Bio Chapter 7 Flashcards
How does Lipid bilayer forms in water
Spontaneously
Hugh Dawson& James Danielly they agreed that the phospholipid bilayer lies between 2 layers of globular proteins
Sandwich Model
What was the problem of sandwich model?
The placement of membrane proteins, which have hydrophilic and hydrophobic regions
What J.Singer& G. Nicolson proposed about the membrane
Membrane is a fluid structure with a mosaic of proteins embedded and attached within the bilayer, with only the hydrophilic regions exposed to water
what is most abundant ins mosaic model
phospholipids
two types of proteins in mosaic model
integral- inside the layer
peripheral - on top of layer
What are embedded proteins in the membrane
amphipathic
Membranes are what?
fluid
unsaturated
mosaics
glycoprotein
sugar covalently bonded to protein
differentiate different species
glycolipid
sugar covalently bonded to lipid
peripheral proteins
not embedded but loosely bound to membrane surface
bottom and top of the membrane
integral proteins
transmembrane proteins
amphipathic- penetrate the hydrophobic core if the lipid bilayer
functions of integral proteins
transport coded from the DNA, structure is specific, very specific things can come out and come in
enzyme activity
cell-cell recognitions
Why is membrane selectively permeable
conservative
homeostasis
What molecules can go through the membrane?
Not much regulation
small, non-polar molecules
What molecules can not?
Ions and polar molecules
What about water
Can cross over the membrane but slow
- aquaporins
Passive Transport
No energy required
AKA diffusion
Naturally move through the membrane
spontaneously move from high concentrations to low concentration
Facilitated diffusion
uses transport proteins to move things through the membrane
still move from area of high to low concentration