BIO Chapter.9
What do synaptic signaling and paracrine signaling have in common?
Cells please a signal that affects neighboring cells
A G-protein coupled receptor associates with a G protein that contains how many subunits?
3
Some anti-cancer drugs block signal transduction pathways activated by growth factors. Which of the following would be a good target for such a drug?
An inhibitor of a protein kinase cascade
During exposure to elevated glucose, a yeast cell will increase its uptake of glucose. Describe the mechanism by which the yeast sense the extracellular glucose.
By glucose binding to glucose receptors
When the concentration of a ligand is equal to the Kd which of the following is true?
Half of the receptors are bound to ligands
When receptors coupled to phospholipase C are activated, calcium levels in the cytosol increase when ______
IP3 binds to ligand-gated channels on the endoplasmic reticulum, releasing calcium
When a cell makes a cell membrane bound growth factor that binds to receptors on neighboring cells causing them to proliferate this is an example of:
contact-dependent signaling
What happened next after insulin bind to a G-protein coupled receptor (GPCR)?
The G-protein loses GDP and gains GTP becoming activated
Following its initial activation, how does a G protein become inactivated?
The G-protein, a subunit GTP, is hydrolyzed to GDP allowing reassociation of the G-protein a subunit and dimer
Estrogen is a lipid soluble hormone that can easily cross membranes. Knowing this, what can be concluded about estrogen receptors?
The receptors would be found inside the cell
In some cases, just a few hormone molecules binding to the surface of a cell can trigger a very large response because
The signal is amplified by activation of enzymes that each catalyze multiple reactions
Patients who have type 2 diabetes no longer respond normally to insulin. Which statement best explains this symptom?
Their cells express less insulin receptor
What do G-protein coupled, enzyme-linked, and ligand-gated ion channel receptors have in common?
They change their conformation when bound to a hormone
If you add the plant hormone auxin to one side of a plant, the cells exposed to the auxin elongate. If you measured auxin levels in plant cells exposed to light, what you would you expect to find?
They would be lower, causing the plant to bend towards the light.
Patients who have type 2 diabetes no longer express genes when exposed to insulin. How might this phenomenon be explained?
Transcription factors normally activated by insulin remain off
A phosphatase is capable of dephosphorylating molecules. What would this enzyme do in a signal transduction pathway that used a kinase cascade?
Turn off the cascade
Smooth muscle cells in the airways relax while those in the blood vessels contract in response to the hormone epinephrine. What would you expect to be different in these two types of cells exposed to epinephrine?
Types of proteins expressed
A hormone binds a receptor and activates the cAMP signal transduction pathway ultimately leading to the cell response. If you wanted to develop a drug to block this pathway, the drug would need to inhibit _____
adenylyl cyclase
When epinephrine binds to its G-protein linked receptor ____ is activated producing ___.
adenylyl cyclase, cAMP
The production of second messengers in signal transduction offers at least two advantages, speed and
amplification
Programmed cell death is known as ____
apoptosis
When a cell secretes a growth factor that binds to receptors on its own membrane preventing it from proliferating this is an example of
autocrine signaling
When cAMP is produced in a cell, it will then ______
bind to a repressor of protein kinase A
Phospholipase C hydrolyzes a membrane phospholipid to produce ____
both IP3 and diacylglycerol
The process through which cells can detect and respond to signals in their extracellular environment is
cell communication
A key is placed into a keyhole then turned and the door opens. When considering the components of cell signaling, the action of turning the key would best correspond to
conformational change in the receptor once bound to the hormone
When epidermal growth factor binds to its _____________ the receptor phosphorylates itself, triggering a signal transduction pathway.
enzyme-linked receptor
If the concentration of a ligand is 100x greater than the Kd of its receptor, ___ of the receptors with be bound to a ligand.
most
A substrate binding to an enzyme is most similar to a signal molecule binding to a
receptor
What do enzyme-linked receptors and growth factor receptors have in common?
Both possess kinase activity when bound to a hormone
When a cell responds to a signal it sent, this is an example of
Autocrine signaling
Epinephrine blocks the contraction of muscles in the airways. Which of the other activities of epinephrine is most likely to be regulated by the same type of pathway?
Inhibition of saliva production in salivary glands
When sodium ions move from one cardiac muscle to an adjacent cell, causing them t contract in unison, this is an example of
direct intercellular signaling
Hormones are released from one cell and act on other cells in distant organs and are thus example of
endocrine signaling
When insulin is secreted from the pancreas and acts on muscle cells to increase glucose uptake, this is an example of
endocrine signaling
Diabetics can be given the ______ insulin which binds to receptors on cells throughout the body increasing glucose uptake.
hormone
After being fed glucose, a cell increases its intracellular glucose concentrations by
increasing membrane glucose transporters
P3 binds to _____ receptors
ligand-gated Ca2+ channel
When a neurotransmitter released from one neuron binds to a ______ on a second neuron, that neuron depolarizes and fires.
ligand-gated ion channel
The molecule directly responsible for breaking down cAMP to inactive AMP is ______
phosphodiesterase
Adenylyl cyclase is to cAMP as ________ is to IP3
phospholipase C
After estrogen binds to receptors, these estrogen receptors gain ______ activity.
transcription factor
