Enzyme reactions

independent variables to change when doing enzyme investigations

pH

temperature

concentration of substrate

concentration of enzyme

dependent variables in enzyme investigations

time

volume

mass

absorbance

from a graph what are three different rates that can be calculated

rate between two line

initial rate- instant that the substrate and enzymes are mixed

rate at a particular time

how to work out the rate

change in y axis value divided by change in x axis value

how to explain low pH in a graph

in low pH there is a high concentration of H+ ions

more amino groups will have a positive charge so will affect hydrogen and ionic bonding in the protein

this will change the 3D shape of the active site

as the pH becomes more acidic fewer bonds can form between the active site and the substrate molecules

fewer enzyme-substrate complexes form and the rate decreases.

how ton explain high pH in a graph

not enough H+ ions are present

increasing number of carboxylic acid groups have negative charge

hydrogen anionic bonding are effected and the 3D shape of the active site changes making it less able to from bonds within the substrate.

what happens at A (3)

at low substrate concentration, the number of substrate molecules is low and not all the active sites of the enzyme molecules are occupied

as the concentration of the substrate increases, there is a greater frequency of enzyme- substrate complex formation and an increase in rate of reaction.

at low substrate concentrations the number of molecules of substrate acts as the limiting factor.

what happens at B (3)

at higher substrate concentrations more of the active sites are occupied at the same time

frequency of enzyme-substrate complex formation increases at a slower rate.

smaller increase in rate of reaction

what happens at C (4)

because there are a fixed number of active sites eventually you reach a maximum rate of reaction

all the active sites are occupied- SATURATED

adding more substrate cannot cause an increase in the rate of reaction as no more active sites are available

at high substrate concentrations the number of molecules of enzyme acts as a limiting factor

what happens at A (4)

at low enzyme concentrations the number of enzyme molecules is low and all active sites the enzyme molecules are occupied

as the concentration of enzymes increases more active sites are available

there is a greater frequency of enzyme-substrate complex formation and an increase in the rate of reaction

at low enzyme concentrations the number of molecules of enzyme acts as a limiting factor

what happens at B (4)

at higher enzyme concentrations, more active sites become available

substrate concentration is limited

the frequency of enzyme-substrate complex formation increases at a slower rate

smaller increase in rate of reaction

what happens at C (4)

because there are a fixed number of substrate molecules eventually you reach a maximum rate of reaction

adding more enzyme substrate cannot cause an increase in rate of reaction as no more substrate molecules are available

at high enzyme concentrations, the number of molecules of substrate acts as a limiting factor

only adding more substrate can the maximum be increased