Chapter 11: Cell Signaling

Question 1

Local Signaling (between cells)

Answer 1

Requires direct contact (i.e. gap junctions) or cell-cell recognition (exchange of signaling molecules)

Paracrine signaling (with messenger molecules like growth factors that travel short distances to tell cells to do stuff)

Synaptic signaling (with neurotransmitter release in response to electric signal)

Poorly understood in PLANTS

Question 2

Long distance signaling

Answer 2

Involves hormones that travel longer distances through the circulatory system

Cells receiving this hormone messages must have the appropriate receptors to “read” them

Called endocrine signaling in ANIMALS

Question 3

3 stages of cell signaling

Answer 3

Reception (cell receives msg via its membrane receptors and changes shape

Transduction (the amplification of signals to better coordinate/regulate the cell’s response); has multiple steps that often involve shape changes in proteins

Response (may involve one or more different response options [including termination of the signal] depending on how efficiently the message was processed and whether the signal processing involving branching)

Question 4

3 types of membrane receptors

Answer 4

G protein coupled receptor (transmembrane receptor that binds inactive g proteins from the cell cytoplasm to inactive GDP to make active GTP in the cell membrane)

Receptor tyrosine kinases (membrane receptors that attach phosphates to themselves and tyrosines; linked to cancer when they don’t work right)

Ion/Ligand-gated channel receptors (controls ion levels to facilitate shape changes in receptors that receive signals); creates hydrophilic tube through which ions through)

Question 5

Kinase

Answer 5

Enzyme that catalyzes the transfer of a (negatively charged) phosphate group from ATP and another protein (to activate the proteins)

Question 6

INTRAcellular receptors

Answer 6

found in the cytoplasm or nucleus of target cells

small hydrophobic chemicals (like steroid and thyroid hormones) pass the membrane to get here to help the activated receptor participate in transcription/gene expression

Question 7

Phosphorylation (1 of 2 types of transduction)

Answer 7

Part of transduction/mechanism for regulating protein activity

Occurs when “kinases” transfer phosphates from ATP to protein (to activate the protein. For action)

Occurs in a cascade like falling dominos

the reverse (dephosphorylation) facilitated by “phosphatases”

Question 8

Second Messenger Molecules (2 of 2 types of transduction)

Answer 8

NOT proteins

molecules or ions that spread through diffusion

Two types: cyclic AMP and calcium ions

Question 9

Apoptosis

Answer 9

Cell receives message to die

One of the most elaborate signaling pathways

Question 10

Scaffolding proteins

Answer 10

Increase efficiency of transduction by bring receptors/proteins to the same regions so they can interact/participate in signal amplification/propagation