MCB 252 – Exam 1 Study Guide with Key Concepts and
Practice Questions
The most abundant class of phospholipid in animal cell membranes with a hydrophobic tail
composed of two fatty acyl chains that are esterified to the two hydroxyl groups in the glycerol
phosphate and a polar head group attached to the phosphate group is called: - correct answer
✔✔ phosphoglycerate
Generally, the phosphoglycerates are ______ molecules - correct answer ✔✔ amphipathic
In general, the exoplasmic face of the plasma membrane is directed: - correct answer ✔✔ away
from the cytosol
A ligand usually binds to a specific ___ that results in the activation of a signal transduction
pathway. - correct answer ✔✔ receptor
In paracrine signaling, the signaling molecule: - correct answer ✔✔ acts on cells in close
proximity to the secreting cell
The super family of proteins that RAS belongs to is: - correct answer ✔✔ GTPase
Name the family of proteins that by physically interacting with Ras enhances the intrinsic
GTPase activity of Ras in the RTK-mediated signal transduction pathway. - correct answer ✔✔
GAP
Name the GEF that activates Ras in the RTK-mediated signal transduction pathway - correct
answer ✔✔ Sos
,The adaptor protein GRB2 interacts with the active RTK receptor using its: - correct answer ✔✔
SH2 domain
Which is the following protein kinase that directly phosphorylates MAP kinase in the Ras/MAPK
signal transduction pathway? - correct answer ✔✔ MEK
T/F: The switch from RasGDP to RasGTP, which is induced by Sos requires the cellular
concentration of GTP to be much greater than the cellular concentration of GDP - correct
answer ✔✔ True
T/F: The individual eye within a compound eye pf Drosophila is called Ommatidium - correct
answer ✔✔ True
T/F: The BOSS protein present on the membrane of the R8 cell activates the Sevenless receptor
on the R7 progenitor cell - correct answer ✔✔ True
What would be the fate of R7 differentiation in a fly with an inactive Sevenless receptor and a
constitutively active Ras in the progenitor R7 cell? - correct answer ✔✔ R7 progenitor cell will
differentiate into R7 neuron.
Which is the subunit in the trimeric G-protein that physically interacts with GTP - correct answer
✔✔ Alpha subunit
Name the enzyme that synthesizes cAMP - correct answer ✔✔ adenylyl cyclase
In the GPCR pathway, the active effector functions as a ____ to inactivate G protein - correct
answer ✔✔ GAP
T/F: in the GPCR pathway, cAMP primarily acts as a second messenger - correct answer ✔✔
True
, T/F: The GTP-bound active G-alpha protein ALWAYS activates the effector protein - correct
answer ✔✔ False
NFkB is a: - correct answer ✔✔ Transcription factor
What is/are the key post-translational modifications on IK-B that result in its release from NF-KB
and subsequent degradation - correct answer ✔✔ Phosphorylation and polyubiquitination
among the different types of protein domains that are mentioned below, one of them is not
generally recognized by E3 ligases as a signal for polyubiquitination.
Nuclear Localization Signal
Hydrophobuc patch of amino acids
PEST sequence
KEN-box
D-box - correct answer ✔✔ Nuclear Localization Signal
Which of the following is the ubiquitin enzyme that primarily provides substrate specificity
during ubiquitin-mediated protein degradation? - correct answer ✔✔ E3 ubiquitin-protein
ligase
Which region or sub-unit of the 26S proteasome has the protease activity - correct answer ✔✔
B-subunits of the 20S core
Which unit of the 26S proteasome plays crucial roles in the ATP dependent unfolding of the
proteins that are targeted for degradation? - correct answer ✔✔ 19S cap unit
Practice Questions
The most abundant class of phospholipid in animal cell membranes with a hydrophobic tail
composed of two fatty acyl chains that are esterified to the two hydroxyl groups in the glycerol
phosphate and a polar head group attached to the phosphate group is called: - correct answer
✔✔ phosphoglycerate
Generally, the phosphoglycerates are ______ molecules - correct answer ✔✔ amphipathic
In general, the exoplasmic face of the plasma membrane is directed: - correct answer ✔✔ away
from the cytosol
A ligand usually binds to a specific ___ that results in the activation of a signal transduction
pathway. - correct answer ✔✔ receptor
In paracrine signaling, the signaling molecule: - correct answer ✔✔ acts on cells in close
proximity to the secreting cell
The super family of proteins that RAS belongs to is: - correct answer ✔✔ GTPase
Name the family of proteins that by physically interacting with Ras enhances the intrinsic
GTPase activity of Ras in the RTK-mediated signal transduction pathway. - correct answer ✔✔
GAP
Name the GEF that activates Ras in the RTK-mediated signal transduction pathway - correct
answer ✔✔ Sos
,The adaptor protein GRB2 interacts with the active RTK receptor using its: - correct answer ✔✔
SH2 domain
Which is the following protein kinase that directly phosphorylates MAP kinase in the Ras/MAPK
signal transduction pathway? - correct answer ✔✔ MEK
T/F: The switch from RasGDP to RasGTP, which is induced by Sos requires the cellular
concentration of GTP to be much greater than the cellular concentration of GDP - correct
answer ✔✔ True
T/F: The individual eye within a compound eye pf Drosophila is called Ommatidium - correct
answer ✔✔ True
T/F: The BOSS protein present on the membrane of the R8 cell activates the Sevenless receptor
on the R7 progenitor cell - correct answer ✔✔ True
What would be the fate of R7 differentiation in a fly with an inactive Sevenless receptor and a
constitutively active Ras in the progenitor R7 cell? - correct answer ✔✔ R7 progenitor cell will
differentiate into R7 neuron.
Which is the subunit in the trimeric G-protein that physically interacts with GTP - correct answer
✔✔ Alpha subunit
Name the enzyme that synthesizes cAMP - correct answer ✔✔ adenylyl cyclase
In the GPCR pathway, the active effector functions as a ____ to inactivate G protein - correct
answer ✔✔ GAP
T/F: in the GPCR pathway, cAMP primarily acts as a second messenger - correct answer ✔✔
True
, T/F: The GTP-bound active G-alpha protein ALWAYS activates the effector protein - correct
answer ✔✔ False
NFkB is a: - correct answer ✔✔ Transcription factor
What is/are the key post-translational modifications on IK-B that result in its release from NF-KB
and subsequent degradation - correct answer ✔✔ Phosphorylation and polyubiquitination
among the different types of protein domains that are mentioned below, one of them is not
generally recognized by E3 ligases as a signal for polyubiquitination.
Nuclear Localization Signal
Hydrophobuc patch of amino acids
PEST sequence
KEN-box
D-box - correct answer ✔✔ Nuclear Localization Signal
Which of the following is the ubiquitin enzyme that primarily provides substrate specificity
during ubiquitin-mediated protein degradation? - correct answer ✔✔ E3 ubiquitin-protein
ligase
Which region or sub-unit of the 26S proteasome has the protease activity - correct answer ✔✔
B-subunits of the 20S core
Which unit of the 26S proteasome plays crucial roles in the ATP dependent unfolding of the
proteins that are targeted for degradation? - correct answer ✔✔ 19S cap unit
