Transport across cell membranes Flashcards
What are membranes made of?
Phosopholipids and proteins.
What is diffusion?
The movement of substances from a high concentration to a low concentration down a concentration gradient.
What kind of process is diffusion (energy)?
A passive process which requires no energy.
Why is diffusion important to living cells?
It is the way that substances are moved from cell to cell and between cells and their surroundings.
What is: The movement of substances from a high concentration to a low concentration down a concentration gradient?
Diffusion.
What is: OSMOSIS?
The movement of water from a high water concentration to a low water concentration through a selectively permeable membrane.
What happens in an animal cell during osmosis if there is a higher water concentration (hypotonic solution)?
Water enters by osmosis and the cell burts.
What happens in an animal cell during osmosis if there is a lower water concentration (hypertonic solution)?
The cell shrinks and wrinkles. Water is lost by osmosis.
Why does osmosis effect plant cells differently?
Because of the presence of a cell wall.
What happens in an plant cell during osmosis if there is a higher water concentration (hypotonic solution)?
Water enters by osmosis. The vacuole swells and the cell is turgid.
What happens in an plant cell during osmosis if there is a lower water concentration (hypertonic solution)?
Lose water by osmosis. The vacuole shrinks and the membrane pulls away from the cell wall. The cell is plasmolysed.
What is: The movement of water from a high water concentration to a low water concentration through a selectively permeable membrane?
Osmosis
Explain what kind of cell this happens to: Water enters by osmosis and the cell burts.
In an animal cell if there is a higher water concentration (hypotonic solution).
Explain what kind of cell this happens to: The cell shrinks and wrinkles. Water is lost by osmosis.
In an animal cell if there is a lower water concentration (hypertonic solution)
Explain what kind of cell this happens to: Water enters by osmosis. The vacuole swells and the cell is turgid.
In an plant cell if there is a higher water concentration (hypotonic solution)
Explain what kind of cell this happens to: Lose water by osmosis. The vacuole shrinks and the membrane pulls away from the cell wall. The cell is plasmolysed.
In an plant cell if there is a lower water concentration (hypertonic solution)
What is: ACTIVE TRANSPORT
The movement of molecules against a concentration gradient from a region of low concentration to a region of high concentration.
What does active transport need to make it happen?
ATP (energy)
What do proteins do in the membrane?
In the membrane proteins act as carriers and transport the molecules (and ions) across the membrane.
What is an example of active transport?
In nerve cells, sodium is pumped out and potassium is pumped in.
What is: The movement of molecules against a concentration gradient from a region of low concentration to a region of high concentration?
Active Transport
In the membrane what act as carriers and transport the molecules (and ions) across the membrane?
Proteins
What is this an example of: In nerve cells, sodium is pumped out and potassium is pumped in?
Active Transport
