Cell Membranes Test Review Flashcards
Define Bulk Transport
The inward movement of large particles going into the cell because the plasma (cell) membrane engulfs the particle.
Define exocytosis and endocytosis
Exocytosis is large molecules LEAVING the cell
Endocytosis is large molecules ENTERING the cell.
Explain how ATP releases its energy
When ATPs third phosphate breaks off (the negative charges cause the bonds to weaken and break apart) an abundance of energy is released.
What is required for active transport to occur? In what direction does the particles move?
ATP energy and protein carriers are required for active transport. The particles move OPPOSITE of the concentration gradient.
Describe in detail of what happens during active transport
A particle moves across the membrane through the protein carrier, to cause the protein carrier to change shape and let the particle go through, the third phosphate is required so it can stick to the protein carrier. When all of the pieces are in place, the protein carrier will change shape, allowing the particle to move through.
Describe the structure of a phospholipid
The phospholipid has a special feature, that is the polar phophate head and the 2 non-polar lipid tails.
Explain how phospholipids arrange themselves to create a plasma membrane
The phospholipids “double up” to form the plasma membrane. The non-polar lipid tails are facing each other where there is no water while the polar phosphate heads are facing towards the water on the inside and outside of the cell
Define passive transport
Passive transport is molecules moving along the concentration gradient with no energy used
Define diffusion. In which direction does the particles move?
Diffusion is the movement of particles from an area of high concentration to an area of low concentration. The particles move DOWN the concentration gradient
Compare and contrast diffusion with facilitated diffusion
Compare- moves down the concentration gradient
Contrast-Facilitated diffusion uses carriers
What happens when a cell is in a isotonic solution?
The cell stays the same size, because the amount of solutes inside and outside the cell are the same. Water moves inside and outside the cell at the same rate.
If a cell is in a hypotonic solution, what will happen to the cell and why?
The cell will swell because the amount of solutes inside the cell is greater than the amount of solutes outside the cell, causing water to go into the cell.
If a cell is in a hypertonic solution, what will happen to the cell and why?
The cell will shrivel because the amount of solutes outside the cell is greater than the amount of solutes inside the cell, causing water to leave the cell
Explain what the term selective permeability means. Which types of molceules can move through a phospholipid bi-layer and which types have difficulty? Give a specific example of each
Selective permeability means that only certain non-charged small molecules can move through. Anything that doesn’t fit into both of the categories can’t move without using energy. An example of a particle that can move through is carbon dioxide (CO2). An example of a particle that has difficulty going through is Sodium (S)
What is the function of cholesterol in an animal cell membrane
Cholesterol acts as a buffer to stop animal cells from getting too stiff or too fluid
