Structure and Function of the Plasma Membrane Flashcards
What does the fluid-mosaic model describe?
The plasma membrane as a dynamic and flexible structure where lipids and proteins can move laterally within the layer.
How does fluidity of the membrane get influenced?
By the types of fatty acids present in the phospholipids.
What role do unsaturated fatty acids play in membrane fluidity?
They create kinks in the tails, preventing tight packing and enhancing fluidity.
What are integral proteins?
Proteins that extend across the membrane and can form channels or act as transporters.
What are peripheral proteins?
Proteins attached to the membrane’s surface, often linked to integral proteins or lipid layers.
What is the function of carrier proteins?
They undergo a conformational change to move specific substances across the membrane.
What is selective permeability?
The plasma membrane’s ability to regulate what enters and exits the cell.
Which molecules can easily diffuse through the lipid bilayer?
Small, nonpolar molecules like oxygen and carbon dioxide.
What are aquaporins?
Specialized channel proteins that facilitate rapid water transport across the membrane.
What is active transport?
The movement of substances against their concentration gradient, requiring ATP.
What does the sodium-potassium pump do?
Transports three sodium ions out of the cell and two potassium ions into the cell using one ATP molecule.
What is endocytosis?
The process by which cells take in substances through vesicle formation.
What is exocytosis?
The process by which cells expel materials via vesicle fusion with the plasma membrane.
What is osmosis?
The diffusion of water across a selectively permeable membrane.
What happens to cells in isotonic solutions?
Cells maintain their shape.
What occurs in hypotonic solutions?
Cells swell and may burst (lysis).
What occurs in hypertonic solutions?
Cells shrink (crenation).
What is the extracellular matrix (ECM)?
A network of proteins and carbohydrates outside the cell, providing structural and biochemical support.
What are adhesion junctions?
Junctions that connect adjacent cells, providing mechanical strength.
What are tight junctions?
Junctions that create a barrier preventing the passage of materials between cells.
What are gap junctions?
Junctions that allow direct communication between adjacent cells through small channels.
What is the phospholipid bilayer?
A double layer of phospholipids that forms the core structure of the plasma membrane.
Define hydrophilic.
Water-attracting molecules (polar).
Define hydrophobic.
Water-repelling molecules (nonpolar).
What are glycolipids?
Lipids with carbohydrate chains attached, playing a role in cell recognition.
What are glycoproteins?
Proteins with carbohydrate chains, involved in signaling and recognition.
What are channel proteins?
Proteins that form pores in the membrane, allowing specific molecules to pass through.
What are cell recognition proteins?
Glycoproteins that help identify cells to the immune system.
What are receptor proteins?
Proteins that bind specific molecules and trigger a cellular response.
What are enzymatic proteins?
Proteins that catalyze biochemical reactions in the cell.
What is facilitated transport?
The process of moving molecules across the membrane through specific transport proteins without energy use.
What is diffusion?
The movement of molecules from an area of higher concentration to an area of lower concentration.
What is an isotonic solution?
A solution with equal solute concentration inside and outside the cell.
What is a hypotonic solution?
A solution with a lower solute concentration compared to the inside of the cell.
What is a hypertonic solution?
A solution with a higher solute concentration compared to the inside of the cell.
What are plasmodesmata?
Channels in plant cell walls that connect adjacent cells, allowing material exchange.
