking and outside singal and conveying that to an intercellular side of the cell. - Recognition proteins - Transport proteins: transport a substance from one side of the membrane to the other. E.g. glucose to inside the cell so that we can take energy. ✓ Passive ✓ Active - Phospholipids • • Phosphate group: Amphipathic: both water loving and water hating. They will spontaneously in a bilipid layer when but in an aqueous environment. Phospholipids come in many different types. This is shown by the diagram below. Phospholipid membranes – asymmetry • - The phospholipids that are on the extracellular side of the membrane are different to those on the cyto side. There are enzymes called flipiases that will find phospolipds that are on the wrong side and flip it to the correct side.