Diffusion Flashcards
What are the key facts of transport of movement and transport of particles?
- Particles are constantly in motion, due to possessed kinetic energy.
- Motion is random.
- Particles are constantly colliding with each other.
What is the definition of diffusion?
The net movement of molecules or ions from a region where they are more highly concentrated to one where their concentration is lower, until evenly distributed.
How is the movement of molecules that are not able to easily pass through membranes made easier?
The movement is facilitated by transmembrane channels and carriers that span the membrane.
What is the name of the process that makes diffusion easier for molecules that are not able to easily diffuse?
Facilitated diffusion. It is a passive process relying on the kinetic energy of diffusing molecules. There is no external input of ATP from respiration, and can only occur at certain points on the membrane where there are special protein channels, and carrier proteins.
What are protein channels?
Water-filled hydrophilic channels that allow specific water soluble ions to pass through.
What is significant about the protein channels being selective?
They only open in the presence of a specific ion, meaning there is control over the entry and exit of molecules.
What causes the channels to change shape to allow passage of molecules?
The ions bind with he protein causing it to change shape, which closes to one side of the membrane and opens it to the other side.
How do carrier proteins allow passage of molecules?
When a molecule such as glucose that is specific to the protein is present, it binds with the protein causing it to change shape to release the molecule inside the cell.
Where does the energy come from to operate carrier proteins?
No external energy is needed. The kinetic energy of the molecules themselves allows them to move from an area of high concentration to low.
