Water Flashcards
Why are water molecules less likely to move away from an area where there are lots of solute molecules?
Water molecules form hydrogen bonds so there are less “free” water molecules moving around.
What is the difference between facilitated diffusion and simple diffusion?
Facilitated diffusion requires proteins to help substances cross the membrane.
Channel proteins (3)
- Water filled pores spanning the membrane.
- specific channel proteins transport specific substances.
- wine channels can open and close depending on signal (e.g. hormones)
Carrier proteins (3)
- ion/molecule binds onto carrier proteins which change shape so that they can pass across the membrane.
- specific channel proteins transport specific substances.
Describe one similarity between channel proteins and carrier proteins.
Specific channel/carrier proteins transport specific substances.
Introduction to endocytosis and exocytosis.
Sometimes very large molecules/particles need to be transported across surface membranes. This is achieved by endo/exocytosis. They both require ATP energy.
What is Exocytosis?
The release of substances, usually proteins or polysaccharides. Cell vesicles fuse with the cell surface membrane, releasing their cell contents from the cell.
What is Endocytosis?
Reverse of Exo. Substances are taken into a cell by the creation of a vesicle. Part of the cell membrane engulfs the solid or liquid material to be transports.
Exocytosis is used for (what kind of transport) into/out of the cell?
BULK TRANSPORT
OUT
Endocytosis is used for (what kind of transport) into/out of the cell?
BULK TRANSPORT
OUT OF
