Cells 1.4 Membrane transport Flashcards
What is Diffusion?
Diffusion is a passive movement of particles from a region of high concentration to low concentration.
What types of membrane transport are there?
There are two types of diffusion. simplified and facilitated. There is also active transport and osmosis. There is also exocytosis and endocytosis.
What is the difference between diffusion and active transport?
Diffusion does not require energy. Active Transport goes against the concentration gradient while Diffusion goes down the concentration gradient.
Compare simplified and facilitated diffusion.
Both do not require energy Simplified diffusion does not require protein channels. Facilitated diffusion required protein channels. In both diffusions, substances move down a concentration gradient.
What is active transportation?
This is the movement of substances against the concentration gradient. This means it goes from a region of low concentration to high concentration. Unlike passive transportations, this requires energy. Protein pumps are also needed for active transportation. .
What is osmosis?
Osmosis is the movement of water through a semipermeable membrane, from a region of high water concentration to a region of low water concentration Osmosis does not require energy. It is an example of passive transportation.
How are tissues or organs used in medical procedures?
In order to use tissues or organs in medical procedure, the organs must be bathed in a solution of the same osmolarity as the cytoplasm of the cell in order to prevent osmosis.
When doing an experiment with potato chips in different concentrations of salt we found that the sizes of them change. Work out the osmolarity of the potato’s cytoplasm.
The point where the line crosses the X axis, gives us an estimate of the concentration of the cytoplasm of the potato cells. We can also see that at 0.16mol/dm3 the size of the potato chip should not change.
Why is the membrane so efficient for exo- or endocytosis?
Due to the fluidity of the plasma membrane, the membrane can change its shape, break and re-form during endocytosis or exocytosis. Both membrane transportations require energy.
How does endocytosis work?
Endocytosis works through the change of shape of the membrane. The membrane will sink inwardly, forming a pit which encloses the material coming into the cell. The the membrane seals back on itself as the edges fuse. This vesicle then will break away from the membrane and move into the cytoplasm. The particles have now entered the cell enclosed by a vesicle.
How are vesicles used to transport material?
In both exocytosis and endocytosis, vesicles are used to transport materials that are too large to enter the cell through passive or active transport. In exocytosis, protein produced in the RER is send to the golgi apparatus via vesicles which are then packaged and processed to be send via vesicles to the plasma membrane. The vesicle attaches itself to the membrane and fusion to the membrane releases the material inside the vesicle.
