Diffusion Flashcards
What type of transport is diffusion?
passive
Why are all particles constantly in motion?
they have kinetic energy
What can we say about the motion of particles?
random, bounce off one another and the other objects
What is the definition of diffusion?
net movement of molecules or ions from a region where they are more highly concentrated to a region where their concentration is lower until evenly distributed
Which molecules can pass straight across a cell surface membrane?
small, non polar molecules e.g. oxygen and carbon dioxide
What is a polar molecule?
one with an uneven distribution of charge
Why do charged ions and polar molecules NOT diffuse easiily through the membrane?
due to the hydrophobic fatty acid tails of the phospholipids
What membrane structures does facilitated diffusion involve?
carrier and channel proteins
Why is it important we talk about the net movement of particles?
particles continue to move backwards and forward when there is equilibrium, we refer to the overall (net) movement
What is a protein channel?
a water filled hydrophilic channel that allows ions to pass through
What do we mean when we say channel and carrier proteins are selective?
they only allow specific ions/molecules through
How does a carrier protein allow molecules to pass across the membrane in facilitated diffusion?
the molecule binds to the protein, causes a change in shape of the protein, molecule released on the other side of the protein
State 3 factors that affect the rate of diffusion
concentration gradient, temperature, surface area
