AP Biology Unit 4 Review 1

In cell signaling, how is the flow of specific ions

regulated?

• Opening and closing of ligand-gated channels

• Transduction

• Cytoskeleton rearrangement

• Endocytosis

Many signal transduction pathways use second messengers to:

• transport a signal through the lipid bilayer portion of the plasma membrane.

• relay a signal from the outside to the inside of the cell.

• relay the message from the inside of the membrane throughout the cytoplasm.

• amplify the message by phosphorylating proteins.

A signal molecule that binds to a plasma-membrane protein is a

• ligand
• second messenger
• protein kinase
• receptor protein

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

• phosphorylation cascade
• cAMP
• signal receptors
• phosphatase

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

Signal amplification is most often achieved by

• an phosphorylation cascade

• binding of multiple signals

• branching pathways

• action of adenylyl 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.

The three stages of cell signalling are

• paracrine, local, and synaptic
• reception, transduction, and response
• transcription, translation, and folding
• alpha, beta, and gamma

What type of transmembrane receptor is being shown?

• G-protein receptor
• tyrosine kinase receptor
• gated ion channel

Homeostasis mechanisms...

• keep everything exactly the same.

• usually operate by positive feedback systems.

• act to keep the internal environmental conditions outside the normal range

• is the ability to maintain a relatively stable internal environment