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What is the primary function of the plasma membrane?
To act as a barrier and regulate the movement of substances in and out of the cell.
What does the term 'Fluid Mosaic Model' refer to?
A concept that describes the organization of the plasma membrane as a fluid combination of lipids and proteins.
What are the three key structures of the plasma membrane?
Phospholipids, proteins, and cholesterol.
Define selectively permeable membrane.
A membrane that allows certain molecules to pass while blocking others.
What is the role of integral membrane proteins?
They span the lipid bilayer and are involved in transport and communication.
What is the purpose of glycoproteins in the plasma membrane?
They play a role in cell recognition and signaling.
What is the difference between diffusion and osmosis?
Diffusion is the movement of solutes, while osmosis is the movement of water across a selectively permeable membrane.
What is osmotic pressure?
The pressure required to prevent the flow of water across a semipermeable membrane due to osmotic gradient.
What are the three types of tonicity?
Hypertonic, isotonic, and hypotonic.
Explain hypertonic solutions.
Solutions with a higher concentration of solutes outside the cell causing the cell to shrink.
Define isotonic solutions.
Solutions where the solute concentration is equal inside and outside the cell.
What happens in hypotonic solutions?
More solute inside the cell than outside, causing the cell to swell.
What is the function of the Na+-K+ pump?
To actively transport sodium out of cells and potassium into them against their concentration gradients.
What is facilitated diffusion?
The passive movement of molecules across the plasma membrane via channel or carrier proteins.
What are the two categories of endocytosis?
Phagocytosis and pinocytosis.
What is the major role of exocytosis?
To transport materials out of the cell.
What is a characteristic feature of gap junctions?
They allow communication and the transfer of ions between adjacent cells.
What triggers the opening of ligand-gated channels?
The binding of a specific ligand to the channel protein.
How are desmosomes classified?
As structures that provide adhesion between cells, connecting the cytoskeletons.
What is the purpose of the extracellular matrix?
To provide structural support and signaling for cells.
How do channel proteins assist in facilitated diffusion?
By providing a porous pathway for specific ions or molecules to move down their concentration gradient.
What does active transport require that passive transport does not?
Energy, usually in the form of ATP.
Define pinocytosis.
A form of endocytosis involving the ingestion of liquid into the cell.
What is the significance of phospholipid bilayers?
They form the fundamental structure of the plasma membrane, providing a barrier between the cell's interior and exterior.
Describe the role of integrins in cell-matrix adhesion.
Integrins are transmembrane proteins that facilitate adhesion between cells and the extracellular matrix.
Which process moves substances against their concentration gradient?
Active transport.
What is the role of cholesterol in the plasma membrane?
To maintain fluidity and stability of the membrane at different temperatures.
Explain the concept of channel proteins.
Proteins that create a passageway for specific ions and molecules to pass through the membrane.
What distinguishes primary active transport from secondary active transport?
Primary uses ATP directly, while secondary relies on the electrochemical gradient created by primary transport.
What occurs during phagocytosis?
The cell engulfs large particles or pathogens, forming a phagosome.
What is a cargo adaptor in exocytosis?
Proteins that help to recruit and bind cargo molecules for transport.
Define the role of the cytoskeleton in the cell.
It provides structural support, shape, and the capability for movement.
Describe the action of voltage-gated channels.
They open or close in response to changes in membrane potential.
What is the main difference between smooth and rough endoplasmic reticulum?
Rough ER has ribosomes on its surface, while smooth ER does not.
What is the main function of peroxisomes?
To break down fatty acids and detoxify harmful substances.
What do tight junctions do in epithelial cells?
They prevent leakage of fluids and solutes between adjacent cells.
What is the purpose of vescile-coated clathrin during endocytosis?
To help form vesicles that transport specific molecules into the cell.
What is a common characteristic of all transport proteins?
They facilitate movement of substances across the cell membrane.
What occurs during receptor-mediated endocytosis?
Cells utilize specific receptors to bring in certain substances in a highly selective manner.
List one example of a drug that targets transporters.
Cocaine, which affects the neurotransmitter reuptake transporters.
How do gap junctions enhance cellular communication?
By allowing direct transfer of ions and small molecules between adjacent cells.
Why is maintaining cell shape important?
It is essential for proper cellular function and responses to environmental changes.
What are connexins?
Proteins that form gap junctions and allow communication between cells.
Summarize the role of receptor proteins on the cell surface.
They bind to specific signaling molecules, initiating a cellular response.
