Transport Across Membranes Flashcards
(42 cards)
What reaction forms an ester bond in a phospholipid?
Condensation (reaction).
What is lost during ester bond formation in a phospholipid?
Water.
What two molecules form the ester bond in a phospholipid?
Glycerol and fatty acid.
How are phospholipids arranged in a cell membrane?
Bilayer.
Where is water located in relation to the phospholipid bilayer?
Inside and outside the cell.
Which phospholipid tails point away from water?
Hydrophobic (fatty acid) tails.
Which phospholipid heads point to water?
Hydrophilic (phosphate) heads.
Why is the cell membrane described as fluid?
Molecules can move around within the membrane.
Why is the membrane described as a mosaic?
Made of different molecules arranged in a mosaic.
How do small/non-polar molecules move across membranes?
Simple diffusion down concentration gradient.
How do large/polar molecules move across membranes?
Facilitated diffusion via protein carrier/channel.
How does water move across membranes?
Osmosis down water potential gradient.
How does active transport move substances?
Against concentration gradient using ATP.
What is co-transport?
Movement of two substances via carrier protein.
How do small/non-polar molecules cross membranes?
Via phospholipids/bilayer.
How do large/polar molecules cross membranes?
Via proteins.
In which direction does active transport move substances?
From low to high concentration.
Which proteins are involved in active transport?
Carrier proteins.
What energy does active transport require?
ATP.
What process uses Na+ and glucose?
Co-transport.
What does the phospholipid bilayer allow?
Diffusion of non-polar/lipid-soluble substances.
What does the phospholipid bilayer prevent?
Diffusion of polar/charged/lipid-insoluble substances.
What do membrane proteins allow?
Polar substances to cross.
What role do carrier proteins have?
Allow active transport.
