MCB 2000 Exam 3 – Uconn Final Exam
with Complete Correct Answers 2025-
2026 Updated.
What determines the specificity? - Answer Receptor-hormone noncovalent interactions
(similar to enzymes)
How is amplification achieved? - Answer Activating more and more proteins in a cascade
-Do not need a high [signal]
-G proteins
-Second messengers
-Activation of kinases & phosphatases
How is the integration of metabolic pathways achieved? - Answer -2 hormones can work
together (glucagon, epinephrine) or oppose one another in a pathway (glucagon, insulin)
-Liver: goal is to maintain glucose concentration
-Glucagon stimulates glycogen degradation and gluconeogenesis (synthesis) in liver to maintain
blood glucose during an overnight fast
Synergistic and antagonistic effects—which hormones work together? Which oppose? What is
the effect on metabolic pathways? - Answer -Work together: glucagon, epinephrine
-Oppose one another: glucagon, insulin
What are the mechanisms for signal termination? - Answer 1. Phosphodiesterase degrades
cAMP
2. Galpha-subunit of G-protein has catalytic activity
(GTPase: Hydrolysis of GTP → GDP)
3. Hormone-Receptor interaction: noncovalent
(Hormone will eventually dissociate)
Hormone receptor interactions: Binding characteristics - Answer -Specificity
-Noncovalent
, -Calcium ion
-DAG
-IP3
Second messengers - What is their function? - Answer Hormone --> second messenger -->
changes in cell
G-protein: what is its function? - Answer -Protein that is associated with receptor (very
loosely)
-3 subunits
-GDP bound - inactive
-GTP bound - active
-Alpha subunit (GTP) separates from Beta & gamma: activates membrane-bound enzyme
Adenyl cyclase - how does it become active? - Answer -Transmembrane, integral
-Catalytic membrane: faces internal part of the cell (Needs access to ATP: polar, charged)
-Alpha subunit moves laterally to interact with adenylyl cyclase (noncovalently)
-Noncovalent interactions trigger the production of 2nd messenger
What does adenyl cyclase produce? - Answer ATP --> cAMP
Protein kinase A - how does it become active? - Answer cAMP binds to protein kinase A
-2 catalytic subunits
-2 regulatory subunits
-Subunits interact in the absence of cAMP: kinase inactive
-Each regulatory subunit binds a molecule of cAMP
-Interactions between catalytic & regulatory weaken
-Catalytic subunits become active
Phosphodiesterase—what reaction does it catalyze? What are the effects of caffeine? - Answer
-Hydrolysis reaction to break the cyclical bond
-cAMP→ AMP → phosphorylated to ADP → phosphorylated to ATP
with Complete Correct Answers 2025-
2026 Updated.
What determines the specificity? - Answer Receptor-hormone noncovalent interactions
(similar to enzymes)
How is amplification achieved? - Answer Activating more and more proteins in a cascade
-Do not need a high [signal]
-G proteins
-Second messengers
-Activation of kinases & phosphatases
How is the integration of metabolic pathways achieved? - Answer -2 hormones can work
together (glucagon, epinephrine) or oppose one another in a pathway (glucagon, insulin)
-Liver: goal is to maintain glucose concentration
-Glucagon stimulates glycogen degradation and gluconeogenesis (synthesis) in liver to maintain
blood glucose during an overnight fast
Synergistic and antagonistic effects—which hormones work together? Which oppose? What is
the effect on metabolic pathways? - Answer -Work together: glucagon, epinephrine
-Oppose one another: glucagon, insulin
What are the mechanisms for signal termination? - Answer 1. Phosphodiesterase degrades
cAMP
2. Galpha-subunit of G-protein has catalytic activity
(GTPase: Hydrolysis of GTP → GDP)
3. Hormone-Receptor interaction: noncovalent
(Hormone will eventually dissociate)
Hormone receptor interactions: Binding characteristics - Answer -Specificity
-Noncovalent
, -Calcium ion
-DAG
-IP3
Second messengers - What is their function? - Answer Hormone --> second messenger -->
changes in cell
G-protein: what is its function? - Answer -Protein that is associated with receptor (very
loosely)
-3 subunits
-GDP bound - inactive
-GTP bound - active
-Alpha subunit (GTP) separates from Beta & gamma: activates membrane-bound enzyme
Adenyl cyclase - how does it become active? - Answer -Transmembrane, integral
-Catalytic membrane: faces internal part of the cell (Needs access to ATP: polar, charged)
-Alpha subunit moves laterally to interact with adenylyl cyclase (noncovalently)
-Noncovalent interactions trigger the production of 2nd messenger
What does adenyl cyclase produce? - Answer ATP --> cAMP
Protein kinase A - how does it become active? - Answer cAMP binds to protein kinase A
-2 catalytic subunits
-2 regulatory subunits
-Subunits interact in the absence of cAMP: kinase inactive
-Each regulatory subunit binds a molecule of cAMP
-Interactions between catalytic & regulatory weaken
-Catalytic subunits become active
Phosphodiesterase—what reaction does it catalyze? What are the effects of caffeine? - Answer
-Hydrolysis reaction to break the cyclical bond
-cAMP→ AMP → phosphorylated to ADP → phosphorylated to ATP
