Chem 153A Final Learning Objectives
Week 7 {Latest Updated 2026/2027}
Questions and Answers (Graded A+) -UCLA
What's a futile cycle? How are they prevented? - correct answer when two metabolic
pathways run simultaneously in opposite directions (at same rates??) and have no
overall effect/benefit other than to dissipate energy in the form of heat
- no evolutionary benefit
=>prevent by regulating metabolism via irreversible steps in pathway (deltaG<0,
favorable)
What is anabolism - correct answer synthesize biomolecules for cell maintenance,
growth, and reproduction
What is catabolism - correct answer degrade biomolecules to create smaller
molecules and energy
What's a committed step? - correct answer an irreversible step in a metabolic
pathway, often regulated by regulatory enzymes
- deltaG is negative =>favorable
How do you identify regulatory enzymes? Where (in a pathway) do they tend to
occur? - correct answer - present at irreversible steps
- found usually at or near branch point in branched pathway
, Chem 153A Final Learning Objectives
Week 7 {Latest Updated 2026/2027}
Questions and Answers (Graded A+) -UCLA
(deltaG either always negative OR always positive (coupled), cant be near equilibrium
(deltaG=0) cuz thats reversible)
What's feedback inhibition? - correct answer a negative feedback loop from a later
product to an earlier enzyme in the same pathway, allosteric inhibition
(how dynamical systems can be attuned through network feedback)
Understand how product choice can be regulated in a branched pathway - correct
answer A<==>B-->C-->F<==>G<==>H
^-->D<==>E
(H and E products are inhibitors for steps C to F, and C to D respectively)
If there's an excess of H, it'll inhibit C to F step, pushing for more product formation
of E. and vice versa
What's a positive feedback loop in enzyme regulation? What's the design rationale
for this kind of loop? - correct answer (an increase in A leads to EVEN MORE A)
- slower to reach steady state
- more bistable dynamic response (either full ON or full OFF)
=>for big decision/commitment/event (e.g. birth and oxytocin)
What's a negative feedback loop in enzyme regulation? What's the design rationale
for this kind of loop? - correct answer an increase in B leads to an eventual decrease
(or no more increase) in B
Week 7 {Latest Updated 2026/2027}
Questions and Answers (Graded A+) -UCLA
What's a futile cycle? How are they prevented? - correct answer when two metabolic
pathways run simultaneously in opposite directions (at same rates??) and have no
overall effect/benefit other than to dissipate energy in the form of heat
- no evolutionary benefit
=>prevent by regulating metabolism via irreversible steps in pathway (deltaG<0,
favorable)
What is anabolism - correct answer synthesize biomolecules for cell maintenance,
growth, and reproduction
What is catabolism - correct answer degrade biomolecules to create smaller
molecules and energy
What's a committed step? - correct answer an irreversible step in a metabolic
pathway, often regulated by regulatory enzymes
- deltaG is negative =>favorable
How do you identify regulatory enzymes? Where (in a pathway) do they tend to
occur? - correct answer - present at irreversible steps
- found usually at or near branch point in branched pathway
, Chem 153A Final Learning Objectives
Week 7 {Latest Updated 2026/2027}
Questions and Answers (Graded A+) -UCLA
(deltaG either always negative OR always positive (coupled), cant be near equilibrium
(deltaG=0) cuz thats reversible)
What's feedback inhibition? - correct answer a negative feedback loop from a later
product to an earlier enzyme in the same pathway, allosteric inhibition
(how dynamical systems can be attuned through network feedback)
Understand how product choice can be regulated in a branched pathway - correct
answer A<==>B-->C-->F<==>G<==>H
^-->D<==>E
(H and E products are inhibitors for steps C to F, and C to D respectively)
If there's an excess of H, it'll inhibit C to F step, pushing for more product formation
of E. and vice versa
What's a positive feedback loop in enzyme regulation? What's the design rationale
for this kind of loop? - correct answer (an increase in A leads to EVEN MORE A)
- slower to reach steady state
- more bistable dynamic response (either full ON or full OFF)
=>for big decision/commitment/event (e.g. birth and oxytocin)
What's a negative feedback loop in enzyme regulation? What's the design rationale
for this kind of loop? - correct answer an increase in B leads to an eventual decrease
(or no more increase) in B
