5. Transport Across The Cell Membrane Pt2 Flashcards
Define Active Transport
Movement of substances across the membrane against the concentration gradient. Molecules move from low to high via carrier proteins and require ATP as an energy source.
Carriers:
Ions e.g. sodium and potassium
Bind -> shape change -> release
Define Vesicular Transport
Transport across the membrane in vesicles – this is a form of mass transport. Form of active transport because energy is required to move vesicles into or out of a cell.
Two forms:
1. Endocytosis
2. Exocytosis
Define Endocytosis
Endocytosis – taking vesicles containing liquids or solids into a cell
Define Exocytosis
Exocytosis - when the contents of a vesicle are passed out of a cell
Define Phagocytosis
- Means ‘cell eating’
- Solid particles are taken into the cell (endocytosis) by the cell membrane folding around the solid particle, forming a vacuole.
- The vacuole pinches off from the membrane and is suspended in the cell’s cytoplasm.
Define Pinocytosis
- Means ‘cell drinking’
- Liquid particles are taken into the cell (endocytosis) by the cell membrane folding around the solid particle, forming a vacuole.
- The vacuole pinches off from the membrane and is suspended in the cell’s cytoplasm