5.2 properties of enzymes Flashcards
all enzymes are _________
protein
enzymes are made denatured by ___________
high temperature (<40°C)
why are enzymes made denatured by high temperature?
protein molecules are damaged by heat
enzymes work best at what temperature?
about 37°C (human body temperature)
what are the four variables in enzyme activity?
temperature; pH; enzyme concentration; substrate concentration
what are the effects of low temperature on enzyme activity?
low temperature = low kinetic energy possessed by the substrate and the enzyme molecules
low kinetic energy > low collisions > low rate of reaction > reduced enzyme activity > enzyme is inactive
what is optimum temperature?
the temperature at which an enzyme works the fastest in
what causes the active site to change its shape?
when the temperature goes beyond the optimum temperature
what would an enzyme be deemed as when its active site changes shape?
the enzyme is said to be denatured
the substrate can no longer bind to the active site of the enzyme
denaturation is a _____ process
permanent
inactive enzymes can regain ___________ when temperature increases
catalytic function
when an enzyme is denatured, its catalytic function is lost _________
permanently
most enzymes are in their correct shape at a pH of ___
7
what happens to the enzyme if the pH is too acidic or alkaline?
enzyme is denatured; cannot catalyse its reaction
rate of enzyme activity is ______ to enzyme concentration
proportional
concentration of substrate must be in ______
excess
describe the steep line of a graph
- rate of reaction is proportional to the substrate concentration
- enzyme activity increases with substrate concentration as there are still available active sites on enzyme molecules
describe the long neutral line of a graph
- rate of reaction is no longer influenced by substrate concentration
describe the long neutral line of a graph
- rate of reaction is no longer influenced by substrate concentration
- all the available active sites on enzymes are saturated with substrate molecules
- additional substrate molecules need to compete with each other to bind to the active sites of enzymes
- at this point reaction happens at a constant rate
(enzyme concentration is constant)
characteristics of enzymes
- made of proteins
- not changed by reaction
- can be reused
- only small amount is needed
- specific
- sensitive towards temperature and pH
- can be inhibited (eg mercury, plumbum)
- cofactors are sometimes needed (eg magnesium, vitamin B, vitamin K)
