What is the role of proton motive force in indirect transport?
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It stores energy in the concentration gradient of protons, which can drive processes like bacterial flagellum movement.
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What is the role of proton motive force in indirect transport?
It stores energy in the concentration gradient of protons, which can drive processes like bacterial flagellum movement.
What maintains the sodium concentration gradient necessary for sodium-glucose symport?
The sodium-potassium ATPase, which pumps sodium ions out of the cell against their concentration gradient.
What is group translocation in bacteria?
A transport system where the solute is chemically modified during transport, such as glucose being converted to glucose-6-phosphate.
What are the two conformations of the Na+-K+ ATPase pump?
E1 state (high affinity for sodium ions) and E2 state (high affinity for potassium ions).
What is the function of the H+ pumps found in plant vacuoles and animal lysosomes?
To actively transport H+ from the cytosol to the lumen to regulate pH.
What is required for the synthesis of new receptors in cholesterol uptake?
Phosphatidic acid (PA) is needed for synthesizing new receptors.
What is the role of the Ca2+ ATPase pump in muscle relaxation?
It actively transports Ca2+ back to the sarcoplasmic reticulum.
What is the role of phosphorylation in the Na+-K+ ATPase pump?
Phosphorylation triggers a change in conformation of the pump, allowing it to transport ions.
What is indirect ATP-dependent transport?
Transport that does not directly depend on ATP hydrolysis but relies on other energy sources, such as sodium concentration gradients.
What role do cell-surface transferrin receptors play?
They facilitate the uptake of iron by binding to transferrin.
What is released into the lumen when the pump is in the E2 state?
Calcium ions.
What is light-driven active transport?
A process where light serves as the energy source to transport ions, such as in Halobacterium halobium using bacteriorhodopsin.
What does the E1 state of the Ca2+ ATPase pump have an affinity for?
Calcium ions, opened towards the cytosol.
What is the consequence of class 5 cholesterol uptake abnormalities?
Receptors fail to dissociate from LDL particles in the endosome, leading to degradation instead of recycling.
What is the energy source for direct ATP-dependent transport?
ATP hydrolysis, which produces ADP and inorganic phosphate (Pi).
What is the function of ATPase in the context of active transport?
ATPase catalyzes the hydrolysis of ATP and acts as a transport protein.
What happens to the E1 conformation of the pump during phosphorylation?
It changes to E2 conformation.
What high-energy compound is involved in group translocation?
Phosphoenolpyruvate (PEP).
What types of substrates can the ABC superfamily transport?
Ions, polysaccharides, lipids, amino acids, peptides, and proteins.
How does sodium-glucose symport function?
It actively transports glucose into intestinal cells using the sodium concentration gradient, where two sodium ions drive the transport of one glucose molecule.
What role do carrier proteins play in active transport?
Carrier proteins change their conformation to transport molecules across the membrane.
What are the two types of domains in the ABC superfamily?
Two T domains (integral proteins) and two A domains (peripheral proteins).
How many sodium ions are released into the extracellular fluid at the E2 state?
Three sodium ions.
What happens to glucose during group translocation?
It is phosphorylated to become glucose-6-phosphate after transport.
What is transferrin?
A blood plasma glycoprotein that transports iron.
What triggers the release of calcium ions from the sarcoplasmic reticulum?
An action potential.
What is the main difference between passive and active transport?
Active transport requires energy and moves substances against their concentration gradient, while passive transport does not require energy and moves substances along their concentration gradient.
What is the significance of the sodium concentration gradient maintained by the Na+-K+ ATPase pump?
It stores energy (sodium motive force) needed for other metabolic processes in the cell.
What ions bind to the pump after sodium ions are released?
Two potassium ions.
What happens during the E1 state of the Na+-K+ ATPase pump?
The pump faces the cytosolic side, and three sodium ions bind before ATP is hydrolyzed.
What are the two forms of transferrin?
Transferrin (with iron) and apotransferrin (without iron).
What are the two conformations of the Ca2+ ATPase pump?
E1 and E2 states.
