Epinephrine Pathway and Cell Signaling

Flashcards covering the epinephrine pathway, ligand-gated ion channels, and steroid hormone signaling.

What is epinephrine based on receptor location?

Epinephrine is hydrophilic because its receptor is on the cell surface.

What role does adenylyl cyclase play in the epinephrine pathway?

Adenylyl cyclase converts ATP into cAMP.

What is a second messenger and what is it in the context of epinephrine?

A second messenger is a small molecule that spreads a signal inside the cell. cAMP is the second messenger.

Why is a phosphorylation cascade used in signaling?

It amplifies the signal, making the response bigger and faster.

What activates the G protein in the signaling pathway?

It becomes active when GDP is replaced with GTP.

Are signals hydrophilic or hydrophobic? Why?

Hydrophilic, because they bind to receptors on the cell surface and can’t cross the membrane.

What happens to the receptor when acetylcholine binds?

It changes shape and opens the ion channel.

What is the direct response after the ion channel opens?

Na⁺ flows into the cell, causing depolarization.

Why do ions need channels to pass through membranes?

They are charged and cannot pass through the hydrophobic membrane.

How is the signal turned off in ion channels?

The ligand is removed or broken down, so the channel closes.

Why is there no membrane receptor needed for steroid hormones?

Because steroids are nonpolar and diffuse through the membrane.

What happens if no receptor is present for a steroid hormone?

Nothing happens because the hormone cannot bind.

What is the ultimate cellular response to steroid hormones?

Gene expression is activated, producing proteins.

What is the transduction difference between steroid hormones and epinephrine?

Steroids do not use a cascade, while epinephrine uses a signaling cascade with second messengers.

How does the speed of steroid signaling compare to that of ion channels?

Steroid signaling is slower because it involves gene expression, while ion channels are faster because ions move immediately.