enzymes

what is the definition of an enzyme

biological catalysts that speed up the rate of a reaction without being used up itself, therefore they can be used up over and over again even in small quantities, they are also proteins and synthesised by ribosomes

what is the structure of an enzyme

3D structure, containing an active site

what are substrates

molecules that bind to the active site, the structure is called an enzyme substrate complex

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describe it

what is the relationship between enzymes and temperature

for an enzyme to work correctly, it must collide with the substrate. as temperature increases, so does kinetic energy causing the likelihood of a successful collision between enzyme and a substrate, enzymes work fastest at their optimum temperature (in the human body around 37 degrees celcius)

what is denaturation

at higher temperatures, enzymes can denature and bonds inside the site rupture. when enzymes denature, the rate of reaction decreases significantly because the active site and substrate are no longer complementary with each other

describe a practical involving temperature and enzymes

1. heat a solution containing starch to a spotting tile

2. add iodine to the wells (positive colour change orange → blue/black)

3. add amylase to the wells

   the amylase will break down the starch slowly at low temperature

   the amylase will break down the starch quickly at optimum temperature

   at high temperatures the enzyme will denature and stop working

describe the relationship between enzymes and pH

• pH is a measure of how acidic or alkaline a solution is

• each enzyme has a different optimum pH

  most work well with a neutral pH (pH7)

• if the pH is too far from the optimum the enzyme may denature, as it ruptures the bonds in the active site