Transport Across Membrane Ch 4 Flashcards
Why is the membrane known as the “Fluid- dyanmic model”
Because the membrane in dynamic and water like, and is made up of different molecules such as protein, phospholipids, glycoproteins and gylcolipids and cholestral
Why is phosopholipid in the membrane
It produces a phospholipid bilayer, due to it hydrophobic fatty acids but hypraphilic phosphate
Why is Cholestral in the membrane
Provides strength to the membrane and allows the membrane to break and fuse.
Why is Proteins in the membrane
to help transport molecules through the membrane, (carrier, pump and channel )
Why is glycoproteins, glycolipids in the membrane
Act as antigens, cell to cell adhesion, and binding sites ( for hormones)
Diffusion
The movement of molecules down a concentration gradient until there is a balanced distribution
When is facilitated diffusion used
When molecule is too large, solube in water or polar
Osmosis
The net movement of water from high concentration to a region of low concentration through a selectively permeable membrane
Water moves for …. water potential to …. water potential
negative water potential to more negative water potential
Active Transport
The movement of molecules into and out of a cell up a concentration gradient using ATP and a carrier protein
Describe Active Transport
Molecule binds to the receptor site of the carrier protein. ATP binds to the protein and ATP is hydrolysed to ATD. The protein changes shape and releases the molecule on the other side. When phosphate is released the protein changes shape again
Co-tranport
When two molecules are transported through a protein
Cells lining ileum of mammals absorb the monosaccharide glucose by co-transport. Explain how
Sodium ions are actively transported from epithelial cell to blood capillary
This forms a concentration gradient for sodium to enter the cells from the lumen through the co-transport protein
Glucose enters by facilitated diffusion with sodium ion.
All the ways substances can move through the cell-surface membrane
Diffusion, Facilitated diffusion, osmosis, Endocytosis ( Engulfing by cell surface membrane to form
vesicle) and Exocytosis (Fusion of vesicle with cell surface membrane in golgi apparatus)
