Lecture 8 Flashcards
(15 cards)
What is the primary difference between simple diffusion and facilitated diffusion across the cell membrane?
Simple diffusion occurs without the help of transport proteins, allowing small nonpolar molecules like O2 and CO2 to pass through the lipid bilayer. Facilitated diffusion requires transport proteins to help move substances across the membrane.
Example sentence: Oxygen (O2) and carbon dioxide (CO2) can diffuse through the lipid bilayer via simple diffusion.
How do transport proteins like channels and transporters differentiate in function?
Channels allow the passage of molecules based on size and charge when they are open, while transporters require specific binding with the molecules they transport, functioning similarly to an enzyme-substrate relationship.
Example sentence: Transporters bind specifically to glucose molecules to transport them across the membrane.
What role does the Na+/K+ ATPase play in primary active transport?
Na+/K+ ATPase uses ATP to pump Na+ out of the cell and K+ into the cell, creating a charge imbalance essential for cellular homeostasis and membrane potential maintenance.
Example sentence: The Na+/K+ ATPase pump is crucial for maintaining the resting membrane potential in nerve cells.
Describe the function of secondary active transport and provide an example.
Secondary active transport uses the gradients established by primary active transport to move other molecules, such as the Na+/Glucose co-transporter which utilizes the Na+ gradient to bring glucose into cells.
Example sentence: The Na+/Glucose co-transporter uses the sodium gradient to transport glucose into intestinal cells.
What is the electrochemical gradient and how does it influence transport across cell membranes?
The electrochemical gradient is the combined effect of the ion concentration gradient and the electrical charge gradient across a membrane, which influences the movement of charged molecules during transport.
Example sentence: The electrochemical gradient drives the movement of ions like potassium (K+) across the cell membrane.
Explain how the Na+/Ca2+ exchanger functions in cardiac cells.
The Na+/Ca2+ exchanger in cardiac cells uses the gradient of Na+ to move Ca2+ in the opposite direction, aiding in muscle relaxation by balancing intracellular Ca2+ levels.
Example sentence: The Na+/Ca2+ exchanger helps regulate calcium levels in cardiac muscle cells during relaxation.
What are the main types of vesicular transport and their respective functions?
Endocytosis (including pinocytosis, phagocytosis, receptor-mediated endocytosis) is for intake of substances, while exocytosis releases substances and aids in membrane recycling.
Example sentence: Endocytosis is important for the uptake of nutrients into cells.
How does receptor-mediated endocytosis ensure specificity in molecule uptake?
In receptor-mediated endocytosis, specific receptors on the cell surface bind to particular molecules, which are then internalized in vesicles.
Example sentence: Receptor-mediated endocytosis allows cells to selectively take up specific nutrients.
Why is the proton pump (H+/K+ ATPase) important in maintaining stomach acidity?
The proton pump (H+/K+ ATPase) actively transports H+ ions into the stomach, maintaining its acidic environment necessary for digestion.
Example sentence: The proton pump is crucial for the production of gastric acid in the stomach.
Distinguish between passive and active transport mechanisms in terms of energy usage.
Passive transport moves substances from high to low concentration without energy, while active transport requires energy, often from ATP, to move substances against their concentration gradients.
Example sentence: Passive transport does not require energy input from the cell.
What is the role of transport proteins in pharmacological applications?
Transport proteins can influence drug absorption, distribution, and excretion, playing critical roles in treatments for diseases such as diabetes and heart failure.
Example sentence: Transport proteins can affect the effectiveness of drug therapies.
How does the Na+/H+ antiporter contribute to kidney function?
The Na+/H+ antiporter in kidneys excretes protons into the urine, thus regulating pH and is influenced by aldosterone to maintain electrolyte and acid-base balance.
Example sentence: The Na+/H+ antiporter helps regulate the acid-base balance in the kidneys.
Why are transport proteins critical for cellular homeostasis?
Transport proteins maintain cellular homeostasis by regulating the movement of nutrients, ions, and waste products in and out of the cell, ensuring a stable internal environment.
Example sentence: Transport proteins help keep the cell’s internal environment stable.
What is the functional significance of K+ channels in excitable cells?
K+ channels help in repolarizing the membrane after an action potential, restoring the cell’s resting state and preparing it for the next signal in excitable cells such as neurons.
Example sentence: Potassium channels are essential for nerve signal transmission.
How do voltage-gated ion channels differ from ligand-gated channels?
Voltage-gated ion channels open or close in response to changes in membrane potential, whereas ligand-gated channels open or close in response to the binding of specific molecules (ligands).
Example sentence: Voltage-gated channels respond to changes in electrical charge, while ligand-gated channels respond to chemical signals.
