Lab 2: Plasma membrane and osmosis Flashcards
plasma membrane is comprised of a ___ with cholesterol and proteins incorporated into it
phospholipid bilayer
plasma membrane is comprised of a phospholipid bilayer with ___ and ___ incorporated into it
cholesterol
proteins
how does plasma membrane limit control passage of materials into and out of cell?
limits size of molecules that can pass through
prevents charged molecules from passing thru hydrophobic interior
phospholipids that make up the bilayer have 2 parts:
1) polar head that has a phosphate group – hydrophilic – outside of membrane
2) non-polar tail w/ 2 fatty acid chains – hydrophobic – inside of membrane
how does phospholipid bilayer work?
keeps large and polar (charged) molecules from crossing the membrane freely
but
allows small non-polar to cross the membrane thru diffusion
how can large and polar molecules cross the membrane?
must use a carrier or pore to cross the membrane
passage of material into and out of cell cell occurs via 2 types of processes: (what are they)
physical
physiological
physiological processes – passage of material into and out of cell
require energy
examples:
active transport, endocytosis, exocytosis
physical processes – passage of material into and out of cell
doesn’t require energy
examples:
simple diffusion, facilitated diffusion, osmosis
substances move down concentration gradients (move from area of high [] to low [] )
osmosis
diffusion of water thru cell membrane
do phospholipids permit water to pass thru them?
no – water can’t diffuse thru phospholipids
how does water pass through phospholipids?
through special channels formed by proteins called aquaporins
water potential (definition)
movement of water from high concentration (of water) to area of low concentration (of water)
solutions with high [] of solute have ___ water potential
low water potential
solutions with low [] of solute have ___ water potential
high water potential
