Diffusion plasma membranes Flashcards
Diffusion is
Net movement of substance down its concentration gradient
greater concentration
to lower concentration
function of plasma membranes
- Physically separates interior of cell from external environment
- Receives information about changes in environment
- Regulates passage of materials in and out of cell
- Communicates with other cells
- Forms compartments to allow separate functions
- Participates in biochemical reactions
functions of Lipid Bilayer
Flexible and self-sealing
Fuses with other membranes
– allows transport of materials within cell
Forms vesicles
function of membrane proteins?
- Transport materials
- Act as receptors for
extracellular
molecules - Recognize other
cells - Structurally link
cells
what is Osmosis
A type of diffusion
H2O molecules pass through a selectively
permeable membrane from high to low concentration
what is Osmotic Pressure
Determined by concentration of solutes
Cells regulate internal osmotic pressure
– to prevent shrinking or bursting
what is Plasmolysis
in hypertonic solution, water moves out
– plasma membrane splits from cell wall
what is Turgor pressure
– in hypotonic solution, water moves in
– cells swell, build pressure against cell walls
Simple diffusion
– molecules or ions move directly through the
membrane
– down their concentration gradien
Facilitated diffusion
specific transport proteins move solutes
across a membrane
– down their concentration gradient
hypotonic
When placed in such a solution the cell swells and bursts
. When placed in such a solution the cell shrivels
hypertonic
A secretory vesicle uses this method to expel its contents outside the cell
exocytosis
A process by which the cell engulfs water (liquid
pinocytosis
A process by which the cell engulfs solid objects such as a pathogen
phagocytosis
