NBME 20 Answers : Block 3 : #19 = A 23-year-old man comes to the physician because of ...

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NBME 20 Answers

nbme20/Block 3/Question#19

A 23-year-old man comes to the physician because of ...

Area labeled ‘B’ (Mitochondrion)

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submitted by jinzo(5),

A - nucleus ( with nucleolus inside ) B - mitochondria C - RER ( you can see attached ribosomes ) D - ?? may be lysosomes E - glycogen granules

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submitted by qfever(8),

Does anyone know what are A, C, D? For C not sure if it's pointing to the ribosomes on RER.

(I'm assuming E is glycogen granules based on a comment below!)

drdoom see @jinzo’s comment above +

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submitted by usmle11a(26),

https://www.youtube.com/watch?v=k0YqEpA-62A

guys this video explains alot

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submitted by usmile1(29),

does anyone know what the structure E is pointing to?

thomasburton Not sure looks like it might be free ribosomes or other such small cytosolic structure (I picked E too, thought B looked way too big!) +

targetusmle same here!! marked e thinking of it as a mitochondria +1

msyrett Glycogen Granules! They are not membrane bound and float freely in the cytoplasm. +1

+0 upvote downvote
submitted by lianallado(1),

This patient presents with a mitochondrial myopathy since the disorder is inherited from the mother. Mitochondrial myopathies show “ragged red fibers” on muscle biopsy due to the accumulation of diseased mitochondria in the subsarcolemma of the muscle fiber.

katsu Mitochondrial myopathies—rare disorders; often present with myopathy, lactic acidosis, and CNS disease, eg, MELAS syndrome (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes). 2° to failure in oxidative phosphorylation. Muscle biopsy often shows “ragged red fibers” (due to accumulation of diseased mitochondria). +