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Biology - 2.4 Enzymes > Inhibitors > Flashcards

Flashcards in Inhibitors Deck (16)
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what are competitive inhibitors

>competetive inhibitors molecules have a similar shape to the of substrate molecules
> They compete with the substrate molecules to bind to the active site, but no reaction takes place
> Instead they block the active site, so no substrate molecules can fit in it


How does higher conc of substrate affect an competitive inhibitor?

> The chances of substrate getting to an active site before an inhibitor increase
> so increasing conc of substrate will increase the rate of reaction


How does higher conc of an competitive inhibitor affect an enzyme?

it will take up nearly all of the active sites and hardly any of the substrate will get to the enzyme


What are non competitive inhibitors?

> Non competitive inhibitors molecules bind to the enzyme away from its active site
> the site they bind to is known as the enzyme's allosteric site
> This causes the active site to change shape so the substrate molecules can no longer bind to it.


Why do non competitive inhibitors don't compete with the substrate molecules to bind?

Because they are a different shape


How does increasing conc affect a non competitive inhibitors?

increasing conc will make no differnce because they don't bind to the active site as they have a different shape


how do irreversible inhibitor bind?

they bind permanently to an enzyme as they have strong covalent bonds


how do reversible inhibitor bind?

they don't bind permanently to an enzyme as they have weak hydrogen bombs or weak ionic bonds


How does an antiviral drug inhibitor work?

e.g. reverse transcriptase inhibition treat HIV. They work by inhibiting the enzyme reverse transcriptase, which catalyse the replication of viral DNA. This prevents the virus from replicating.


How does antibiotic inhibitor work?

e.g. pencilin inhibits the enzyme transeptidase, which catalyses the formation of protein in cell walls. This weakens the cell wall and prevent the bacterium from regulating its osmotic pressure. As a results the cell bursts and the bacterium is killed.


What is cyanide (metabolic poisons)

> its a non competitive, irreversible inhibitor of cytochrome
C oxidase
> it catalyses respiration reactions


What is Maltonate (metabolic poisons)

> its a competitive inhibitor of succinate dehydrogenase
> catalyses respiration reactions


What is Arsenic (metabolic poisons)

> its a non competitive inhibitor of peruse dehydrogenase
> catalyses respiration reactions


What is product inhibition?

its when a product inhibits the enzyme that has catalysed its formation


what is end product inhibition?

its when the final product in a metabolic pathway inhibits an enzyme that acts earlier in the pathway


describe enzyme as inactive precursors

Enzymes are sometimes synthesised as inactive precursors in metabolic pathway to prevent them causing damage to cells. Part of the precursors molecule inhibits its action as an enzyme. Once this part is removed the enzyme becomes active