transport Flashcards
Diffusion
Passive movement of molecules from a region of higher concentration to a region of lower concentration (down a concentration gradient)
Osmosis
Passive movement of water molecules, across a partially permeable membrane, from a region of lower solute concentration to a region of higher solute concentration.
Diffusion rate is faster…
as kinetic energy of molecules increase.
As diffusion occurs, what happens to the net flow?
As diffusion occurs, particles start moving from high to low concentration. This keeps happening until an equilibrium is reached. Particles will still move back and forth, but the net movement of particles will be zero.
What are two factors that increases the rate of diffusion
Rise in temperature
Rise in pressure
What can diffuse directly through the lipid bilayer?
Liquid soluble molecules and very small molecules such as oxygen and carbon dioxide can diffuse directly through the lipid bilayer.
What occurs when a particle diffuses through the lipid bilayer?
Any particles that diffuses through the lipid bilayer directly goes through simple diffusion
When does faciliated diffusion occur?
1) too large
2) polar meaning it has a charge (positively charged/negatively charged) rejected by non- polar molecules
What is an example of facilitated diffusion?
Potassium channels in axon
What occurs during facilitated diffusion?
#1: The channel protein is closed as the neuron is at rest. This means it is not transmitting any electric impulse. #2: As the neuron transmit an electric impulse, the channel protein opens. This will allow potassium ions to move inside the neuron. #3: To prevent an excess of potassium ions moving in, the ball and chain mechanism blocks the channel and the channel protein becomes inactivated. #4: The channel protein closes again and releases the ball and chain. The neuron is ready to transmit a new electric impulse.
Why does water move in osmosis?
Water is polar.
H+ attracted to CL-
O- attracted to NA +
Water can go through a semi-permeable membrane and salt (NACL cannot)
Definition of Active Transport
Movement of substances against a concentration gradient (from a low concentration region of solutes to a higher one,) using energy from the hydrolysis of ATP (metabolism of the cell).
What are channel proteins?
Proteins that allow for facilitated diffusion to occur.
Antiporter
transports in opposite directions simultaneously
Endocytosis
The process in which cells ingest large particles or fluid.
The cell membrane begins to pinch around the substances and forms a vesicle which can carry the substance to any part of the cell
Exocytosis
The process in which substances are released from a cell through a vesicle that transports it to the cell surface and fuses with the plasma membrane
The types of endocytosis
Pinocytosis (cell drinking) - intaking large amounts of liquid
phagocytosis (cell eating) intake of large and solid molecules
What is an example of exocytosis?
Protein transport from golgi body
What happens to a cell that is placed in a hypertonic solution of solutes?
The water inside the cell travels outside and the cell shrivels/shrinks.
Because:
In the hypertonic external solution, water moves by osmosis out of the cell, so the cell shrinks.
What happens to a cell that is placed in a hypotonic solution of solutes?
Water travels inside the cell causing the cell to swell and burst.
Because:
In the hypotonic external solution, the concentration of solutes is greater inside the cell than outside of it, so the cell gains water through osmosis and swells up.
What happens to a cell that is placed in an isotonic solution of solutes?
There will be no net movement of water molecules
How does water move?
Water always moves by osmosis from the hypotonic solution to the hypertonic solution.
What are the three types of active transport?
1) membrane pumps
2) Exocytosis
3) Endocytosis
What is a membrane pump?
Carrier proteins that move substances from low concentration to high concentration
What is an example of active transport with a membrane pump?
Sodium potassium pump
How does the sodium potassium pump work?
#1: 3 sodium ions bind to the carrier protein #2: ATP molecule breaks off a phosphate and binds to carrier protein #3: The phosphate gives the carrier protein energy to change shape. #4: Potassium binds and phosphate breaks off to change back into original shape #5: The phosphate detaches, so the carrier protein goes back to its original shape which lets the potassium ions be released into the cytosol
What are the concentration levels of sodium and potassium inside and outside of the cell?
There is a higher concentration of Na+ outside of the cell.
There is a higher concentration of K+ inside the cell.
What are three differences between facilitated diffusion and active transport?
1) In facilitated diffusion no energy is needed, instead in active transport energy is required.
2) In facilitated diffusion it moves from high concentration of molecules to low concentration of molecules while in active transport it moves from low concentration of molecules to high concentration of molecules.
3) In facilitated diffusion channel proteins are used meanwhile in active transport carrier proteins are used.
What is the difference between carrier protein and channel proteins?
Channel proteins are just proteins which allow for facilitated diffusion occur.
Carrier Protein requires energy –> pump proteins. ONLY active transport
