1.2.4 Substance transportation Flashcards
Define diffusion.
Diffusion is the net movement from an area of high concentration to an area of low concentration.
What type of molecules easily diffuse?
Small molecules like oxygen can diffuse rapidly across the cell membrane
What is facilitated diffusion?
Molecules diffuse through water-filled pores in the channel proteins. There are different channel proteins for different molecules.
What type of molecules use facilitated diffusion?
Hydrophilic molecules and ions larger than carbon dioxide can’t diffuse through the bilayer, so they use facilitated diffusion.
What is osmosis?
Osmosis is the net movement of water molecules from a solution with lower concentration of solute to a solution with a higher concentration of solute, through a partially permeable membrane
When is active transport used?
Used when a substance needs to move from an area of low concentration to high
What is required for active transport to occur?
ATP energy is required. It changes the shape of the carrier protein.
What is exocytosis?
Exocytosis is the release of substances from the cell as vesicles fuse with the cell membrane
What is an example of exocytosis?
Insulin being released into the blood
What is endocytosis?
Reverse process of exocytosis, part of the cell membrane engulfs the material
What is an example of endocytosis?
White blood cells ingest bacteria this way
What is exocytosis and endocytosis used for?
It is used for the transport of large molecules
