1.4 Membrane transport Flashcards
Key properties of cell membranes
Semi-permeable
Selective
Osmolarity
Solute concentration
Hypertonic
High solute concentration
Gain water (THE SOLUTION)
Hypotonic
Low solute concentration
Loses water (solution LOSES water into the cell)
Isotonic
Same solute concentration
NO NET FLOW
Active Transport
Uses ATP
The fluidity of plasma membrane allows it to…
break and reform aroujd certain materials
Exocytosis
Materials released FROM a cell via vesicles
Endocytosis
Materials internalized within a vesicle
Intercellular vesicles….
move materials between cell organelles
Osmosis
The net movement of water molecules across a semi-permeable membrane
Simple diffusion
Small. Non polar
Examples of small or nonpolar molecules
H20
Glycerol
Examples of large polar molecules
Glucose
Sucrose
Potassium
Sodium
Facilitated diffusion helps
Large, Polar, (ions and macromolecules)
Vesicle transport
ER to Golgi to Membrane
Step 1 of vesicle transport
A polypeptide is destined to be secreted
Signal recognition polypeptides signal ribosome to rough ER
Step 2 of vesicle transport
Ribosome synthesizes polypetide in the lumen of rough ER
Step 3 of vesicle transport
Polypetide is transferred to golgi via vesicles budding from rough ER
Step 4 of vesicle transport
Polypeptide travles from cis to trans face of golgi via vesicles
May be modified
Step 5 of membrane transport. FINAL
Polypetide is finally transferee to plasma membrane via vesicle where it’s secreted
Endocytosis is also
PHAGOCYTOSIS
Endocytocis does what
Engulfs material into an envelope. does not directly pass membrane
Exocytosis does what
Releases large substances via vesicles
Does not travel across the plasma membrane
