Enzymes - Interference and Metabolism Flashcards
what makes many substances poisonous
they inhibit enzymes
what are metabolic poisons
interfere with metabolic reactions causing damage, illness or death
give three examples of metabolic poisons
- cyanide
- malonate
- arsenic
what is cyanide
non-competitive inhibitor of cytochrome c oxidase (catalyses respiration reactions)
what is malonate
competitive inhibitor of succinate dehydrogenase (catalyses respiration reactions)
what is arsenic
non-competitive inhibitor of pyruvate dehydrogenase (catalyses respiration reactions)
what is venom
a mixture of toxins and different enzymes
give examples of the enzymes/toxins in venom
- phosphodiesterases
- inhibitor of acetylcholinesterase
- ATPases
what is the effect of phosphodiesterases
interfere with heart, causing a drop in blood pressure
what is the effect of inhibitor of acetylcholinesterase
involved with nerve transmission and inhibition causes paralysis
what is the effect of ATPases
break down ATP - disrupts prey’s use of energy
what are metabolic pathways
the product of one enzyme controlled reaction is the substrate for the next one. they increase the efficiency of metabolic reactions
what needs to be controlled in metabolic pathways and how
- the buildup of end product needs to be controlled
- a process of end-product inhibition often occurs (feedback inhibition)
describe end-product inhibition
the end product binds to an enzyme earlier in the sequence
- this changes the active site shape, reducing the rate of reaction (reversible, non-competitive inhibition)
- less product is made
describe enzyme activation
- some enzymes are synthesised in an inactive precursor form
- before they can carry out their function, the protein has to be altered so that the active site assumes the correct shape or is exposed
give examples of how enzyme activation can occur
- adding a phosphate
- removing some of their amino acids
- adding a cofactor
which enzymes are synthesised in an inactive precursor form and why
many digestive enzymes are produced in this way so that while in cells they do not digest any of the cell’s molecules
give examples of enzymes which need to be activated
- trypsin
- pepsin
how is trypsin produced and altered
produced in the inactive form trypsinogen and, after a portion of its molecules is removed by another enzyme, it becomes active again as trypsin
how is pepsin produced and altered
secreted as inactive pepsinogen and this is converted to active pepsin by the action of HCl in the stomach
give an example of an enzyme thought to be vital for life
ATP synthase
why may enzymes not work properly
because they aren’t made correctly - there is either an error in translation/translation or the DNA code for the protein is damaged
