Chapter 21: Development

Which of these is a signal molecule? C B D E A

A

Which of these is a receptor molecule? B A C D E

B

________ aid in the coordination of the activities of adjacent animal cells. Desmosomes Gap (communicating) junctions Keratin fibers Tight junctions Plasmodesmata

Gap (communicating) junctions

A signal molecule is also known as a(n) _____. initiator protein key ligand receptor

ligand

A signal transduction pathway is initiated when a _____ binds to a receptor. G protein cyclic AMP signal molecule calmodulin tyrosine kinase

signal molecule

Which of these cell junctions form a barrier to the passage of materials? keratin fibers tight junctions desmosomes (anchoring junctions) plasmodesmata gap (communicating) junctions

tight junctions Tight junctions form a barrier that prevents fluids from moving between cells.

Which of these is the second of the three stages of cell signaling? gene activation reception binding of a neurotransmitter to a plasma membrane receptor transduction cell response

transduction