2.1.4 Enzymes Flashcards
example of enzymes that catalyzes intercellular reactions
catalase - helps decomposition of hydrogen peroxide into water and oxygen
dextranase is an enzyme that catalyses the breakdown of specific bonds in dextran
so why does dextranase catalyse the breakdown of dextran but not amylose?
Dextran binds to the active site of the dextranase enzyme
so the dextran makes the active site shape change quickly
amylose is not able to change the active site as much so can’t be catalysed
examples of enzymes that catalyze extracellular reactions
Amylase- carbohydrase into maltose in the saliva
trypsin- catalyzes hydrolysis of peptide bonds of protiens in the saliva
On a graph showing the rate of an enzyme activity why is the calculated rate likely to be different to the true initial rate of reaction?
Inital rate is likely to be greater due to
a higher concentration of substrate
so is more likely to enter the active site.
why would there be a difference in the shape of curves of an enzyme at 25degrees vs 37 degrees
At lower temperature their is less kinetic energy
so fewer successful collisions into the active site
so more time is needed for product to be formed
and not all the substrate will react in the time given
What do enzymes increase the rate of?
Reactions by lowering the activation energy
Enzymes are biological catalysts that facilitate chemical reactions in living organisms.
What is the active site of an enzyme?
The area of the enzyme where the reaction with the substrate takes place
The active site is crucial for the enzyme’s specificity and function.
What is meant by the term specificity in enzymes?
Enzymes are specific to substrates they bind to, meaning only one type of substrate fits into the active site
This specificity is essential for the precise functioning of metabolic pathways.
What model describes the structural alteration of the enzyme when substrate binds?
Induced fit model
This model suggests that the active site of the enzyme changes shape to better fit the substrate.
How does enzyme concentration affect the rate of enzyme-controlled reactions?
Rate of reaction increases as enzyme concentration increases until substrate concentration becomes the limiting factor
Beyond a certain point, more enzymes do not increase the reaction rate.
How does substrate concentration affect the rate of enzyme-controlled reactions?
Rate of reaction increases with substrate concentration until enzyme concentration becomes the limiting factor
This relationship highlights the importance of both enzyme and substrate availability.
What happens to the rate of reaction as temperature increases?
Rate of reaction increases up to the optimum temperature, then decreases above that temperature
Enzymes have a specific temperature range where they function best.
Define an inhibitor in the context of enzyme activity.
A substance which slows down or stops a reaction by affecting the binding of substrate to the enzymes
Inhibitors can impact metabolic pathways significantly.
What are the two types of inhibitors?
Reversible and irreversible inhibitors
The distinction is based on whether they permanently alter enzyme function.
What is an example of an irreversible inhibitor?
Heavy metal ions such as mercury and silver
These substances disrupt enzyme activity by altering the structure of the active site.
How do competitive inhibitors affect enzyme activity?
They compete with substrate for the active site, decreasing enzyme activity
The rate of product formation decreases, but the total amount of product remains the same.
What is the effect of increasing substrate concentration on competitive inhibitors?
Increases in substrate concentration can reverse the effect of competitive inhibitors
This is due to substrate outcompeting the inhibitor for the active site.
How do non-competitive inhibitors work?
They bind to an allosteric site, changing the shape of the active site and preventing substrate binding
Increasing substrate concentration does not affect non-competitive inhibition.
What role do coenzymes play in enzyme activity?
They are organic cofactors that facilitate substrate binding to the enzyme
Many coenzymes are derived from vitamins.
What is an example of a coenzyme?
NAD derived from niacin
NAD acts as a hydrogen acceptor in various biochemical reactions.
What are activators in the context of enzymes?
Inorganic metal ions that temporarily bind to enzymes and alter their active site
Activators can enhance enzyme activity.
What is a prosthetic group?
A non-polypeptide unit that is tightly and permanently attached to a protein
An example is the haem group in hemoglobin, which binds oxygen.
