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MDCAT
Chemistry
2021

Chemistry · Macromolecules

Work through this past-paper style MCQ, then read the full explanation. Practice more chemistry questions on mMCQ with adaptive practice and topic analytics.

Question

Which of the following element is not present in all proteins ?

Options
  • A

    S

  • B

    C

  • C

    N

  • D

    O

Explanation

Option A is correct since sulfur is present only in some proteins, not all.

The general formula for proteins is RCH(NH2)COOH implying that ALL the proteins at least contain C, H, N and O 

A is correct since sulphur is present only in some proteins, not all. The general formula for proteins is RCH(NH2)COOH implying that ALL the proteins at least contain C, H, N and O

(C) Carbon – Incorrect: Carbon is a fundamental element in all organic molecules, including proteins. It forms the backbone of amino acids and peptide bonds.

(N) Nitrogen – Incorrect: All proteins contain nitrogen because amino acids, the building blocks of proteins, have an amino group (-NH₂) that contains nitrogen.

(O) Oxygen – Incorrect: Oxygen is present in all proteins as part of the carboxyl (-COOH) and amide (-CONH₂) groups in amino acids.

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Tagged under Chemistry · Macromolecules · 2021