Cell Signaling Flashcards
cell-surface receptor binding/ endocrine and paracrine signaling
extracellular signaling
nuclear receptors
intracellular signaling
molecular switches, signal integration
signaling mechanisms
Intracellular signaling pathways can be activated by an extracellular signal molecule (T or F)
True
Extracellular signal molecules can bind to only cell-surface receptors (T or F)
False, can also bind to intracellular receptors
4 forms of intercellular signaling
- Endocrine - hormones into bloodstream
- Paracrine - into extracellular fluid locally
- Synaptic - NTs electronically along axon
- Contact-Dependent - cell-to-cell communication
adrenaline, cortisol, estradiol, insulin, testosterone, thyroid
example of hormones
epidermal GF, platelet-derived GF, nerve GF, histamine, nitric oxide
example of local mediators
acetylcholine, GABA
example of neurotransmitters
delta
example of contact-dependent signal molecule
Contact-dependent signaling controls nerve-cell production in the fruit fly Drosophila (T or F)
True
Extracellular signals always act fast (T or F)
False, can act slow too
Animal cells rely on multiple extracellular signals (T or F)
True
Various responses in various cells can be induced by the same signal molecule (T or F)
True
GABA triggers smooth muscle relaxation in a blood-vessel wall (T or F)
False, nitric oxide does this
Signal molecules that bind to nuclear receptors are usually small and hydrophobic (T or F)
True
The steroid hormone cortisol acts by activating a transcription regulator (T or F)
True
3 classes of cell-surface receptors
- Ion-Channel-Coupled
- G-Protein-Coupled
- Enzyme-Coupled
Tasks done by intracellular signaling proteins (4)
- Relay
- Amplify
- Integrate
- Distribute the Incoming Signal
What are the two types of intracellular signaling proteins that act as molecular switches?
- Signaling by protein phosphorylation
- Signaling by GTP-Binding proteins
Positive and negative feedback mechanisms exist in biological switching networks (T or F)
True
Structure of G-Protein-Coupled Receptors
polypeptide chain that transverses the plasma membrane seven times with the cytoplasmic part of the receptor bind to a G protein inside the cell
An activated G-protein disassembles into 2 signaling components (alpha and beta) (T or F)
True
After activation, what happens to the G-protein alpha-subunit?
It switches itself off by hydrolyzing its bound GTP to GDP
What happens in heart pacemaker cells?
A G Protein-linked receptor couples activation to K+ channel opening
G Protein-linked receptors can cause release of second messenger signaling molecules (T or F)
True
Cyclic AMP (cAMP) increase rapidly in response to an intracellular signal in nerve cells (T or F)
False, an extracellular signal
What synthesizes cyclic AMP?
adenylyl cyclase
What degrades cyclic AMP?
cyclic AMP phoshodiesterase
What does adrenaline stimulate?
Glycogen breakdown in skeletal muscle cells
What activates gene transcription?
A rise in cAMP concentration
Phospholipase C activates two signaling pathways called?
- Diacylglycerol
- Inositol 1,4,5-trisphosphate (IP3)
Cell Responses Mediated by Phospholipase C Activation (3)
- Vasopressin
- Acetylcholine (pancreas and smooth muscle)
- Thrombin
What does fertilization of an egg by a sperm trigger?
An increase in cytosolic Ca++
What does calcium binding do?
Changes the shape of the calmodulin protein
What activates the Ras protein?
Docking intracellular signaling proteins on an activated receptor tyrosine kinase
What does Ras activate?
a MAP-kinase signaling pathway
What does receptor tyrosine kinases (RTKs) activate?
the PI-3-kinase-Akt signaling pathway
Activated Akt promotes cell death (T or F)
False, cell survival
Growth factor binding to enzyme receptor kinases can stimulate cells to grow (T or F)
True
Both G Protein couples receptors and receptor tyrosine kinases activate multiple intracellular signaling pathways (T or F)
True
The Notch receptor is NOT a transcription regulator (T or F)
False, it is
In plants, the ethylene signaling pathway turns on genes by removing what?
inhibition
Intracellular signaling proteins can integrate multiple signals (T or F)
True
