3.4 Diffusion Flashcards
Diffusion is the net movement of molecules from a region of…
High concentration to a region of lower concentration
Down a concentration gradient
No additional energy is need for diffusion so it is described as a…
Passive process - group of molecules concentrated together in an area will move about at random - eventually resulting in them being evenly distributed within the area
Diffusion is fastest when there is…
A large surface area
A short distance
A large concentration gradient
Facilitated diffusion is a kind of diffusion in which the proteins in the membrane help…
Molecules to diffuse
Some proteins form water-filled pores that span the membrane these allow…
Small water-soluble molecules and ions (glucose or amino acids) to pass through
These channels are specific (only let one kind of molecule/ion through)
Another kind of facilitated diffusion uses…
Carrier proteins - intrinsic proteins which span the membrane
Carrier proteins, like channel proteins, are specific. When the molecule binds with the protein it…
Changes shape
This causes the molecule to be released on the other side of the membrane
Both kinds of facilitated diffusion require…
No additional energy, both use only the kinetic energy or the molecules themselves - passive
Both move molecules from a region of high to low concentration