Cell Membrane Flashcards
Generally, what type of compounds freely diffuse across the cell membrane? What type don’t?
- Hydrophobic compounds (non polar): Easy
- Hydrophillic compounds (polar) : Hard
The cell membrane is ______
fluid
Other than changing the degree of saturation of fatty acids, how else does a cell alter the fluidity of the cell membrane?
by changing the amount of cholesterol present
By weight, how much of the membrane is made up of proteins?
Half
Describe peripheral membrane proteins
Are embedded in one side of the membrane
Describe lipid anchored membrane proteins
anchored to the membrane by a covalently attached lipid
Describe integral proteins
Passes all the way through the membrane
What is special about transmembrane/integral proteins?
- transmit signals from environment
- form channel that allow specific substances to pass
What are types of membrane transport?
1) Active transport
2) Passive transport
What type of molecules can pass freely over the membrane?
Small polar and non-polar molecules (water and oxygen)
What is facilitated diffusion?
- passive transport
- for molecules that can’t freely move accross membrane
- membrane protein facilitate the diffusion (protein channels)
Can channels distinguish shape or size of molecule? Can they distinguish different type?
Yes No (ex different types of hexoses)
What are gated channels?
they stop the passage under certain conditions
Why do active transport require additional energy?
Because it moves molecules against the concentration gradient
What are membrane protein that is responsible for water transport, and what type of membrane protein are they?
- Aquaporins
- Integral
