Cell Communication
What structures allow direct cell-to-cell communication?
Gap junctions (animals) and plasmodesmata (plants)
What are the three stages of cell signaling?
Reception, transduction, response
Where are receptors for estrogen found?
Intracellularly (cytoplasm/ or nucleus)
What is a "response" in cell signaling?
Changes in gene expression or cell function
What happens if protein phosphatase is mutated?
The signal would not shut off
What molecules are used for long-distance signaling in both plants and animals?
Hormones
Where would a water-soluble (polar) receptor be located?
What type of receptor activates a G protein when a ligand binds?
GPCR
How can one signal molecule (ligand) cause a massive cellular response?
Signal amplification
What happens if protein kinase is mutated?
The pathway would not activate
What is the difference between paracrine and synaptic signaling?
paracrine = local regulators; synaptic = neurotransmitters across a synapse
What is the main role of second messengers in a signaling pathway?
Second messengers amplify the signal
What happens when a ligand binds to a ligand-gated ion channel?
The ligand-gated ion channel opens or closes
What is transcription and translation?
Transcription makes RNA (mRNA); translation makes protein from mRNA
Can a mutated receptor still bind a ligand?
Possibly not due to its altered receptor structure
True or False: Insulin signaling is an example of local signaling
False
How do protein kinases and protein phosphatases differ?
Protein kinases phosphorylate; protein phosphatases dephosphorylate
What ensures signaling specificity in a signal transduction pathway?
Specific ligand-receptor binding
The final molecule in a signaling pathway can act as a transcription factor
True
What do "activate" and "inhibit" mean in a signaling cascade?
Activation = phosphorylation; inhibition = dephosphorylation
What type of signaling allows hormones to reach distant target cells in animals?
Endocrine signaling via the circulatory system
In a signal transduction cascade, what does the term "signal" refer to?
A ligand (chemical signal)
How can neurons participate in both local and long-distance signaling?
Neurons can use synaptic signaling and long-distance calcium waves after an axon injury
What does it mean for a gene to be turned "on" or "off"?
Gene on = protein made; gene off = protein not made
What would happen to a signal transduction pathway if the receptor’s intracellular domain were mutated, even though the ligand can still bind normally?
The signaling pathway would fail to activate because the receptor could bind the ligand, but the signal could not be relayed to downstream molecules inside the cell.