Membrane Structure & Function Flashcards
What is selective permeability?
The cell membrane’s ability to filter molecules
What was the process of arriving at the fluid mosaic model?
1935: Davson and Danielli proposed sandwich model, which was wrong because it didn’t take into account the amphipathic nature of the proteins
1972: J Singer and G Nicolson proposed the fluid mosaic model
What is freeze-fracture microscopy?
Refer to presentation (why does freeze-fracturing split the membrane down the middle?)
Membranes with what type of fatty acids are more fluid? Why?
Unsaturated, because kinks in the phospholipid tails allow them to be further apart from each other
What does cholesterol do?
Restrains movement of phospholipids at high temperatures, maintains fluidity of membrane at low temperatures
What polarity corresponds to being hydrophobic?
Polar = hydrophilic Non-polar = hydrophobic
What are the 6 major functions of membrane proteins?
Transport Enzymatic activity Signal transduction Cell-cell recognition Intercellular joining Attachment to cytoskeleton & ECM
What are the roles of carbohydrates in the membrane? What are the 2 most common types of carbohydrates on the membrane?
To aid in cell recognition; glycolipids & glycoproteins
What molecules cross the membrane most easily? Give an example.
Non-polar & small (hydrocarbons)
What are the two types of passive transport proteins? Give two examples of channel proteins.
Channel and carrier proteins
Aquaporins
Ion channels
What happens to plant and animal cells when they are in different tonicity solutions?
Animal: Lysed, normal, shrivelled
Plant: Turgid, flaccid, plasmolyzed
What is osmoregulation and how does Paramecium regulate?
The control of water balance in a cell; its contractile vacuole acts as a pump
How do sodium-potassium channels work?
Watch video
What is osmosis?
The diffusion of water from a region of lower solute concentration to higher solute concentration.
What is tonicity? What are the 3 different tonicities?
The ability of a solution to cause a cell to gain or lose water.
