Cell membranes and transport Flashcards
What is the basic structure of the cell membrane?
The cell membrane is primarily composed of :-
- phospholipid bilayer
- embedded proteins
- cholesterol
- glycolipids
- glycoproteins.
What is the role of the phospholipid bilayer in the cell membrane?
The phospholipid bilayer forms a semi-permeable barrier that separates the intracellular and extracellular environments, allowing selective passage of substances.
What are integral proteins in the cell membrane?
Integral proteins span the membrane and are involved in transport and signaling.
What are peripheral proteins in the cell membrane?
Peripheral proteins are attached to the membrane surface and are involved in cell signaling and maintaining the cell’s shape.
What role does cholesterol play in the cell membrane?
Cholesterol helps to stabilize the membrane’s fluidity, making it less permeable to very small water-soluble molecules that might otherwise pass freely through.
What are the functions of glycolipids and glycoproteins in the cell membrane?
Involved in cell recognition, communication, and adhesion processes.
What is passive transport?
Passive transport is the movement of substances across the cell membrane without the use of energy, including :-
- diffusion
- facilitated diffusion
- osmosis.
What is diffusion?
Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration until equilibrium is reached.
What is facilitated diffusion?
Facilitated diffusion is the process of spontaneous passive transport of molecules across a membrane via specific transmembrane integral proteins.
What is osmosis?
Osmosis is the diffusion of water molecules through a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
What is active transport?
Active transport is the movement of substances against their concentration gradient, requiring energy in the form of ATP.
What is the sodium-potassium pump?
The sodium-potassium pump is a type of active transport that moves sodium ions out of the cell and potassium ions into the cell, essential for maintaining cellular functions.
What is endocytosis?
Endocytosis is the process by which cells ingest external materials by engulfing them in a vesicle formed from the plasma membrane.
What is exocytosis?
Exocytosis is the process by which cells expel materials in vesicles that fuse with the plasma membrane, releasing their contents outside the cell.
What are the types of endocytosis?
- phagocytosis (cell eating)
- pinocytosis (cell drinking)
- receptor-mediated endocytosis (specific molecules).
