Question 21N.2.SL.TZ0.8a
| Date | November 2021 | Marks available | [Maximum mark: 4] | Reference code | 21N.2.SL.TZ0.8a |
| Level | SL | Paper | 2 | Time zone | TZ0 |
| Command term | Outline | Question number | a | Adapted from | N/A |
Outline the process of protein denaturation.
[4]
a. change to conformation/shape/tertiary structure/3-D shape;
b. bonds within the protein/intramolecular bonds broken/changed;
c. pH and temperature (outside tolerated ranges) can cause denaturation;
d. vibrations/heat at high temperatures breaks bonds;
e. high pH/low pH/extreme pH alters ionization/charges (of amino acids and breaks ionic bonds);
f. protein cannot carry out its function
OR
active site of enzymes cannot bind substrates/catalyze reaction/no enzyme-substate complex;
g. permanent/irreversible change (usually)
OR
soluble proteins become insoluble/precipitate;
Allow any mark points if made clearly on an annotated graph or diagram.
Most candidates knew that denaturation can be caused by excessive temperatures or extreme pH. Fewer candidates mentioned how bonds within a protein are broken by heat or kinetic energy. Even fewer explained how R-group ionization in acidic and basic amino acids can be altered by pH changes, breaking the ionic bonds within protein molecules that help to stabilize tertiary structure.
