Enzymes Flashcards
metabolism
all the reactions of the body that occur in metabolic pathways
two types of metabolic pathways
catabolic
anabolic
anabolic and catabolic
ana-building of molecules
cata-breaking of molecules
what controls metabolism
enzymes
enzymes
globular proteins with hydrophilic r groups, so are soluble
what does enzyme sequence determine
hydrogen, disulphide, ionic bonds, which form the active site which the substrate binds to
enzymes are catalysts so therefore
speed up reactions
are not used up or changed
have a high turnover of product
enzymes are specific-they need
PH
enzyme/substrate concentration
temperature
ALL AT OPTIMUM
lock and key hypothesis
The substrate fits perfects into the enzyme active site due to its unique shape
theory of induced fit means
The shape of the active site changes to fit more perfectly around the substrate, putting pressure on the bonds in the substrate to lower the activation energy
lysozymes found
saliva, tears, mucus
lysozyme example enzyme
active site is a groove and sugars on cell walls fit
groove closes over sugars and shape change
lysozyme hydrolyses sugar bonds
cell well is weakened and bacteria absorbs water and burst
enzymes are either
intracellular or extracellular
intracellular enzymes with examples
inside solution- eg glucose breakdown enzymes in glycolysis(stage of respiration)
membrane bound- attached to cristae/ grana (transfers electrons and H+ in atp formation
extracellular enzymes
exocytosis secrets them & catalyses extracellularly
eg amylase- saprotrophic fungi/bacteria secrets it onto dead organisms and digests it
effect of temperature on enzymes
increased temp=increased kinetic energy=more collisions=faster rate
doubles for each 10 degree rise until around 36/40 degrees then decreases
why does rate of reaction decrease after optimum
heat breaks hydrogen bonds, enzyme is denatured
enzyme at low temp
enzyme is inactivated/low energy but with potential
effect of ph on enzymes
works best at optimum
small changes= small reversible changes
large changes= denaturation
charges on amino side chains are affected by h/oh ions
low ph= excess h+ attracted to negative charges
high ph=excess oh neutralise the positive charges
What does a buffer do?
Maintain a constant pH
effect of substrate concentration
if enzyme conc is constant= rate increases= substrate conc increases
low concentrations(limiting factor)= active site not at full capacity
high concentrations=no faster reaction, all AS occupied, new limiting factor LIKE TEMP OR PH
effect of enzyme concentration
enzymes are reusable so do not need a high conc
more enzymes= more active sites= faster rate
turn over number
no of substrate molecules one enzyme can turn into products
eg catalase= 40 million mecules per second for h2o2
What is inhibition?
Inhibition is when enzyme action is slowed down or stopped by another substance
