enzymes Flashcards
what is the lock and key hypothesis
-substrate & enzyme have kinetic energy
-if substrate successfully collided with an enzyme molecule it forms an enzyme substrate complex
-substrate is either broken down or built up into the product molecule, forming an enzyme- product complex
-product leaves active site
-enzyme is now able to form another enzyme substrate complex
-small number of enzymes can convert a large number of substrates into products
what is the induced fit hypothesis
-substrate is not fully complementary in shape to the enzymes active site
-when the substrate is near the enzymes active site, the enzyme changes the shape of the active site to ensure there is a tight fit between the enzyme and substrate. this forms an enzyme substrate complex
-reaction occurs forming an enzyme product complex
-product is released from the enzymes active site
induced fit simple terms equation
enzyme + substrate —> ES complex—> EP complex —> enzyme + product
how does heat affect molecules
makes them vibrate
what is the temperature co-efficient Q10
Q10 value for a reaction shows how much the rate of reaction changes when the temperature is raised by 10°C
equation for Q10
Q10 = rate at higher temp/ rate at lower temp
what is a biological catalyst
speeds up metabolic reactions in living organisms which do not get used up in reaction
why is the tertiary structure of the active site crucial
as it’s shape is complementary to the shape of the substrate
what’s an example of an intracellulaire enzyme
catalase
what does catalase do
-breaks down hydrogen peroxide into H2O and O2
-consists of four polypeptide chains
-has a haem group (Fe+)
-found in vesicles called peroxsomes
-helps kill invading microbes when white blood cell ingests pathogen
what is an example of extra cellular enzyme
amylase
what does amylase do
-break down of starch into maltose
what is a buffer
used to maintain a desired pH
what’s an example of a buffer
-haemoglobin in the blood by donating or accepting pronouns
how does pH affect the binding of a substrate to the active site of an enzyme
hydrogen bonds and ionic forces between amino acids hold the tertiary structure of an enzyme molecule in the correct shape. Excess hydrogen ions will interfere with these H bonds and ionic forces so active site will change shape
how does substrate concentration affect rate of reaction
as substrate concentration increases so does rate of reaction- more collisions so more enzyme substrates
how does enzyme concentration affect rate of reaction
as enzyme concentration increases so does rate of reaction
what happens when rate of reaction slows down
(substrate concentration)
substrate concentration increases but all of the actual sites are occupied so increasing substrate concentration will have no effect
what happens when rate of reaction slows down
(concentration of enzyme)
substrate concentration is fixed so increased enzyme concentration will have no effect
what do enzymes do to the activation energy
lower it
how does temp effect enzyme reactions
-low temp enzymes have low kinetic energy. less likely to successfully collide with substrate so less enzyme substrate formed
-increase in temp: enzymes have more kinetic energy so more successful collisions and more enzyme substrate complexes
-above optimum temperature enzyme denature. bonds disrupted in enzyme so active site changes shape
-substrate can no longer bind so reaction stops
how does pH effect enzyme reactions
-each enzyme has an optimum pH, above or below this the enzymes denature
other factors affecting enzymes
-high substrate concentration chases faster rate, until they are used up
-high enzyme concentration causes faster rate again until they are used up
what is competitive inhibition
-inhibitor is similar or same shape to substrate
-inhibitor fits into active site of enzyme
-substrate therefore cannot enter
-amount of inhibition depends on relative concentration of substrate and inhibitor of molecules
-form enzyme inhibitor complex
-reduces number of free enzymes available to bind with substrate
-if inhibitor binds irreversibly to active site it is called an inactivator
what is non-competitive inhibition
-do not compete with substrate molecules for the active site
-inhibitors attach to an allosteric site away from the active site
-disruption of tertiary structure
-shape of enzyme active site changes
-enzyme is no longer complementary to substrate
what kind of structure is an enzyme
tertiary structure
what is an enzyme substrate complex
the structure of when the substrate binds to the active site
what type of protein is an enzyme
globular protein
what is an example of intra cellular enzyme
amylase
