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Transport
Solutions
Solutions continued...
Active Transport
Miscellaneous
100
What is passive transport?
movement across the cell membrane that does not require energy from the cell
100
What is an isotonic solution?
-fluid OUTSIDE cell has SAME free water molecule concentration as cytoplasm INSIDE cell -water diffuses INTO AND OUT OF the cell at EQUAL RATES -cell stays the same size
100
What is turgor pressure?
when a plant cell is placed in a hypOtonic solution... --> the cell wall becomes rigid & pushes inward on the cell --> contains cell, prevents cytolysis(cell bursting) *********RESISTS OSMOTIC PRESSURE*********
100
a) What is active transport? b) Does it require energy? c) If yes, from where is this energy supplied? If no, explain why it does not require energy.
a) the transport of a substance across the cell membrane AGAINST its concentration gradient b) YES! c) from ATP (in animal cells)
100
What is a concentration gradient?
a difference in the concentration of a substance across a space
200
What does the term "equilibrium" mean?
a condition in which the concentration of a substance is equal throughout a given space
200
What is a hypotonic solution?
-fluid OUTSIDE cell has HIGHER free water molecule concentration than INSIDE cell -water diffuses INTO the cell -cell swells
200
What is osmotic pressure?
the measure/pressure of how much water is entering a cell through osmosis
200
What is the sodium-potassium pump?
-"a complete cycle" -transports 3 sodium ions (Na+) out of a cell and transports 2 potassium ions (K+) into the cell.
200
Explain the difference between the "solute" and the "solvent" in a solution.
solute -- the dissolved substance (in a solution) solvent -- the liquid in which something(the solute) is dissolved
300
What is diffusion?
-the movement of a substance from an area of HIGH concentration to an area of LOWER concentration -caused by the random motion of the particles of a substance
300
What is a hypertonic solution?
-fluid OUTSIDE cell has LOWER free water molecule concentration than INSIDE cell -water diffuses OUT OF the cell -cell shrinks
300
What is plasmolysis?
when a cell LOSES WATER (in a hypertonic solution) --> cell shrinks/shrivels
300
Explain the difference between endocytosis and exocytosis.
endocytosis -- the movement of a substance into a cell by a vesicle exocytosis -- the movement of a substance by a vesicle to the outside of a cell
300
a) What is an ion channel? b) What is a carrier protein?
a) a doughnut-shaped transport protein, with a polar pore through which ions can pass (through the cell membrane) b) transport protein that can BIND to a specific substance on one side of the cell membrane, CARRY the substance across the cell membrane, and RELEASE it on the other side.
400
What is osmosis?
the diffusion of WATER through a selectively permeable membrane
400
a) What can occur when cells are placed in an extremely hypotonic solution (non-scientific explanation)? b) What is this called (scientific term)? c) How do cell walls prevent help prevent this?
a) cells swell and are in danger of bursting b) cytolysis c) plant cells & fungi cells have rigid cell walls that keep the cells from expanding too much
400
What is cytolysis?
when a cell bursts (in a hypotonic solution) cytolysis = "cell" + "breaking" cyto + lysis
400
a) What is the function of a receptor protein? b) Give an example of when these receptor proteins are used. c) Where are most receptor proteins found?
a) to bind to a specific signal molecule, enabling the cell to respond to the signal molecule b) when human is exercising. receptor proteins and signal molecules work together to send signals for when muscles should contract and relax. c) most receptor proteins are embedded in the phospholipid bilayer of the cell membrane with the part of the protein in which the signal molecule fits facing outside of the cell.
400
Describe the BASIC steps in facilitated diffusion.
1. a molecule outside cell binds to a carrier protein on the cell membrane 2. the carrier protein transports the molecule ACROSS the cell membrane 3. the molecule is released from the carrier protein INSIDE THE CELL, carrier protein returns to its original shape.
500
What is facilitated diffusion?
-type of passive transport -moves substances DOWN their concentration gradient WITHOUT using any of the cell's energy
500
What are contractile vacuoles?
-organelles -in some unicellular eukaryotes -collect excess water inside the cell & force the water out of the cell
500
The types of solutions (hypo-, hyper-, iso-) are used to describe the cell's environment. True or False
FALSE! these adjectives for solutions are (most often; unless said otherwise) used to described the concentration of the SOLUTE in the environment the CELL IS IN **NOT THE CELL'S ENVIRONMENT**
500
a) What is a second messenger? b) What are some way in which second messengers can change the functioning of a cell?
a) second messenger acts like a signal molecule in the cytoplasm (when activated). It amplifies the signal of the first messenger signal molecule b) can activate enzymes (which in turn triggers series of biochemical reaction within the cell), can change the permeability of the cell (by opening ion channels in the cell membrane)
500
Describe the steps in facilitated diffusion IN DETAIL.
1. carrier protein changes shape when binding to a specific molecule on one side of the cell membrane 2. carrier protein exposes molecule to other side of the cell membrane (due to shape change) 3. molecule is transported across the cell membrane BY the carrier protein 4. carrier protein shields molecule from the interior of the phospholipid bilayer 5. molecule is released from carrier protein, carrier protein returns to original shape