4.2 Diagnostic

Which of the following transduction signal molecules pass through the plasma membrane and bind to the intracellular receptors that move into the nucleus and function as transcription factors to regulate gene expression?

• epinephrine

• growth factors

• yeast mating factors

• testosterone, a steroid hormone

What determines whether a cell is a target cell for a particular signal molecule?

• phosphorylation cascade
• cAMP
• signal receptors
• phosphatase

Which of the following is a chemical message that usually travels through the bloodstream to target cells?

• hormone
• local regulator
• endocrine cell

A cell converting a chemical signal into a cellular response is known as __.

• energetics

• transduction

• ligand response

• transformation

Signal amplification is most often achieved by

• an phosphorylation cascade

• binding of multiple signals

• branching pathways

• action of adenylyl cyclase

What do secondary messengers, like cAMP, do?

• transport a signal through the lipid bilayer

• relay & amplify a signal from the outside to the inside of the cell

• relay & amplify a message from the inside of the membrane throughout the cytoplasm

• dampen the message

What does a protein kinase do?

• removes phosphates
• transfers phosphates from ATP to proteins
• activates an enzyme

Which of the following can activate a protein by transferring a phosphate group to it?

• cAMP
• G Protein
• protein kinase
• protein phosphatase

The general name for an enzyme that transfers phosphate groups from ATP to a protein is __________.

• protein dehydrogenase

• protein kinase

• protein phosphatase

• peptidase

• protein cyclase

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because __________.

• they are species specific.

• the number of molecules used is small and fixed.

• they always lead to the same cellular response.

• they amplify the original signal manyfold.

• they counter the harmful effects of phosphatases.