All Flashcards
What is the effect of increasing the concentration gradient on simple diffusion?
Increases the rate of simple diffusion.
What is the effect of a cell being placed in a hypertonic solution?
Water moves out of the cell, causing it to shrink (plasmolysis in plant cells).
What is the effect of blocking ATP production on active transport?
Active transport ceases because it requires ATP as an energy source.
What is the effect of a mutation that disables a specific receptor protein used in receptor-mediated endocytosis?
The cell will be unable to internalize the specific molecule that binds to that receptor.
What is the effect of inhibiting exocytosis in a pancreatic cell?
The cell will be unable to secrete insulin.
What are the general steps of endocytosis?
- Cell membrane invaginates. 2. Substance is enclosed in the invagination. 3. Membrane pinches off, forming a vesicle inside the cell.
What are the general steps of exocytosis?
- Vesicle containing substance moves to cell membrane. 2. Vesicle membrane fuses with cell membrane. 3. Substance is released outside the cell.
Describe the process of phagocytosis.
- Cell extends pseudopodia around a particle. 2. Pseudopodia fuse, enclosing the particle in a vacuole. 3. Vacuole fuses with a lysosome for digestion.
Outline the process of receptor-mediated endocytosis.
- Specific molecules bind to receptors on the cell surface. 2. Receptors cluster together in coated pits. 3. Coated pit invaginates and forms a coated vesicle. 4. Vesicle is internalized into the cell.
Define passive transport.
Movement of substances across a membrane without energy input, moving down the concentration gradient.
Define active transport.
Movement of substances across a membrane requiring energy (ATP), moving against the concentration gradient.
What is simple diffusion?
Movement of a substance from high to low concentration directly across the membrane, without assistance.
What is facilitated diffusion?
Movement of a substance from high to low concentration with the help of a transport protein.
Define osmosis.
The facilitated diffusion of water across a selectively permeable membrane.
What is endocytosis?
The process by which cells engulf substances by inward folding of the cell membrane, forming a vesicle.
What is exocytosis?
The process by which cells release substances by fusion of vesicles with the cell membrane.
Define phagocytosis.
A type of endocytosis where the cell engulfs large particles or cells ('cellular eating').
Define pinocytosis.
A type of endocytosis where the cell engulfs extracellular fluid with dissolved solutes ('cellular drinking').
What is receptor-mediated endocytosis?
A type of endocytosis where specific molecules bind to receptors on the cell surface, triggering vesicle formation.