Cell Bio Passage

[premedrose]

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There are 2 groups of lysosomal storage diseases. In Group I, there are 2 diseases, Smith syndrome and Jones syndrome, each of which is lacking a different lysosomal hydrolase, resulting in accumulation of a glycosaminoglycan within lysosomes. There is an isolated cells from patients with Smith syndrome and patients with Jones syndrome. When cells from the 2 syndromes are fused, glycosaminoglycans are now degraded properly.

In addition, surprisingly, when the medium (supernatant = solution outside of the cells) from a culture of Smith cells (“donor”) is added to a culture of Jones cells (“recipient”), the Jones defect is corrected (Jones glycosaminoglycan is now degraded).


In Group II, there are 3 diseases, all due to a defect in the sorting of hydrolases from the Golgi to the lysosome: 2 are due to defects in the enzymatic processing of the mannose 6-phosphate marker on the
hydrolase (GlcNAc phosphotransferase and GlcNAc phosphoglycosidase, diagrammed below) and one is due to a mutation in the M6P receptor that targets the hydrolase to the lysosomal surface. Group II diseases result in functional hydrolases that are secreted from the cell rather than being transported to lysosomes.

Isolated cells (A, B, and C) from patients with each of the 3 specific Group II diseases.
Experiments with supernatants from these cell lines give the results below:
Result 1. The supernatant from normal cells corrects the defects in A and B but not the defect in C.
Result 2. The supernatant from C corrects the defect in cells from patients with Jones syndrome but the supernatants from A and B do not.
Result 3. If the supernatants from the mutant cells are first treated with an enzyme to remove GlcNAc, then the supernatants from C and B correct the defect in Jones cells, but the supernatant from A does not.

The figure is attached.



Defect in GlcNAc phosphotransferase come from which cell line?
A- A
B- B
C- C
D- none

Defect in GlcNAc phosphoglycosidase come from which cell line?
A- A
B- B
C- C
D- none

Defect in M6P receptor come from which cell line?
A- A
B- B
C- C
D- none

 

[RogueUnicorn]

why do you have two usernames
also, you already have a thread for this.

 

[unique135]

Where are you guys asking these questions from. Doesnt seem to be from any MCAT books.

 

[unique135]

why do you have two usernames
also, you already have a thread for this.

Agreed lol

 

[RogueUnicorn]

dude don't help people with their biochem hw

 

[unique135]

dude don't help people with their biochem hw

Erased it

 

[premedrose]

dude don't help people with their biochem hw

These are questions from the Molecular Biology of the Cell Problems book. I am studying from there since I heard that this book is the "bible of biology" I though it would help for the MCAT. First off I am done with biochem last year, and in upper level bio classes we don't get hw it is all based on exams.

 

[unique135]

These are questions from the Molecular Biology of the Cell Problems book. I am studying from there since I heard that this book is the "bible of biology" I though it would help for the MCAT. First off I am done with biochem last year, and in upper level bio classes we don't get hw it is all based on exams.

Hmm...It will give a strong background although not needed. MCAT may include such passage along with the information needed.

For now, think of the importance of M-6P, its receptor and their locations. This should help find you one answer. This passage has conceals or even misguides one essential information (somewhere in results) that answers other two questions.

Hope this helps

 

[SN2ed]

Closed thread: Unrelated to the MCAT