Download Cell Transport Systems

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

List of types of proteins wikipedia, lookup

Membrane potential wikipedia, lookup

Mitosis wikipedia, lookup

Cytokinesis wikipedia, lookup

Extracellular matrix wikipedia, lookup

Amitosis wikipedia, lookup

Organ-on-a-chip wikipedia, lookup

Endomembrane system wikipedia, lookup

Cell nucleus wikipedia, lookup

JADE1 wikipedia, lookup

Cellular differentiation wikipedia, lookup

Cell culture wikipedia, lookup

Cell growth wikipedia, lookup

Cell encapsulation wikipedia, lookup

Cell cycle wikipedia, lookup

Signal transduction wikipedia, lookup

Cytosol wikipedia, lookup

SULF1 wikipedia, lookup

Cell membrane wikipedia, lookup

Cell wall wikipedia, lookup

Transcript
Cell Transport Systems
Diffusion
• Mixing of materials by their own random motion
• Mixing occurs from an area of high to low
concentrations
Osmosis
•
•
•
Basically the diffusion
of H2O through a
membrane
Since H2O molecules
are small – they can
pass through
membranes (even nonpolar part)
Follows the same
principles of regular
diffusion (High to low
concentration)
Osmotic pressure
• When a cell is in fresh water, the concentration of water is
greater on the outside than the inside of a cell. This is called a
Hypotonic solution. When this happens, water can fill the cell
and put pressure on the side of it causing pressure – Osmotic
pressure. If osmotic pressure gets too much it can “burst” a
cell. This is called Plasmolysis.
• Many fresh water organisms have built in “sump pumps” to
remove excess H2O. Other Salt water organisms must pump in
water
• Conversely, in a salt-water environment, cells must pump
water into the cell. This is called a hypertonic solution. The
cell can lose water and "shrivel" this is called crenation.
• Cells in larger organisms are surrounded by solution with
roughly equal concentrations of H2O and solvents. This is
called an isotonic solution.
Osmosis illustrated
Isotonic
Hypertonic
Hypotonic
Selective Transports
• Used for molecules which cannot easily
pass through cell membrane because they
are either…
• Too large to pass between phospholipids
• Are polar and cannot pass through non-polar
region eg. ions
• Two basic types
Facilitated Diffusion
• Works by having channel proteins of different sizes (like
a sieve) or ion channels which allow larger, or charged
molecules to diffuse in/out of cell
Active Transports
•
•
•
•
Lets in/out molecules via membrane proteins which actively pump in/out
molecules.
This requires energy from the cell.
Moves molecules in 1 direction AGAINST THE CONCENTRATION
GRADIENT
Example is the Sodium-Potassium Pump.
Sodium / Potassium Pump (Adv. Bio)
Pumps Potassium into & Sodium
out-of cell
6 step process
1.
2.
3.
4.
5.
6.
3 Na+ (Sodium) Ions bind to a
special receptor protein
Energy (from ATP) is added
to the protein.
Protein changes shape,
releasing Na+ from the cell.
2 K+ (Potassium) ions now
bind to the protein
Phosphate is released, protein
returns to its original shape.
K+ ions are released into the
cell interior
Endocytosis
• Large particles enter cells via endocytosis
• Membrane actively surrounds & engulfs particle or fluid
and forms a vacuole.
• Phagocytosis – Cell eating – involves large particles.
• Pinocytosis – Cell Drinking – involves liquids.
Exocytosis
• Large particles exit the cell via Exocytosis
• Vessicle moves to and merges with the plasma membrane.
• Vessicle ruptures outwards, releasing its contents
Receptor mediated endocytosis
• Receptor mediated endocytosis: ligands bind to specific
receptors on cell surface (coated pits)
• Example: human cells take in cholesterol by this process