B M 4 : Enzyme Action Flashcards
What are enzymes and what do they do?
Biological catalysts
- speed up chemical reactions by acting as biological catalysts
At what levels do enzymes catalyse metabolic reacts?
Cellular level (respiration) And for the organism as a whole (digestion on mammals)
At can enzymes affect? Give an example
The structures in an organism
- they’re Involved in the production of collagen, important protein in the connective tissue of mammals
Where can enzyme action take place?
-intercellular (within cells)
OR
-extracellular (outside cells)
What are enzymes classes as?
Proteins
Which part of the enzyme does the substrate molecule bind to?
Active wire, which has a specific shape
Why are enzymes highly specific?
Due to their tertiary structure
What do enzymes lower?
The activation energy of a reaction
What’s activation energy?
And what’s it often provided as?
The amount of energy that needs to be supplied to the chemicals before the reaction will start
-heat
What’s it form when a substrate fits into an enzymes active site?
An enzyme-substrate complex
What causes enzymes to lower the activation energy?
The formation of an enzyme-substrate complex
One reason Why an enzyme-substrate complex lowers the activation energy?
- if two substrate molecules need to be joined, being attached to an enzyme brings them closer together
- reducing any repulsion between the molecules so they can bond easily
Another reason why an enzyme-substrate complex lowers the activation energy
If enzyme catalysts a breakdown reaction, putting into the active site puts strain on bonds in the substrate
- so substrate molecule breaks up more easily
Lock and key model?
- substrate fits into enzymes active site
- enzyme-substrate complex formed
- substrate broken down products released after reaction
- enzyme is unchanged after reaction
Does the lock and key model give the full story?
No
What does new evidence show?
The enzyme-substrate complex changes shape slightly to complete the fit
- locks substrate more tightly to the enzyme
What’s the induced fit model?
- substrate fits into enzyme active site
- as substrate binds the active site changes shape slightly
- enzyme-substrate complex formed
- products released
What do enzymes properties relate to?
Their tertiary structure
Are enzymes very specific ?
Yes
Why are enzymes specific?
Because only one complementary substrate will fit into the active site
What determines the enzymes active site?
The tertiary structure
Do all enzymes have different tertiary structure and so different active sites
Yes
What does it mean if tertiary structure is altered?
Shape of active site will change
- enzyme substrate won’t fit active siren
- so enzyme-substrate complex can’t be formed
- enzyme can’t carry out its function
How can the tertiary of the enzyme be changed?
By changes in pH or temperature
What’s the primary structure of a protein determined by?
A gene
- so If a mutation occurs in that gene, it could change the tertiary structure of the enzyme produced
