Chapter Five Flashcards
What are Membranes?
Amphipathic lipid molecules that form structures to minimize potential energy. Cells naturally form lipid bilayers. The polar, fatty acid, parts will try to interact with water while the non polar parts will not.
Define Amphipathic
An amphipathic molecule is polar at one end and nonpolar at the other.
True or False: the outside and inside of membranes are symmetrical.
False, the extracellular leaflet is not the same as the cytosolic (inside) leaflet.
What are Intrinsic or Transmembrane Proteins?
Proteins that cross the membrane and are embedded in the lipid bilayer.
What are Extrinsic Proteins and Peripheral Membrane Proteins?
Proteins that are more loosely associated with the membrane, they can be attached to transmembrane proteins or lipids.
Why is Cholesterol important in the cell?
It helps keep membranes fluid and functioning in extreme temperatures, they help regulate fluidity of the membrane.
What is the Fluid Mosaic Model?
Lipids can easily move in two dimensions, back and forth, but moving across the membrane is difficult and a transport protein is needed. This requires energy, and the hydrophilic outside has to be protected from the hydrophobic inside.
What are Antibodies?
Proteins produced by the immune system that recognize specific foreign invaders called antigens.
What is Fluorescence Recovery after Photobleaching (FRAP)?
Utilizes Green Fluorescent Protein fusions to see the movement of the cell membrane.
True or False: Membranes with a lot of saturated fatty acids will remain intact at higher temperatures and become solid at lower temperatures.
True, the more unsaturated fatty acids the more fluid it will stay at lower temperatures but it will not function at higher temperatures.
What is the Plasma Membrane?
The semi-permeable selective barrier, polar or charged atoms are excluded.
What is Diffusion?
The net movement of solutes with the concentration gradient
What direction does water move in a hypertonic solution?
Out of the cell.
What direction does water move in a hypotonic solution?
Into the cell.
Turgid versus Plasmolysed
Plant cells can expand and contract due to solute changes, but they will not explode because of the cell wall. Turgid is when the cell is in a hypertonic solution and the cell is swollen, plasmolysed is when the internal volume shrinks and the membrane pulls away from the cell wall.
