Biology Biomolecules MDCAT 2017
PMDC Verified Question 133 of 142
The number of amino acids that have been found to occur in cells and tissues are:
A
25
B
20
C
45
D
170
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: 170
Concept:

There is a vast difference between the total amino acids found in nature versus the specific few encoded by DNA to build proteins.

Solution:

  • Biochemists have identified approximately 170 different types of amino acids scattered throughout various cells and tissues in nature.


  • Many of these serve independent metabolic functions (e.g., ornithine, citrulline) and are never incorporated into proteins.


Why other options are incorrect:

  • 20-25: This refers strictly to the "standard" proteinogenic amino acids that are used specifically as building blocks to synthesize cellular proteins, not the total number found in biological tissues.

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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