Why enzymes beat the hill

Science · Biochemistry & Molecular Biology · ages 18-20

Name ______________________ Date ____________

Which move belongs in the enzyme toolkit?
- Pushing molecules harder
- Lending protons at the critical instant
- Heating the whole cell
Why do uncatalyzed reactions crawl at body temperature?
- No substrate exists
- Few molecules can climb the barrier
- Water blocks all paths
A catalyst emerges from the reaction unchanged.
Circle one: True False
What does steadying the transition state do?
- Raises the starting valley
- Cools the surroundings
- Lowers the hilltop of the barrier
Why is tight substrate binding a poor strategy?
- It digs the valley deeper and raises the climb
- It uses up the enzyme
- It melts the active site
Why does equilibrium stay put?
- Both directions speed equally
- The enzyme picks a side
- Products leave faster
An enzyme doubles the forward rate. What happens to the reverse rate?
- It halves at once
- It stays frozen
- It doubles too
The active site molds around its substrate and strains it. What is this?
- Lock and key
- Induced fit
- Competitive blocking

Answer key

For grown-ups. Fold this page away before handing over the rest.

Lending protons at the critical instant · Proton lending at the right moment is one barrier lowering trick.
Few molecules can climb the barrier · Only a lucky few carry enough energy to summit the hill.
True · It lowers the toll on the road but takes no cut of the cargo.
Lowers the hilltop of the barrier · Binding the hilltop tight lowers the pass.
It digs the valley deeper and raises the climb · A deeper starting valley means a taller hill to climb.
Both directions speed equally · Equal speeding leaves the forward to reverse ratio unchanged.
It doubles too · The same lowered pass serves traffic in both directions.
Induced fit · Induced fit sharpens the grip by reshaping the site.