Topic 2- Enzymes Flashcards
What is Metabolism
The chemical reactions of an organism
Give 2 types of Metabolism, and distinguish between them
Catabolism and Anabolism
Catabolism - ‘breakdown’ reactions
Anabolism - ‘build-up’ reactions
What is the theory of Enzyme action
- Enzyme + substrate
- Enzyme - substrate complex
- Enzyme - product complex
- Enzyme + product
What is the definition of an Enzyme
A biological catalyst that speeds up the rate of reaction, without using itself up
How do Enzymes have specific shapes
It is determined by their tertiary structure
What is the Active site
The particular part of the enzyme molecule where the reaction takes place
How do Enzymes affect the Activation Energy
It lowers it, which allows the reaction to take place
What are Enzymes to a substrate
Specific
Give 2 models which explain how Enzymes work
Lock and key
Induced fit
Give similarities between the Induced fit model and the lock and key model
The substrate binds to the active site of the enzyme, which forms an Enzyme-Substrate complex
The Substrate leaves as 2 products after the reaction
Give a main difference between the Induced fit model and the lock and key model
In the Lock and Key model, the Substrate fits exactly to the Enzymes active site
In the Induced fit model, the Enzyme moulds itself around the substrate
Of the 2 models of Enzyme action which is more useful and why
Induced-fit model as it better explains the way in which activation energy is lower in catabolic reactions
How does an increase in Substrate concentration effect Enzyme activity
As you increase the substrate concentration, enzyme activity increases, as there is a higher chance of collisions meaning more Enzyme substrate complexes
What happens to Enzyme activity when Substrate concentration bypasses the Enzyme concentration
Enzyme activity does not increase, as all the active sites have been taken up by Substrates
How does an increase in Enzyme concentration effect Enzyme activity
An increase in enzyme concentration increases the rate of reaction, as there is more Enzyme substrate complexes formed
Why may a enzyme concentration graph level off at high Enzyme concentrations
There is insufficient substrate
How does a change to the optimum pH effect Enzyme activity
It will decrease Enzyme activity as the active sites of the enzymes are altered by changes in pH
Past the optimum pH, what happens to the bonds inside an enzyme
Ionic bonds in the tertiary structure of a protein will be disrupted
What is pH
A measure of hydrogen ion concentration
How does an increase in temperature effect Enzyme activity
It causes an exponential increase in Enzyme activity. This is due to the increase in temperature providing more kinetic energy for more collisions between Enzymes and substrates
What happens to the Enzyme past the Optimum temperature
The bonds that hold the tertiary structure of the enzyme molecules are broken and so the active site loses its complementary shape
What is a Co-factor
An enzyme with a non-protein part attached
What is a coenzyme
An organic molecule that are often derivatives of vitamins
How do Cofactors function
They either influence the shape of an enzyme or they participate in the enzymatic reaction
What is the difference between Competitive and Non-Competitive Inhibition
Competitive inhibitors closely resemble the structure of the substrate and so competes for the active site
Nom-competitive inhibitors don’t resemble the substrate and so bind to a part of the enzyme away from the active site
Of the 2 inhibitors, which of them changes the shape of the Enzyme permanently
Non-competitive inhibitors
Out of the Enzyme not having an inhibitor, competitive inhibitor and a non-competitive inhibitor, which increases the Enzyme activity the most
The enzyme with no inhibitor
What is the effect of a competitive inhibitor
If there is a high substrate concentration, the effect of the inhibitor is reduced
What is the effect of a non-competitive inhibitor
As the inhibitor is not competing for the active site, an increase in substrate concentration will have no effect on the inhibitor
What is Adsorption
The enzymes are attached by weak forces to an inert substance such as glass or a matrix
What is entrapment
The enzymes are trapped within polymers such as Alginate beads or microspheres
What is Encapsulation
The enzymes are trapped inside a selectively permeable membrane such as Nylon
What is Cross-Linkage
The enzymes are bonded covalently to a matrix, such as cellulose, as a sequence of chemical reactions
What are some commercial advantages of Enzyme immobilisation
Production can take place continuously
The product is enzyme-free, so purification costs are reduced
The enzyme remains separate from the reaction mixture
The enzymes stability is improved, meaning it remains active over a greater range of pH and temperatures
What are some advantages and disadvantages of Adsorption as a method of Enzyme immobilisation
Advantages - Easy to Immobilise and so relatively cheap
Disadvantages- Enzymes can be washed away ; some active sites may be blocked by the absorptive material
What are some advantages and disadvantages of Cross-Linking as a method of Enzyme immobilisation
Advantages- enzymes securely bonded, so not washed away; resistant to pH and temperature changes
Disadvantages- Active sites may be blocked by binding chemicals; significant distortion of some active sites during binding process
What are some advantages and disadvantages of Encapsulation as a method of Enzyme immobilisation
Advantages- Enzymes not bound, so active sites are not blocked and activity is not adversely affected
Disadvantages - Substrate has to diffuse through mesh; some enzymes may leak out through mesh
What are some advantages and disadvantages of Entrapment as a method of Enzyme immobilisation
Advantages - Enzymes cannot leak out; since enzymes not bound, active sites are not blocked
Disadvantages - Resistance to substrates diffusing into a gel matrix and products diffusing out
How do Biosensors use immobilised enzymes
To detect or monitor a particular molecule
What do glucose test strips utilise and what do they do
They utilise the enzyme glucose oxidase, which specifically acts on glucose in the presence of oxygen to yield glauconite acid and hydrogen peroxide
