Biomembranes Flashcards
(52 cards)
What is the primary function of cell membranes?
To act as a selective barrier that regulate the movement of substances in and out of cell
What are the main components of cell membranes?
Phospholipids, proteins, cholesterol and carbohydrate
How do phospholipids contribute to membrane structure?
They form a bilayer where hydrophilic (water-attracting) heads face outwards and hydrophobic (water-repelling) tails face inward
How do ion channels regulate membrane potential?
Ion channels allow specific ions to flow across the membrane, which alters the electrical charge inside the cell and generates action potentials.
What role do proteins play in membrane function?
Proteins serve as channels, receptors, and enzymes that facilitate communication and transport across the membrane.
What is membrane permeability?
Membrane permeability refers to the ability of the membrane to allow substances to pass through; it is influenced by factors like lipid solubility and size.
What is the resting membrane potential?
The resting membrane potential is the electrical charge difference across the cell membrane when a cell is not actively sending signals, typically around -70 mV.
What factors influence the resting membrane potential?
Ion concentration gradients (like Na⁺ and K⁺), membrane permeability to different ions, and the activity of the sodium-potassium pump.
What is the sodium-potassium pump?
An ATP-driven pump that extrudes three sodium ions (Na⁺) from the cell and brings in two potassium ions (K⁺), helping maintain the ion gradients essential for membrane potential.
How do receptor proteins regulate cell signaling?
Receptor proteins bind to specific ligands (like hormones or neurotransmitters) and initiate intracellular signaling pathways that affect cell function.
What is the role of cholesterol in cell membranes?
Cholesterol helps maintain membrane fluidity and stability by preventing the fatty acid chains of phospholipids from packing too closely together.
What is facilitated diffusion?
A passive transport mechanism where molecules cross the membrane via specific transport proteins without the expenditure of energy
What is the function of active transport?
Active transport moves substances against their concentration gradient using energy, typically provided by ATP, ensuring necessary ion concentrations are maintained.
How do changes in membrane fluidity affect function?
Changes in fluidity can alter protein function, ion channel activity, and overall membrane integrity, impacting cell signaling and transport processes
What is a concentration gradient?
A concentration gradient refers to the difference in the concentration of a substance between two areas, which drives the movement of solutes from regions of higher concentration to regions of lower concentration.
What is an electrical gradient?
An electrical gradient is the difference in charge across a membrane, which can influence the movement of charged particles (ions) toward an area with the opposite charge.
How do concentration gradients affect solute transport?
Concentration gradients drive passive transport mechanisms, such as diffusion, allowing solutes to move down their gradient without the expenditure of energy
How do electrical gradients influence ion movement?
Electrical gradients pull positively charged ions (cations) toward negatively charged areas and negatively charged ions (anions) toward positively charged areas, impacting their transport across the membrane.
What is facilitated diffusion?
Facilitated diffusion is a passive transport process where specific molecules move across the membrane via protein channels or carriers, driven by their concentration gradient
What role do ion channels play in transport?
Ion channels are membrane proteins that allow selective passage of specific ions based on concentration and electrical gradients, contributing to the maintenance of membrane potential
What is the Na+/K+ ATPase?
The Na+/K+ ATPase is an active transport pump that moves sodium ions out of the cell and potassium ions into the cell against their concentration gradients, using ATP for energy.
How do gradients contribute to the resting membrane potential?
The resting membrane potential is established by the unequal distribution of ions (primarily Na+ and K+) across the membrane, created by concentration and electrical gradients maintained by pumps like Na+/K+ ATPase
What is osmosis, and how is it affected by concentration gradients?
Osmosis is the passive movement of water across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration, driven by concentration gradients
How do electrical and concentration gradients work together?
Together, electrical and concentration gradients create the electrochemical gradient, which determines the direction and magnitude of ion movement across membranes, influencing cell signaling and function.
