general Flashcards
What is the role of the electron transport chain in bioenergetics?
The electron transport chain generates a proton gradient across the inner mitochondrial membrane, driving ATP synthesis through oxidative phosphorylation.
What are uncouplers in bioenergetics, and what do they do?
Uncouplers, like DNP, disrupt the proton gradient, decoupling ATP synthesis from electron transport, leading to energy release as heat.
What is the difference between COPI and COPII vesicle coats?
COPI mediates retrograde transport (Golgi to ER), while COPII mediates anterograde transport (ER to Golgi).
What role does clathrin play in vesicle transport?
Clathrin facilitates the formation of vesicles during endocytosis and transport between the trans-Golgi and plasma membrane.
How are vesicles targeted to specific locations?
Through SNARE proteins: v-SNAREs on vesicles and t-SNAREs on target membranes mediate specific docking and fusion.
What is the function of Rab proteins in vesicle delivery?
Rab GTPases regulate vesicle docking, tethering, and fusion by interacting with tethering factors.
How does the cytoskeleton assist vesicle transport?
Vesicles are transported along microtubules by motor proteins: dynein (retrograde) and kinesin (anterograde).
What is the role of actin filaments in vesicle transport?
Actin filaments facilitate short-range transport and vesicle movement near the plasma membrane.
What is the signal hypothesis in protein targeting?
The signal hypothesis proposes that proteins have a signal peptide guiding them to their proper cellular compartment, such as the ER.
How are proteins targeted to the mitochondria?
Proteins contain mitochondrial targeting sequences (MTS) recognized by TOM/TIM complexes for import.
What are second messengers, and give examples?
Second messengers are intracellular signaling molecules like cAMP, IP3, and calcium ions that amplify external signals.
How do receptor tyrosine kinases (RTKs) transmit signals?
RTKs undergo autophosphorylation upon ligand binding, initiating downstream signaling cascades like the MAPK pathway.
What is the role of G-proteins in signaling?
G-proteins act as molecular switches, relaying signals from G-protein-coupled receptors (GPCRs) to intracellular pathways.
How do kinase cascades amplify cellular signals?
Kinase cascades phosphorylate multiple downstream targets in a sequential manner, amplifying the signal.
What are integrins, and what is their role?
Integrins are transmembrane receptors that connect cells to the extracellular matrix and mediate adhesion and signaling.
