CELL TRANSPORT MECHANISMS Flashcards
What are cell membranes made up of? (5)
-phospholipids
-glycoproteins
-glycolipids
-cholesterol
-intrinsic and extrinsic proteins
What is a surface membrane?(1)
Selectively permeable….
What are the roles of the cell membrane (surface)? (4)
-separates cell components from the outside of the cell
-controls what gets in and out of cells
-cell signalling via glycoproteins/glycolipids
-cell to cell communication
What are the roles of the cell membrane (within cells)? (3)
-separates contents of cell organelles from cytoplasm
-surface for metabolic reactions (mitochondria)
-allow transport of RNA and ribosomes in and out of the nucleus (nuclear membranes)
What factors affect fluidity of the cell membrane? (3)
-temperature
-cholesterol
-saturated lipids
How does temperature affect fluidity of a cell membrane? (2)
Low temperature- lipids are closely packed/less fluid.
High temperature- lipids get more kinetic energy and therefore more fluid
How does cholesterol affect the fluidity of a cell membrane? (2)
Cholesterol is attached to the fatty acid chains, so keeps molecules together and stops them moving apart-prevents too much fluidity or solidity.
How does saturated lipids affect the fluidity of a cell membrane? (2)
Lipids with long and saturated tails have a high melting point which decreases fluidity.
The straight unkinked fatty acid chains mean the lipid molecules can pack together more closely
what is the equation for water potential? (1)
Turgor pressure + osmotic potential
What is the value for osmotic potential? (1)
Always negative
What is the value for turgor pressure? (1)
Usually positive
What is the value for water potential? (1)
Usually negative
What is turgor pressure? (1)
The inward pressure of the cell wall on the cytoplasm.
What is hydrostatic pressure? (1)
When the cytoplasm swells and presses against the cell walls.
When is a plant cell considered rigid? (1)
When the osmotic force moving water into the plant cell is balanced by the turgor pressure forcing it out, the plant cell is rigid.
