Cellular signaling

20 important questions on Cellular signaling

What are external signals?

are converted to responses within the cell.

What are short-long distance?

- local signaling: target cell and secretory cells are nearby
- long distance signaling: hormones secreted into body fluids and binds to target cells.

Which three stages of cell signaling are there?

Reception, transduction, response
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What is the function of plasmamembrane receptors?

highly specific binding for signal molecules or shape change of plasmamembrane receptors after binding whit these receptors.

Which plasma membrane receptors are there?

G- protein-coupled receptor
Receptor tyrosine kinases
ligand-gated ion channels

How works a G-protein-coupled receptor?

it work with the help of a G-protein. the G-protein acts as an on/off switch: if GDP us bound to the G-protein, the G-protein is active.

How works Receptor tyrosine kinases?

it is a dimer that attached phosphates to tyrosines. it can trigger multiple signal transduction pathway ate once.

How works a ligand-gated ion channel?

it acts as a gate when the receptor changes shape. when a signal molecule binds as a ligand to the receptor, the gate allows specific ions, such as NA+ or CA2+, through a channel in the receptors.

Which second messengers do they have?

cyclic AMP (cAMP), Cyclic GMP (cGMP), CA2+, inositol triphosphat (IP3), diacylglycerol (DAG).

What is CA2+ (second messenger)?

increasing the cytosolic concenctration of CA2+ cause many responses in animal cells, including muscle cell contraction secretion of certain substances, and cell divion. (they lay in the ER).

What is inositol triphosphat (IP3)?

functions as a intermediate between certain signaling molecules and a sbusequent second messenger, CA2+, by causing a rise in cytoplasmatic CA2+ concentration.

What is diacylglycerol (DAG)?

DAG is produced by the cleavage of the phospholipid PIP2 in the plasma membrane.

What types of responses are there?

Protein synsthesis an activation of enzymes.

What does the response "Protein synsthesis"?

in the nucleus transcription factor becomes active and make a mRNA.

What doe the response "activation of enzymes"?

activates enzymes in the cytoplasm.

What regulation has a response?

amplification, specifity, overall efficiency, termination of the signal.

What does amplification (in response)?

elaborate enzyme cascades amplify the cell's response to a signal

What is the specifity (in response)?

- some signal molecule only can give a signal on one protein.
- sometimes more diffrent signal molecules can give different responses ( same receptor other reponse).

What is the overall efficiencey (in response)?

a scaffolding protein binds to the membrane receptor. the scaffolding protein has three diffrent protein kinases.

What is the termination of the signal (in response)?

- if a ligand concentrtion falls, fewer receptors will be bound
- unbound receptors revert to an inactive state.

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