Microbio Chapter 5- Microbial Metabolism Flashcards
(53 cards)
What are enzymes?
Biological catalysts
-Speed up reactions without increase of temperature
Specific (Lock and key model or enzyme-substrate complex)
How do enzymes speed up reactions?
Reduce activation energy needed
What are most enzymes composed of?
Proteins + cofactor
What is the protein portion of an enzyme called?
Apoenzyme
What is a cofactor?
Non-protein portion of an enzyme
What is it called if the cofactor is an organic molecule?
Coenzyme
What factors influence enzyme activity?
- Temperature
- pH
- Substrate
- Inhibitors
What is the optimal temperature for most disease-producing bacteria in the human body? (Optimum)
35C - 40C
-Reaction rate increases as temp increases until too heated
What happens to enzymatic reactions if the temperature is elevated beyond the optimum?
Rate of reaction is reduced and the enzyme is denatured
How does pH affect enzymes?
If pH is too low or too high the reaction rate declines
What happens to enzymatic reactions when the pH is above/below the optimum value?
Reaction rate is reduced and enzyme is denatured
How does substrate concentration affect enzymes?
Increased substrate concentration = increased rate of reaction
What happens when all active sites on the enzyme are filled?
Maximum rate of reaction is reached
-Reaction rate can’t be any faster
What are the two types of inhibitors?
Competitive and Non-competitive
How do competitive inhibitors prevent the enzyme from functioning?
Inhibitor occupies the active site
-Compete with normal substrate for the active site spot
Why are competitive inhibitors able to occupy the active site?
Its shape/chemical structure is similar to normal substrate
-It mimics
What is an example of a competitive inhibitor?
Sulfanilamide
What is Sufanilamide?
Antibacterial drug
What does Sulphanilamide mimic?
PABA (para-aminobenzoic acid)
What is PABA’s function?
Produces folic acid
What happens when Sulphanilamide inhibits?
Folic acid cannot be synthesized
–> DNA/RNA is not synthesised resulting in cell death
How do non-competitive inhibitors prevent the enzyme from functioning?
They interact with another part of the enzyme causing the active site to change its shape making it nonfunctional
What do non-competitive inhibitors play a role in?
Feedback inhibition
What is feedback inhibition?
Stops a cell from wasting chemical resources by preventing it from making a substance
