methods of transport Flashcards
What is diffusion?
The movement of molecules from an area of high concentration to an area of lower concentration, down a concentration gradient
What is a concentration gradient?
The difference in the concentration of a substance in two different regions.
Is diffusion a passive or active process?
Passive, as it relys on kinetic energy and a concentration gradient for movement and not energy from the cell
What are the two types of diffusion?
Facilitated diffusion and simple diffusion
What is facilitated diffusion?
The movement of molecules down their concentration gradient, across a membrane with the help of carrier proteins.
Is energy required for facilitated diffusion?
Energy is not required.
What are the two types of proteins present in the membrane that facilitate diffusion?
Channel proteins and carrier proteins.
What do channel proteins do?
They form pores, for example calcium and sodium in the membrane, they are shaped to allow particular molecules to pass through. Many are ‘gated’ meaning they can be opened and closed.
What do carrier proteins do?
These have a specific shape complementary to a specific molecule for example glucose and amino acids, when this molecule binds to the protein, the protein changes shape to allow the molecule to pass across the membrane.
What is active transport?
Its the movement of molecules from a lower concentration to a higher concentration , against a concentration gradient, across a bi membrane. Energy in the form of ATP is required.
What is endocytosis?
The movement into a cell. of bulk material
What is exocytosis?
The movement of bulk material out of a cell
What happens during phagocytosis?
Cells engulf a target particle and the membrane forms around it to produce vesicles called phagosomes. This normally happens when the body is trying to destroy a virus.
What is osmosis?
The diffusion of water molecules across a partially permeable membrane from an area of higher water potential to an area of lower water potential
What does semi-permeable mean?
It refers to something that will allow certain particles to pass through it but not others. Another term for ‘partially permeable’.
