Cell Membrane
What type of molecule forms the main structural component of the cell membrane?
Phospholipids
What is the diffusion of water across a selectively permeable membrane called?
Osmosis
What is activation energy?
The energy that must be overcome to start a chemical reaction.
A red blood cell is placed in a solution with a much higher solute concentration than the cell. What happens to the cell?
The cell shrinks because water leaves the cell
A molecule is small nonpolar and moves from high concentration outside the cell to low concentration inside the cell without ATP or proteins. What transport mechanism is occurring?
Simple diffusion
What property of phospholipids causes membranes to form bilayers in water?
Amphipathic nature (hydrophilic heads and hydrophobic tails)
If a cell is placed in a hypotonic solution what will happen to the cell?
Water enters the cell causing it to swell and potentially lyse
What is an enzyme?
A biological catalyst that speeds up reactions without being consumed.
A plant cell is placed in distilled water. What happens to the cell and why does it not burst?
The cell becomes turgid because water enters but the cell wall prevents bursting
Glucose enters a cell through a membrane protein but still moves from high concentration to low concentration and does not require ATP. What type of transport is this?
Facilitated diffusion
What membrane component regulates fluidity by preventing phospholipids from packing too tightly?
Cholesterol
What does the term hypertonic mean?
A solution with a higher solute concentration than the cell
What is energy coupling?
A cell couples ATP hydrolysis to an unfavorable reaction in order to make the overall process spontaneous.
A cell lacking functional aquaporins is placed in a hypotonic solution. How will water movement compare to a normal cell?
Water will enter more slowly because aquaporins facilitate rapid water transport
A membrane protein moves sodium ions out of the cell and potassium ions into the cell using ATP. What type of transport is occurring?
Primary active transport (sodium potassium pump)
Which molecule would diffuse across the membrane most easily O2 glucose Na+ or DNA?
O2
Why do animal cells lyse in extremely hypotonic environments?
Water enters the cell rapidly and there is no cell wall to prevent swelling
A reaction with ΔG > 0 according to the equation ΔG = ΔH − TΔS.
What is an endergonic reaction?
A red blood cell is placed in a solution where the solute concentration outside the cell is much higher than inside the cell.
What is the cell shrinks (crenation)?
A membrane protein uses the energy stored in an ion gradient to move glucose into the cell.
What is secondary active transport?
Cholesterol is removed from a mammalian cell membrane at body temperature.
What is membrane fluidity increases and permeability may increase?
How do contractile vacuoles help freshwater protists survive in hypotonic environments?
They pump excess water out of the cell
What is a spontaneous reaction with high activation energy?
A reaction has a negative ΔG but proceeds very slowly without an enzyme.
A plant cell is placed in a solution with lower solute concentration than the cytoplasm.
What is the cell becomes turgid?
A mutation prevents a sodium-potassium pump from hydrolyzing ATP.
What is the ion gradient across the membrane will eventually collapse?