Enzymes PPQ corrections

Explain shape of curve between 30 and 50 (rate decreasing)

Enzyme denaturing
Bonds holding tertiary structure are broken/ tertiary structure disrupted
Change in shape of active site
Fewer/ no ESC can form

Describe induced-fit model

Before reaction, active site is not complementary to substrate
Shape of active site changes as enzyme-substrate forms
Pressure on bonds in substrate
Lowers activation energy

Describe how to produce calibration curve

Make maltose solutions of different known concentrations
Carry out qualitative Benedict’s test on each
Use colorimeter to measure absorbance of each solution and plot calibration curve
Find concentration of sample from calibration curve

Describe + explain differences between two graphs (curve>plateau vs straight diagonal)

Start of graph
Higher rate at 37
due to more KE so moving faster, more frequent successful collisions
more ESC forming
Rest of graph
At 37, plateaued
all substrate used up
At 25 rate remains constant as conc. of product continuing to increase as not all substrate has been used up

Difference in rates of reaction at 60 and 37 degrees between 20 and 40 mins

Different times -
Higher temp of 60 degrees causes denaturation of all enzymes
Reaction stops sooner because no more ESC can form
whereas at 37 degrees, reaction still occurring
Different conc. of product -
At 60 degree graph, substrate still available when enzyme denatured
but not converted into product (so lower conc. of product)

Explain shape of curves at 50 and 60

Both denatured by high temps
Denatured faster at 60 degrees due to more KE
Hydrogen and ionic bonds break between R groups
Change in shape of active site, ESC can’t form