Action of Enzymes Flashcards
what do catalysts do
lower the activation energy
by providing an alternative reaction pathaway
what do enzymes do
speed up chemical reactions by acting as biological catalysts
enzymes can either be ….. or …….
Intracellular ( within cells)
or
extracellular ( outside cells)
example of intracellular enzyme
catalase
breaks down h2o2 into harmless hydrogen and o2
examples of extracellular enzymes
Amylase and trypsin
Amylase- found in the mouth and secreted by salivary glands, helps to catalysing the break down of starch into maltose
Trypsin- catalyses the hydrolysis of peptide bonds
- produced by the pancrease
- secreted by small intestine
what determines the shape of the active site
the enzyme’s tertiary structure
when a substrate bonds to the enzyme’s active site, what is formed
an enzyme substrate complex( ESC)
this is the bit that lowers the activation energy
2 reasons why an ESC lowers the activation energy
1) if 2 substrate molecules need to be joined attaching tl the enzyme holds them more closely together, reducing any repulsion between the molecules
2) if an enzyme is catalysing a break down reaction, fitting into the active site puts a strain on the bonds in the substrate, meaning that substrate molecule breaks more easily
lock and key model
and why didngt this model last long
lock= enzyme
key=substrate
new evidence showed that ESC change shape slightly to fit to the active site more tightly, locking the substrae tighter.
hence the- induced fit theory
what does the induced fit theory help show
why enzymes are so specific and only bond to one particular substrate
all you have to say is: as the substrate binds the active site changes shape slightly to fit the substrate more closely
what is an enzyme PRODUCT complex
when the substrate breaks
and leaves the active site as products
