Chapter 9 Flashcards
An example of a ligand for a cytoplasmic receptor is
a steroid
Which type of receptor undergoes a conformational change upon activation
all of them do
What is an example of a GPCRs and the role of a second messenger
adrenaline
What is an example of receptor kinases
growth factors
What is an example of ligand-gated ion channels
nervous system
What are the four steps in cell signaling
receptor activation, signal transduction, response, termination
When a signal binds to a receptor what happens to the receptor
it changes shape, this reaction is reversible/transient
What is an endocrine signal
hormone signal to distant cells usually via circulatory system
What is a paracrine signal
affects nearby cells
What is an autocrine signal
affect the cells that made them
What is a contact-development signal
touch to activate
Membrane receptors: location, bind what, example
in the plasma membrane, bind polar ligands, insulin
Intracellular receptors: location, bind what, example
in the cytoplasm, bind nonpolar ligands that diffuse across the PM, estrogen (lipids)
What is another name for an intracellular receptor
cytoplasmic receptor
Caffeine _______ brain activity and _______ adenosine, which _______ brain activities
increases, blocks, slows down
Caffeine binds ______ activating the receptor
without
Active cells signal ______ the cell causing a ____ response
inside, new
What does heterotrimeric mean? What does monomeric mean?
3 different subunits
one subunit
How are heterotrimeric G proteins, such as Gα, and
the monomeric G proteins such as Ras different
They are structurally different and are activated by different
signaling pathways
G proteins are active when they are bound to
GTP
Is the term “G-protein” just a shorter name for a G-protein coupled receptor?
No
You strip off any proteins on the cell surface by using a protease. Now when you add a specific signaling molecule, the cell still responds. Why?
the receptor is in the interior of the cell
What component of the pathway is not a protein kinase
Ras
What is a components of the pathway of GTPase
Ras
In a flight or fight response which molecules are activated by a shape change when adrenaline is present?
receptor, protein kinase A
Would you expect phosphorylation of glycogen synthase to activate or inactive the enzyme?
Inactivate
A mutation that inactivates the ability of the receptor to interact with the G protein would?
inhibit the fight-or-flight response
Suppose a mutation occurred that resulted in the G protein losing its ability to hydrolyze GTP to GDP. How would this mutation affect the fight-or-flight response?
It would over-activate the fight-or-flight response
In the fight-or-flight signaling pathway, suppose there is a mutation that results in the permanent activation of PKA. How would this mutation affect the response?
It would over-activate it
Supposed you are a research scientist studying the fight-or-flight response in cultured liver cells. You inject these cells with cAMP. What outcome would you predict?
Increased glucose production from glycogen
Suppose you are a research scientist studying the fight-or-flight response in cultured liver cells. You inject these cells with adrenaline. What outcome would you predict?
No change in glycogen mobilization
Which component of the cytoskeleton is the smallest in diameter?
Microfilaments
GCPRs: bind to, activate what
bind to heterotrimeric G proteins
ligand binding to GPCRs activates G proteins
Heterotrimeric G proteins (like RAS)
Membrane-associated proteins with 3 subunits
Bind GDP (inactive) to GTP (active)
Is activated adenylyl cyclase an effectivor
yes
What is the pathway for GCPRs
activated receptor
activate adenylyl cyclase
converts ATP into cAMP which activates kinase A
Kinase A phosphorylates proteins in the heart muscle
Is cAMP a first messenger or second messenger
Second
What is the difference between a first messenger and a second messenger
first messenger-ligand signal
second messenger-small, soluble, non-protein molecule, relay the initial signal to target molecules inside the cell
Difference between active form and inactive form
Active form-interaction and turned on
Inactive form-no interaction, turned off
Second messengers:
Affect many processes
Amplify signal
Regulate target enzymes
What are the four steps in termination?
Transient (temp. bound signal)
Devactives itself
Get rid of cAMP
Loses phosphates
Ion channel receptors:
Channel proteins that allow ions to enter or leave a cell
In a ligand-gated channel, how is it activated
nerotransmitters
What are 3 effects of a signal
opening ion channels
changing enzyme activity
differential gene transcription
Cell signaling over a long distance is known as:
A. autocrine signaling.
B. paracrine signaling.
C. endocrine signaling.
D. juxtacrine signaling.
endocrine signaling
How many subunits make up a G protein?
A. three
B. two
C. four
D. The number is variable.
three (It is heterotrimeric, meaning that it has three subunits that are all different!)
What happens to the alpha subunit of a G protein with GDP attached?
A. It re-assembles with the beta and gamma subunits.
B. It no longer activates an effector protein.
C. It re-associates with the G protein–coupled receptor.
D. All of these answer options are correct.
All correct
Which one of the following initiates signal termination?
A. the reduction of signal amplification
B. the shut down of transcription
C. the release of signal molecules from their receptors
D. the shut down of translation
the release of signal molecules from their receptors
Which of the following is characterized by a cell releasing a signal molecule into the
environment, followed by a number of cells in the immediate vicinity responding?
A. juxtacrine signaling
B. autocrine signaling
C. paracrine signaling
D. endocrine signaling
paracrine signaling
One of the major categories of receptors in the plasma membrane reacts by forming dimers,
adding phosphate groups, and then activating relay proteins. Which type does this?
A. G protein-coupled receptors
B. ligand-gated ion channels
C. steroid receptors
D. receptor kinases
receptor kinases
The receptors for a group of signaling molecules known as growth factors are often
A. ligand-gated ion channels.
B. G protein-coupled receptors.
C. receptor kinases.
receptor kinases
An inhibitor of phosphodiesterase activity would have which of the following effects?
A. decrease the amount of cAMP in the cytoplasm
B. block the activation of G proteins in response to epinephrine binding to its receptor
C. prolong the effect by maintaining elevated cAMP levels in the cytoplasm
D. block the activation of protein kinase A
prolong the effect by maintaining elevated cAMP levels in the cytoplasm
The epithelial cell junctions that, respectively, 1) restrict the extracellular movement of
molecules across an epithelium, 2) maintain tissue integrity and strength, and 3) allow the
passage of small molecules between adjacent cells are:
A. gap junctions, desmosomes, and tight junctions
B. desmosomes, tight junctions, and gap junctions
C. tight junctions, gap junctions, tight junctions
D. gap junctions, tight junctions, desmosomes
E. tight junctions, desmosomes, gap junctions
tight junctions, desmosomes, gap junctions
Which of the following cell junctions is designed in such a manner to create a “tube”
connecting one cell to the other such as in cardiomyocytes?
A. gap junctions
B. tight junctions
C. desmosomes
gap junctions
Cadherin is a component of which two types of cell junctions?
A. Adheres junctions
B. Desmosomes
C. Gap junctions
D. B+C
E. A+B
A+B
What is the difference between a tissue and organ?
Cells make tissues and tissues make an organ, and different organs present in the body
make an organ system. The tissue is capable of performing the simple task while organs are
known for operating the complex one.
In an ion-gated channel what activates the channel? What breaks down the activator?
Acetylcholine
Acetylcholinesterase
