KA2: Transport across cell membranes Flashcards
What is the cell membrane composed of?
Proteins and (phospho)lipids
A feature of the cell membrane is that…
It is selectively permeable
What does selectively permeable mean?
Will only let certain molecules enter or exit
What molecules does the cell membrane allow through?
Oxygen, glucose, amino acids and carbon dioxide
What is passive transport?
The movement of molecules down a concentration gradient and does not require energy
What is a concentration gradient
The difference in concentration between 2 solutions. Different concentrations of molecules exist between cells and their environment
What is diffusion?
The movement of molecules down a concentration gradient from a higher concentration to a lower concentration. This does not require energy
What is osmosis?
The movement of water molecules from a higher concentration to a lower water concentration through a selectively permeable membrane
There is no change in a red blood cell if…
The water concentration is the same inside and out of the cell
The red blood cell bursts if…
The concentration of water outside of the cell is higher than the inside
The red blood cell shrinks if…
The water concentration outside the cell is lower than the inside of the cell
When a plant cell is placed in water…
The central vacuole swells up and turns into a turgid state. Since the cell is swelled up, this prevents it from bursting
When a plant cell is placed in a sugar solution…
The cell shrinks as the plant is losing water by osmosis. The cell membrane detatches from the cell wall. The cell becomes plasmolysed
What is active transport?
Where molecules and ions move from a lower concentration to a higher concentration against the concentration gradient requiring energy
What is the meaning of hypertonic?
When a solution has a high sugar/salt concentration, low water
