enzymes Flashcards
what is an enzyme
a protein that acts as a catalyst, increasing rate of reaction by reducing the amount of activation energy needed
why is the tertiary structure of an enzyme important
the active site has a specific tertiary structure which is complementary to a specific substrate, enabling an enzyme-substrate complex
what is an active site
in an enzyme, the group of amino acids that make up the region where a substrate fits to catalyse a reaction
what are anabolic enzymes
enzymes that build up, put together substrates
what are catabolic enzymes
enzymes that break down substrates into two products
how do enzymes increase rate of reaction
by lowering activation energy
what is the lock and key hypothesis
that the active site is specific to a substrate, when the substrate is bonded to the enzyme, an enzyme-substrate complex is formed
what do the r groups in the active site do
interact with the substrate and form temporary bonds, which puts strain on the bonds within the substrate which helps the reaction along, lowering activation energy
what is the induced-fit hypothesis
that the enzyme changes shape as the substrate enters, the initial interaction between the enzyme and substrate is relatively weak, but these weak interactions rapidly induce changes in the enzymes tertiary that strengthen binding putting strain on the substrate, lowering activation energy
name an example of an intracellular enzyme reaction
catalase catalyzes the conversion of hydrogen peroxide into water and oxygen
name an example of an extracellular enzyme reaction
amylase produced by the salivary glands breaks down starch into maltose
how does temperature affect enzyme activity
increases activity by increasing KE of the molecules increasing collision rate meaning there are more opportunities for reactions to occur, although if raised too much enzymes can denature
how do enzymes adapt to colder temperatures
more flexible structures, especially in the active site, but this makes them unstable so even small changes in temperature can denature them
how are enzymes in hot temperatures adapted
more stable, due to having more bonds, particularly hydrogen bonds and sulfur bridges in the tertiary structure
why are enzymes affected by pH
because proteins are affected by pH
do enzymes denature if the pH is changed slightly
no, their active site is only altered and can return to its normal shape if the pH is lowered - renaturation
do enzymes denature if the pH is too extreme
yes
what is a competitive inhibitor
has a similar shape to a substrate so can fit in the active site, this prevent the actual substrate being in the active site
what is an example of a competitive inhibitor
aspirin and statin
what is a non-competitive inhibitor
binds to the allosteric site of an enzyme, this causes the tertiary structure to change making the active site change shape,
what is end product inhibition
when the product of a reaction acts as an inhibitor to the enzyme that produced it, negative feedback, this so excess products arent made and resources arent wasted
what is an example of a metabolic pathway
respiration
what is a cofactor
some enzymes need a non protein helper to carry out their function as a biological catalyst
what is a coenzyme
when the cofactor is an organic molecule
what are prosthetic groups
cofactors that are tightly bound or permanently attached to the enzyme
what are precursor enzymes
enzymes that are inactive when produced because they could cause damage to the cells that they are produced in
how are precursor enzymes activated
cofactors, another enzyme, change in conditions such as temperature or pH
what are precursor enzymes called before and after a cofactor is added
apoenzyme and holoenzyme
what are proenzymes/zymogens
precursor enzymes that need a biochemical change to be activated
give an example of a cofactor
chloride ions are a cofactor for amylase
