Enzymes Flashcards
What are enzymes?
Biological catalysts
What type of protein makes up enzymes?
Globular
How do enzymes catalyse reactions?
They reduce activation energy so reactions can occur at lower temperatures
Explain how the formation of an enzyme-substrate complex lowers activation energy
- Attaching substrate molecules reduces repulsion
- Fitting substrate puts strain on substrate’s bond
Explain how an increase in temperature increases enzyme activity
- More heat = More kinetic energy
- Enzymes more likely to collide
- Enzymes have more energy so more successful collisions
How does the ‘Induced Fit’ model differ from the ‘Lock and Key’ model?
- Idea that active site changes shape slightly to accommodate substrate
How does an enzyme denature when the temperature is too high?
Bonds holding active site together break, changing active site’s shape
How does a non-optimal pH affect enzyme activity?
H+ or OH- ions disturb ionic bonds and hydrogen bonds that hold enzymes tertiary structure
What are cofactors?
Non-protein substances that allow enzymes to work
How do cofactors work?
They help enzyme and substrate bond together
Are cofactors used up in reactions?
NO
What are coenzymes?
Cofactors that are organic molecules
What is competitive inhibition?
When molecules with similar shapes to substrate compete to bind to active site
What is non-competitive inhibition?
When molecules bind to an enzyme’s allosteric site, deforming the active site
What influences if inhibitors are reversible or non-reversible?
Strength of bonding
What is a metabolic pathway?
A series of connected metabolic reactions which catalyse each other
What is product inhibition?
Where a reaction produces a product which inhibits an enzyme
What is end product inhibition?
Where the final product in a metabolic pathway inhibits an enzyme from earlier on in the pathway
How is end product inhibition useful?
It regulates metabolic pathways and controls the quantity of end product
Are product and end product inhibition reversible or irreversible?
Reversible
Why are product and end product inhibition reversible?
When levels of product drop, inhibition levels also fall so enzymes can function again
