Cell Signalling Flashcards
The key difference between tyrosine kinase receptors and g-coupled protein receptors
Tyrosine kinase receptors are receptor-enzymes; the receptor itself has protein kinase activity. GPCRs, activate intracellular G proteins, triggering cascade events.
How auto phosphorylation occurs in tyrosine kinase pathway
autophosphorylation occurs when two receptor molecules, bound to their ligand, and phosphorylates tyrosine residues within the receptors themselves.
How do phosphorylated proteins contribute to the cellular response in the tyrosine kinase pathway?
Tyrosine kinase receptor changes the shape and function of these proteins.
What is the role of GTP in G-protein activation?
Binding G protein’s alpha subunit, cause to release GDP, activating sub alpha unit and enabling to interact with effector proteins
What is the role of adenylyl cyclase in the cyclic AMP secondary-messenger pathway.
Adenylyl cyclase converts ATP to cAMP, then cAMP activates protein kinase A, leading to cellular responses
What is the role of second messengers in cell signaling?
Amplify the signals by triggering cascade of intracellular events, leading to a more complex and coordinated cellular response
The role of cytochrome c in apoptosis
Cytochrome c, released from the mitochondria, activates caspases, initiating the apoptotic cascade and leading to cell death.
The relationship of excitable cells in membrane potential
Excitable cells (nerve and muscle cells) use the existing membrane potential to generate rapid, transient changes in that potential, creating electrical signals.
Why does potassium preferentially enter the cell more than the sodium ions?
Potassium has a smaller hydration shell, easier for it to lose water and binds to protein.
Why does the concentration gradient of K+ remain essentially constant despite its outward movement?
Only a tiny amount of K+ movement is needed to create a large change in membrane potential.
How nanotubes affects the intercellular communication within cells?
Nanotubes directly connect cells, enabling the transfer of signaling molecules and organelles.
The key difference between neurotransmitters and neurohormones
Neurotransmitters act locally and rapidly across synapses, while neurohormones travel through the bloodstream for broader, slower communication.
The key difference between antagonist and agonist
Antagonist inhibits receptor activity by blocking signal molecules while agonist stimulates receptor activity by mimicking the signal molecules
The key difference between lipophilic membrane vs lipophobic membrane
Lipophilic can pass through the plasma membrane while lipophobic cannot pass through the membrane
The role of phosphodiesterase in the Cyclic AMP Second-Messenger GPCR Pathway
Phosphodiesterase rapidly degrades cAMP, effectively terminating the cellular response when it’s no longer needed.
Why does potassium concentration gradient remain constant despite its movement out of the cell
Because only a small amount of K + ions are needed to leave to create an electrical gradient
How permeability of the plasma membrane affects membrane potential
The greater permeability, the greater the tendency the ion to drive membrane potential towards own equilibrium potential
Explain the forces that keep K+ high inside the cells
K+ high concentration inside the cells is maintained by the sodium-potassium pump, which actively transports K+ into the cell and Na+ out of the cell, against their concentration gradients
Explain why Na+ is low inside the cells despite a large concentration gradient inwards
Na+ is low inside cells because the sodium potassium pump actively expels Na+ out of the cell while transporting K+ in, maintaining the concentration gradient
Explain why Na+ is low inside the cells despite a large concentration gradient inwards
Na+ is low inside cells because the sodium potassium pump actively expels Na+ out of the cell while transporting K+ in, maintaining the concentration gradient
Why does the second messenger need to amplify its signal?
To ensure a strong and efficient cellular response to the initial stimulus
