2.5 Enzymes Flashcards
What is an enzyme?
A globular protein that acts as biological catalyst by speeding up the rate of a chemical reaction
What happens to enzymes when they catalyse a reaction?
They are not changed or consumed by the reaction
Can enzymes be reused?
Yes
What are enzymes typically named after?
The molecules they react with
What is the active site?
The region on the surface of the enzyme which binds to the substrate molecule
What are the two ways the active site and substrate complement each other?
Shape and chemical properties
What is capable of binding to a particular enzymes active site?
A specific substrate
Where do enzyme reactions typically take place?
In aqueous solution
What does the fact that enzyme reactions take place in aqueous solutions show about its position?
The substrate and the enzyme are randomly moving within the solution
What does an enzyme being in a fixed position do?
Serves to localise reactions to particular sites
What does enzyme catalysis need?
The substrate to be in close proximity with the active site
When is an enzyme-substrate complex formed?
When a substrate binds to the enzymes active site
How is an enzyme product complex created?
When the enzyme catalyses the conversion of the substrate into product
What happens after the enzyme product complex is created?
The enzyme and product dissociate
How can you increase the rate of enzyme catalysis?
By increasing the frequency of collisions
How can you increase the rate of collisions?
Increasing the molecular motion of the particles
Increasing the concentration of the particles
What are the shape and chemical properties of an active site dependent on?
The tertiary structure of the enzyme
What can cause an enzyme structure to be modified?
External factors like temperature and pH
How does temperature and pH affect enzymes?
They disrupt the chemical bonds which maintains the structure of the enzyme causing denaturation
What will a change to the structure of the active site do?
Negatively affect the enzymes capacity to bind to the substrate
What affects the rate of activity of an enzyme?
Temperature
pH
Substrate concentration
What does low temperature during a reaction result in?
Insufficient thermal energy for the enzyme catalysed reaction to happen
What does increasing the temperature do during a reaction?
Increases the speed and motion of both enzyme and substrate
Why does an increase in temperature result in higher enzyme activity?
Because a higher kinetic energy results in more collisions between the enzyme and the substrate
What happens at an optimal temperature?
The rate of enzyme activity will be at its peak
In terms of temperature what causes an enzyme stability to decrease and why?
Higher temperatures as the thermal energy disrupts the enzymes hydrogen bonds
What does changing the pH do to the enzyme?
Alter the charge of the enzyme and thus its solubility an overall shape
What does changing the shape or the charge of the active site do?
Stop its ability to bind to the substrate
What does moving out of an enzymes optimal pH do?
Stop its enzyme activity
What does increasing the substrate concentration do?
Increase the activity of a corresponding enzyme
What does having more substrates mean?
There is an increased chance of enzyme and substrate colliding and reacting in a given period
When talking about substrate concentration, what happens after a certain point?
The rate of activity will stop regardless of substrate levels because all enzymes will be bound and reacting
What is the shape of rate of reaction against temperature graph?
Slow gradient and steep decrease
What is the shape of rate of reaction against pH graph?
Equal rise to peak as downhill from peak
What is the shape of rate of reaction against substrate concentration graph?
Sharp increase then it plateaus
When designing an experiment to test the effect of factors affecting enzyme activity, what are the three key decisions?
Which factor to investigate?
Which enzyme/substrate reaction to use?
How to measure the enzyme activity?
When designing an experiment to test the effect of factors affecting enzyme activity, what are your choice of independent variables?
Temperature
pH
substrate concentration
Presence of inhibitor
When designing an experiment to test the effect of factors affecting enzyme activity, what are the two ways reactions are measured in accordance to?
The amount/rate of substrate decomposition or product formation
What are immobilised enzymes used for?
To be fixed to a static surface in order to improve the efficiency of the catalysed reaction
Why is separation of the product more easily achieved?
The enzyme remains attached to the static surface
How are enzymes used in biofuels?
To breakdown carbohydrates to produce ethanol-based fuels
How are enzymes used in medicine?
To identify a range of conditions like pregnancy or certain diseases
How are enzymes used in biotechnology?
In multiple processes like gene splicing
How are enzymes used in food production?
In the production and refinement of beers and dairy products
How are enzymes used in textiles?
In the processing of fibres
How are enzymes used in paper?
Assisting the pulping of wood for paper production
What is lactose?
A disaccharide of glucose and galactose
What can break down lactose?
Lactase
Where is lactose intolerance particularly high?
In asian, african and aboriginal populations
Why is lactose intolerance lower in europeans?
A mutation that maintains lactase production into adulthood
When do mammals show a decrease in lactase production?
After weaning
How can lactose free milk be produced?
By treating the milk with lactase
What is the process of using lactase for lactose free milk?
The lactase is purified by yeast or bacteria and then bound to an inert substance. the milk is then passed through this repeatedly
How are scientists trying to create a cow that produces lactose free milk?
By splicing the lactase gene in the cows genome so lactose is broken down before milking
What are the four advantages of lactose free milk?
It is a source of dairy for lactose free individuals
Ir is a means of increasing sweetness without artificial sweetners
A way of reducing crystillisation of ice cream
Reduces production time for cheeses and yogurts
