Heavy metal ions such as mercury and lead are poisonous partly because they
Correct answer: D. bind to sulphur containing groups in enzymes and denature them irreversibly
- A. increase enzyme activity uncontrollably
- B. are converted into proteins by the body
- C. supply too much energy to the cell
- D. bind to sulphur containing groups in enzymes and denature them irreversibly
Explanation
These ions attack the sulphydryl side chains of cysteine, breaking disulphide bridges and destroying the tertiary structure, so the affected enzymes lose all activity permanently. Because the damage cannot be reversed by removing the metal, the effect is poisoning rather than simple inhibition. This is also why drinking milk or egg white gives some first aid benefit, as those proteins bind the metal first.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? support@testustad.com
About Enzymes as Biocatalysts
Enzymes are protein or RNA biocatalysts that lower activation energy without being consumed, and their active sites bind specific substrates. The topic covers the lock and key and induced fit models, effects of temperature, pH and substrate concentration, cofactors, enzyme specificity, and competitive versus non-competitive inhibition.
Practise Macromolecules
299 free Macromolecules MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Chemistry questions like this
Chemistry is on 14 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Enzymes as Biocatalysts questions
A competitive inhibitor reduces the rate of an enzyme catalysed reaction by
Enzyme activity is lost above about 45 degrees Celsius because
The high specificity of an enzyme for its substrate is due to
Each enzyme works fastest at a particular pH because a change in pH
An enzyme lowers the activation energy of a reaction by
Compared with an inorganic catalyst such as manganese dioxide, an enzyme is