Transport across the cell membrane Flashcards
Simple Diffusion
It is the diffusion of a solvent through a differentially permeable membrane in order to balance the concentration of another substance.
- it’s a passive process (no use of energy)
- Osmosis (passive process), where water passes across the membrane, it is similar to simple diffusion but in the end it is classified as a facilitated diffusion
Faciliatated Transport
- It’s a process that requires special proteins in the membrane so that it can allow molecules to be transported across the membrane.
- Can be passive or active (depends on nature of mechanism)
- high concentration to the side of the membrane with a lower concentration.
Vesicular Transport
- Active process
- Materials are moved in membrane-bound sacs
Net diffusion
It’s the movement of liquid or gas molecules from places of higher concentration to places of lower concentration, along a concentration gradient.
Diffusion of Oxygen
Diffuses into cell because it’s continually used up in the cell for respiration.
Therefore, concentration outside the cell is higher than that inside of the cell. Net diffusion inside the cell
Diffusion of Carbon Dioxide
Continually produced inside the cell by respiration.
High concentration of CO2 inside the cell, therefore net diffusion outside the cell.
Osmosis
It’s the diffusion of a solvent through a different permeable membrane in order to balance the concentration of another substance.
Due to the fact that water is the most important solvent in the human body, osmosis can be considered to be the diffusion of water across a differentially permeable membrane.
- considered to be diffusion of water.
Protein Channels
Channels that provide a pathway for the hydrophilic particles to travel through.
Large molecules cannot fit through but water and ions can
Carrier-mediated Transport
Only opens one side at a time.
Specific substance binds to the binding site of the protein and then the protein changes shape, opening on the other side.
Important characteristics of Carrier-Mediated Transport
- Will only bind to a particular molecule
- Carriers can become saturated.
- Activity is regulated by substances such as hormones
Vesicular Transport
Is the movement of substances across the cell membrane in vesicles.
- Active process ( energy needed to form vesicles )
Endocytosis
Takes liquid or solids into the cell by vesicular transport.
( The cell membrane folds around a droplet of liquid or a solid particle until the droplet or particle is completely enclosed. The vesicle created then pinches off and is suspended in the cell’s cytoplasm. )
Pinocytosis
Taking liquids into the cell
Phagocytosis
When the vesicles contain solid particles.
Exocytosis
When contents of a vesicle inside the cell are passed to the outside.
( A vesicle that is formed inside the cell migrates to the cell membrane and fuses with the membrane. The contents of the vesicle are then pushed out into the extracellular fluid. )
