- What are the main components of the cell membrane?
– Phospholipids, proteins, and cholesterol
- What is the arrangement of phospholipids in the cell membrane?
– They form a bilayer with the hydrophilic heads facing outwards and the hydrophobic tails facing inwards
- What is the role of cholesterol in the cell membrane?
– It helps maintain appropriate membrane fluidity at various temperatures
- What are integral proteins and what is their function?
– Integral proteins span the membrane and serve as membrane transporters
- What are peripheral proteins and what is their function?
– Peripheral proteins loosely attach to the outer side of the cell membrane, acting as enzymes to facilitate interaction with the cell’s environment
Cell Membrane Functions
- What is the primary function of the cell membrane?
– To separate and protect the interior of the cell from the outside environment
- How does the cell membrane control the movement of substances in and out of the cell?
– It is selectively permeable, allowing only certain ions and organic molecules to pass through
- What are some cellular processes the cell membrane is involved in?
– Cell adhesion, ion conductivity, cell signaling, and serving as an attachment surface for extracellular structures
- How does the cell membrane maintain the internal composition of the cell?
– It allows the cell to control and maintain its internal composition by regulating the movement of molecules across the membrane
- What is the fluid mosaic model of the cell membrane?
– It views the membrane as a fluid structure with proteins inserted into the lipid bilayer, which can move laterally within the membrane
Passive Transport
- What is the difference between hydrophilic and hydrophobic molecules in terms of the cell membrane?
– Hydrophilic molecules are attracted to water and can dissolve in the extracellular and intracellular environments, while hydrophobic molecules are repelled by water and can pass through the lipid bilayer
- What is simple diffusion and how does it occur?
– Simple diffusion is the spontaneous movement of molecules from a region of high concentration to a region of low concentration, without the assistance of any membrane proteins
- What is facilitated diffusion and how does it differ from simple diffusion?
– Facilitated diffusion is a type of passive transport where molecules cross the membrane quickly due to the presence of specific membrane proteins, and it has a maximum rate of transport
- What is osmosis and how does it occur?
– Osmosis is the movement of water molecules through the cell membrane from a region of higher water concentration to a region of lower water concentration
- What is the difference between hypertonic, hypotonic, and isotonic solutions in terms of osmosis?
– In a hypertonic solution, the cell loses water by osmosis and shrinks. In a hypotonic solution, the cell gains water and swells. In an isotonic solution, there is no net movement of water in or out of the cell
Active Transport
- What is active transport and how does it differ from passive transport?
– Active transport requires energy to move molecules against their concentration gradient, while passive transport does not require energy and moves molecules down their concentration gradient
- What are some examples of active transport processes?
– The sodium-potassium pump that maintains the electrochemical gradient across the membrane, and the transport of glucose against its concentration gradient
- How does the sodium-potassium pump work?
– It uses ATP to pump sodium ions out of the cell and potassium ions into the cell, maintaining the electrochemical gradient
- What is the role of the electrochemical gradient in the cell?
– It provides the energy for active transport processes and is used for ATP synthesis in mitochondria and chloroplasts
- How do membrane proteins facilitate active transport?
– They form channels or carrier proteins that allow specific molecules to cross the membrane against their concentration gradient
Membrane Permeability
- What factors affect the permeability of the cell membrane?
– The composition and structure of the membrane, the size and charge of the molecules, and the presence of membrane proteins
- How do membrane proteins regulate the permeability of the cell membrane?
– They form channels or gates that allow specific molecules to pass through, controlling the movement of substances in and out of the cell
- What is the role of the glycocalyx in the cell membrane?
– The glycocalyx is a carbohydrate-enriched coating that helps protect the plasma membrane and is involved in cell recognition and adhesion
- How does the cytoskeleton interact with the cell membrane?
– The cytoskeleton is attached to the cell membrane and helps maintain its structure and shape.