GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with Protein Transport

Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology

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Example Questions

Example Question #1 : Help With Protein Transport

Which of the following does not require a post-translational modification of a protein to be properly targeted to its destination?

I. Nuclear localization

II. Targeting proteins to the lysosome

III. Targeting proteins to the proteasome

IV. Nuclear export

Possible Answers:

I, II, and IV

II and III

I only

I and IV

Correct answer:

I and IV

Explanation:

Nuclear import and export do not require post-translational modifications. The nuclear localization sequence or the nuclear export sequence is contained within the amino acid sequence itself (primary structure), and does not require and special modification.

For targeting to the proteasome, proteins must be ubiquinated. To target a protein to the lysosome the addition of a mannose-6-phosphate is commonly made. 

Example Question #1 : Help With Protein Transport

Which of the following organelles would be least important in a cell that creates and secretes proteins?

Possible Answers:

Ribosomes

Smooth endoplasmic reticulum

Golgi apparatus

Rough endoplasmic reticulum

Correct answer:

Smooth endoplasmic reticulum

Explanation:

When considering a protein creating/secreting cell, the organelles that are responsible for packaging and secreting the proteins will be most important. Starting at the beginning, proteins will be translated using the ribosomes found on the rough endoplasmic reticulum. Those will then be sent to the golgi apparatus for proper packaging. Those packages will then be released from the cell. The smooth endoplasmic reticulum will not be a vital organelle for protein creation and secretion.

All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources

1 Diagnostic Test 201 Practice Tests Question of the Day Flashcards Learn by Concept
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