The cell membrane controls what goes in and out by
having protein channels that act like funnels in some cases and pumps in other cases
. Passive transport does not require energy molecules and happens when a funnel opens in the membrane, letting molecules flow through.
What determines the direction of diffusion?
The difference in the concentration of a substance between two areas is called the
concentration gradient
. The bigger the difference, the steeper the concentration gradient and the faster the molecules of a substance will diffuse. The direction of diffusion is said to be ‘down' or ‘with' the concentration gradient.
Can a membrane control the direction of diffusion?
This process of diffusion through a membrane protein is called facilitated diffusion, and it can
occur in either direction
, into or out of a cell, depending on where the concentration of molecules is higher.
Does the cell membrane regulate diffusion?
Cell membranes serve as barriers and gatekeepers. … Small polar molecules, such as water and ethanol, can also pass through membranes, but they do so more slowly. On the other hand,
cell membranes restrict diffusion of highly charged molecules
, such as ions, and large molecules, such as sugars and amino acids.
What does the membrane do in diffusion?
Diffusion through a permeable membrane
moves a substance from an area of high concentration (extracellular fluid, in this case)
down its concentration gradient (into the cytoplasm). The passive forms of transport, diffusion and osmosis, move materials of small molecular weight across membranes.
What is the major difference between facilitated diffusion and passive diffusion?
| Simple Diffusion Facilitated Diffusion | Example of simple diffusion: passive transport of small nonpolar molecules across the plasma membrane Example of facilitated diffusion: passive transport of glucose and ions into and out of the cell |
|---|
What does a membrane control?
The cell membrane, also called the plasma membrane, is found in all cells and separates the interior of the cell from the outside environment. … The cell membrane
regulates the transport of materials entering and exiting the cell
.
What are the 3 types of diffusion?
- (i) Simple diffusion is when ions or molecules diffuse from an area of high concentration to an area of low concentration.
- (ii) In osmosis, the particles moving are water molecules.
What Does facilitated diffusion use to move things across the cell membrane?
In facilitated diffusion, substances move into or out of cells down their
concentration gradient through protein channels in
the cell membrane. Simple diffusion and facilitated diffusion are similar in that both involve movement down the concentration gradient.
What requires a membrane bound carrier for transport?
Lipid-insoluble solutes are transported across the membrane by a carrier protein.
Cellular energy
is required for the transport. A solute pump is required. Lipid-insoluble solutes are transported across the membrane by a carrier protein.
Why does diffusion not require a semipermeable membrane?
Osmosis requires a semipermeable membrane. The concentration of the diffusion substance equalizes to fill the available space. The concentration of the
solvent does not become equal on both sides of the membrane
. Hydrostatic pressure and turgor pressure do not normally apply to diffusion.
What affects diffusion rate?
The greater the difference in concentration
, the quicker the rate of diffusion. The higher the temperature, the more kinetic energy the particles will have, so they will move and mix more quickly. The greater the surface area, the faster the rate of diffusion.
Why is simple diffusion across a plasma membrane called passive transport because it?
Facilitated diffusion is sometimes called passive transport because
it requires no external source of energy
.
Is facilitated diffusion active or passive?
Facilitated diffusion is a type of
passive transport
. Even though facilitated diffusion involves transport proteins, it is still passive transport because the solute is moving down the concentration gradient.
What are the similarities and differences between diffusion and facilitated diffusion?
In simple diffusion, the molecules can pass only in the direction of concentration gradient. In
facilitated diffusion, the molecules can pass both in direction and opposite of the concentration gradient
. Simple diffusion permits the passage of only small and nonpolar molecules across the plasma membrane.
Is simple diffusion active or passive?
| Transport Molecules moved Uses energy? | Simple diffusion Small, nonpolar No | Facilitated diffusion Polar molecules, larger ions No | Primary active transport Molecules moving against their gradient coupled to the hydrolysis of ATP Yes | Secondary active transport Molecule going with + molecule going against gradient Yes |
|---|
