Enzymes Flashcards
What are enzymes
Globular proteins which helps catalyse metabolic reactions in cells and organisms
Extracellular enzyme
Work outside cells
Intracellular enzyme
Remains and work within cells
Factors affecting enzyme activity
1) Temperature
2) pH
3) Substrate concentration
4) Enzyme concentration
Explain more about how temperature affects enzyme activity
An increased in temperature, Increase in kinetic energy, Increase in number of collisions, Increase is the formation of enzyme substrate complex
Explain more about how pH affects enzyme activity
- affects shape of enzyme (active site becomes inactive)
- affects ionic bond (changes the charges of amino acids)
Explain how substrate concentration affects enzyme activity
Increase in SC, Increase collisions, Increase possibility of formation of enzyme-substrate complex
Explain how enzyme concentration affects enzyme activity
Increase in concentration of enzyme, Faster rate of reaction
What are inhibitors
Molecules which alters the rate of reaction of enzymes and are reversible
Explain competitive inhibitor
- compete for binding in the active site
- can still be overcome through increase in concentration of substrate
Explain non-competitive inhibitor
- inhibitor binds at allosteric site which alters the shape of active site
- increase in concentration of substrate doesn’t affect
Explain what is meant by enzyme specificity
Enzymes recognise a small group of substrate molecules because the active site has specific shape and chemical properties
Lock and key model
Substrate will just bind to the active site
Induced-fit model
Substrate don’t exactly fit into active site, but because enzymes are globular proteins which are flexible so are able to change the shape of the active site to match the substrate
Km and enzymes
The lower the value of km, the greater the affinity of the enzymes
what is km value
measure of enzyme affinity at which enzyme functions at hald its max rate
experiment of formation of pxygen
1) fill in tube with hydrogen peroxide
2) put small potato cubes in the tube
3) Wait until you see bubble formation
4) use gas syringe to measure amount of oxygen produced
experiment to measure rate of disapperance of starch
1) add amylase solution to starch suspension in a test tube
3) take samples of reacting mixture in regular time intervals and test for presence of starch using iodine in potassium iodide solution
starch: blue black
no: orange brown
