Biology Biomolecules ETEA 2023
PMDC Verified Question 59 of 142
Amino acids mainly differ from each other by the difference in their:
A
Amino group
B
Carboxyl group
C
Hydrogen alpha carbon
D
R-group
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: R-group
Concept:

All amino acids share a universal backbone, yet 20 vastly different types exist to build complex proteins.

Solution:

  • Every single amino acid possesses the exact same structural backbone: a central alpha carbon bonded to an amino group, a carboxyl group, and a solitary hydrogen atom.


  • The only structural component that varies from one amino acid to the next is the fourth bond: the highly variable side chain, universally termed the R-group.


  • It is this specific R-group that dictates whether an amino acid is acidic, basic, polar, or non-polar.


Why other options are incorrect:

  • Amino, Carboxyl, and Hydrogen: These three groups are absolutely identical across all 20 standard amino acids; they do not differ.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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