46 terms

LC Biology 2.2a Enzymes

Biological catalysts
Enzyme structure
Proteins made up of long chains of amino acids folded into a specific shape. Any factor affecting enzyme shape affects enzyme activity.
A substance that speeds up a chemical reaction but is not used up in that reaction.
Enzyme Functions
Control cellular reactions and Enable reactions to occur with less energy.
Enzymes are Specific
A different enzyme is needed for each reaction as different enzymes have particular shapes to match each substrate.
Cell activity
Is determined by which enzymes are active at a certain time. Can be altered by removing specific enzymes and synthesising new ones.
Breaks down disaccharides to monosaccharides.
Breaks down starch into maltose.
Digests complex sugars and starches.
Active Site
The part of the enzyme to which the substrate binds. Each site fits only one substrate molecule.
Lock and Key Model
Substrate fits perfectly into active site of enzyme. (Explains Enzyme Specificity)
Induced Fit Model
Shape of the active site is slightly changed to allow substrate to bind to enzyme.
Factors affecting Enzyme Activity
Enzyme and Substrate concentrations, Temperature, pH
Effect of Enzyme Concentration
Rate of reaction increases with enzyme concentration, provided substrate is in excess.
Effect of Substrate Concentration
Rate of reaction increases with substrate concentration until all active sites are in use. (After which there is no change)
Effect of Temperature
Increasing temperature causes more movement, thus causing a higher collision frequency and therefore enzyme action.
37 C
Temperature at which human enzymes work best
When an enzyme has lost its shape and therefore cannot function
Heat Denaturation
Permanent distortion of the active site caused by heat, rendering the enzyme inactive.
Optimum Temperature
Temperature at which the Rate of Reaction is at a maximum.
Critical Temperature
Point at which heated enzymes, if cooled, will regain their activity.
Optimum pH
pH at which the Rate of Reaction is at a maximum.
Enzyme Inhibitor
A substance that changes the shape of an enzyme and makes it unable to bind to a substrate
Hydrogen Peroxide
Substrate used in Enzyme Activity Experiments
Enzyme used in Enzyme Activity Experiments
pH buffers
used to maintain constant pH in Enzyme Activity Experiments
Water baths
used to maintain constant temperatures in Enzyme Activity Experiments
How rate of reaction is measured
the volume of foam that is produced in a set period of time
How enzyme is denatured
source of enzyme (celery) is boiled for 5 minutes
Unboiled enzyme
Control used in Heat Denaturation of an Enzyme Experiment
A vessel in which products are made by biological organisms or their enzymes
Immobilised Enzymes
Enzymes which are attached to each other, to insoluble materials or enclosed in a membrane or gel.
Advantages of immobilised enzymes
Easy harvesting of product / Easy recovery of enzymes for Reuse / Greater enzyme stability.
Enzyme is attached to an insoluble surface e.g. ceramics / glass / plastics.
Membrane Enclosure
Enzyme is enclosed in a porous membrane.
Gel Entrapment
Enzymes are trapped in the fibres of the gel.
Direct Cross Linking
Enzyme molecules are joined to each other to form a polymerised enzyme.
enzyme used in Enzyme immobilisation experiment
Sodium alginate
used in Enzyme immobilisation experiment to immobilise the yeast
Calcium chloride solution
used in Enzyme immobilisation experiment to harden the bound yeast into balls
substrate used in Enzyme immobilisation experiment
product made in Enzyme immobilisation experiment
Making fructose
Glucose Fructose by Glucose isomerase
Used in soft drinks.
Enzymes used to change penicillin into new antibiotics.
Sewage Treatment
Recycled and Reused enzymes are used instead of bacteria.