AP Biology signal transduction key terms

What is signal transduction?

The process by which a cell responds to external signals, converting them into cellular responses.

Define receptor.

A protein molecule that receives chemical signals from outside a cell, initiating a response.

True or false: All signal receptors are located on the cell membrane.

False, because some receptors are intracellular, located in the cytoplasm or nucleus.

Difference between autocrine and paracrine signaling.

Autocrine signaling affects the same cell that releases the signal, while paracrine signaling affects nearby cells.

Fill in the blank: G-protein coupled receptors activate __________.

G-proteins that transmit signals inside the cell.

What is a ligand?

A molecule that binds to a specific receptor, triggering a response in the target cell.

Define second messenger.

Small molecules that relay signals received by receptors, amplifying the signal within the cell.

True or false: Phosphorylation always activates proteins.

False, because phosphorylation can also inhibit protein function.

What role does cyclic AMP play?

It serves as a second messenger in many signal transduction pathways.

Difference between endocrine and exocrine signaling.

Endocrine signals travel through the bloodstream, while exocrine signals are released into ducts.

What is amplification in signal transduction?

The process where one signal molecule results in the activation of many target molecules.

Define feedback inhibition.

A regulatory mechanism where the output of a process inhibits its own production.

Fill in the blank: __________ are proteins that bind to and help activate G-proteins.

G-protein coupled receptors.

What is apoptosis?

Programmed cell death that can be triggered by signal transduction pathways.

True or false: All signaling pathways result in immediate changes in gene expression.

False, because some pathways may lead to delayed responses.

What is the function of protein kinases?

Enzymes that add phosphate groups to proteins, usually activating them.

Define signal integration.

The process where multiple signaling pathways converge to produce a unified cellular response.

Difference between intracellular receptors and cell-surface receptors.

Intracellular receptors bind ligands that can cross the cell membrane; cell-surface receptors bind external ligands.

Fill in the blank: __________ is a key player in the signaling pathway of steroid hormones.

Intracellular receptors.