KA 2: Transport Across The Membrane Flashcards
What is a phospholipid?
A component of the cell membrane.
What is a protein in the context of the cell membrane?
A component of the cell membrane that requires energy to move molecules and ions against the concentration gradient.
What is diffusion?
The movement of molecules down a concentration gradient from a higher concentration to a lower concentration.
What is osmosis?
The movement of water molecules from a region of high water concentration to a region of lower water concentration through a selectively permeable membrane.
What is active transport?
Energy is needed for membrane proteins to move molecules and ions against a concentration gradient from a low concentration to a high concentration.
What is passive transport?
The movement of molecules down a concentration gradient which does not require energy.
What does selectively permeable mean?
A term used to describe a feature of the cell membrane that only allows small molecules to pass through.
How are molecules / ions moved against the concentration gradient?
They are moved by proteins against the concentration gradient.
What is a concentration gradient?
The difference in concentration between two regions/areas e.g. inside a cell (intra-cellular) and outside a cell (extra-cellular).
What happens to an animal cell when placed in a strong salt solution?
It shrinks.
What does plasmolysed mean?
A term used to describe the appearance of a plant cell when placed in a strong salt solution.
What is the function of the cell wall in plant cells?
It prevents plant cells from bursting when placed in water.
What does turgid mean?
A term used to describe the appearance of a plant cell when placed in pure water.
What happens to animal cells when placed in pure water?
They swell and burst.
What is the composition of the cell membrane?
It is made of phospholipids and proteins and controls which molecules / substances can enter or leave a cell.
