Biochem Chapter 7 Flashcards
Lipid Bilayer
double layer with proteins embedded throughout
Why is it called the Fluid Mosaic Model?
Fluid because the proteins are moving around in the bilayer and the bilayer (phospholipids) are flexible. Mosaic because there are a bunch of macromolecules making up a membrane
Why do proteins move slowly in the fluid environment of the membrane
proteins are larger than lipid molecules
Is the membrane symmetrical? Why or why not
The membrane is very asymmetrical. Proteins on one half of the lipid bilayer differ in function from those that make up the other half of the bilayer
What are the three components of the plasma membrane?
Phospholipids, Membrane Proteins, Glycolipids and Glycoproteins
What are the dominant lipids found in the membrane?
Phospholipids
Parts of the phospholipid molecule
Fatty acids/tail/polar region, polar region/head which includes a glycerol, phosphate group, and polar alcohol coline
when do phospholipids form a bilayer? Why?
when added to an aqueous solution. The non-polar, hydrophobic fatty acids aggregate together while the polar, hydrophilic heads associate with water. This arrangement is favoured because they represent the lowest energy state, and therefore are more likely than any other arrangement to occur.
What major factors are fluidity influenced by
Composition and Temperature
Do saturated fats pack tighter or looser?
Tighter because there are no kinks and bends
Do unsaturated fats pack tighter or looser?
Looser because they have double bonds so their kinks and bends take up space.
Membranes remain in a ____ ____ over a variety of temperatures
fluid state
If the temperature drops low enough…
molecules will become densely packed forming a highly viscous gel
The fluidity of a membrane is related to how many lipids are _____
unsaturated. the more unsaturated, the lower its gelling temperature
Sterols like _____ help to _____
cholesterol, stabilize the membrane
At high temperatures, cholesterol
reduces fluidity by restraining the movement
At low temperatures, sterols
increase fluidity by occupying the space between lipid molecules (preventing tight packing)
What is the function of transport of proteins
help move substances across the membrane that cannot move freely through
What acts as enzymes for important chemical reactions such as cellular respiration
enzymatic activity
Signal Transduction
may bind to chemicals such as hormones, which triggers changes on inner surface of the membrane
Cell to Cell Recognition
recognizes markers on other cells
joins two cells together
intercellular joining
If proteins are embedded in the lipid bilayer they are called
integral membrane proteins (IMP)
If proteins are positioned on the surface of a membrane they are called
Peripheral membrane proteins (PMP)
A lipid and a carb are called
glycolipids
A carb and a protein are called
glycoproteins. They face the exterior of the cell and often play a role in cell to cell recognition
