anatomy

1. substances generally move across cellular membrane via transport processes that can be classified as passive or active. They permit some substances to pass more readily than others, this is called selective permeability.

1.) Diffusion - a passive process in which a substance moves from an area of higher to lower concentration.

Osmosis - a passive process that involves the movement of water molecules across a selectively permeable membrane from an area of lower water concentration.

A. facilitated diffusion - passive movement of a substance down its concentration gradient via transmembrane proteins that act as transporters.

b. active transport - an active process in which cell expends energy to move a substance across the membrane against it's concentration gradient through transmembrane proteins that act as transporters.

c. transport vesicles - an active process that involves the movement of substances into or out of a cell in vesicles that bud from the plasma membrane.

movement of substance into a cell in vesicles

a.) passive - moving a substance down its concentration gradient to cross a membrane using only its kinetic energy. to go from a level of high to low , so as to balance out/make even.ex: diffusion , osmosis , facilitated diffusion

b.) Active- moving a substance from an area of low to high. useing cellular energy to drive the substance uphill against its concentration gradient. energy is used in the form of ATP.ex: active transport , transport in vesicles