GRE Subject Test: Biology : Understanding the Nucleus

Study concepts, example questions & explanations for GRE Subject Test: Biology

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Example Questions

Example Question #1 : Understanding The Nucleus

How are proteins imported into the nucleus?

Possible Answers:

Proteins are only exported from the nucleus

With the assistance of special proteins known as importins 

Passive diffusion through nuclear pore complexes

Translocation through nuclear pore complexes while they are being translated by membrane-bound ribosomes

Correct answer:

With the assistance of special proteins known as importins 

Explanation:

Nuclear import and export is tightly regulated by importin and exportin proteins. These proteins interact with target proteins to carry them into or out of the nucleus, respectively. Proteins cannot passively diffuse into the nucleus and they are not translocated into the nucleus during translation.

Example Question #2 : Other Organelles

Which of the following is true regarding the nucleus?

Possible Answers:

All of these answers

The nucleus is studded with many openings called nuclear pore complexes

The nucleus is surrounded by multiple membranes

The nucleus is the site of assembly for ribosomal subunits

Correct answer:

All of these answers

Explanation:

All of these choices are correct regarding the nucleus. Nuclear pore complexes are incredibly important for regulating nuclear import and export. Ribosomal subunits are assembled in the nucleolus, which is a portion of the nucleus. The nucleus is covered by two lipid bilayers, which constitute the nuclear envelope.

Example Question #2 : Understanding The Nucleus

What provides structural support for the nucleus and binds chromatin?

Possible Answers:

Cytoskeleton

Nucleolus

Lamina 

Nuclear pores

Nuclear envelope

Correct answer:

Lamina 

Explanation:

The correct answer is lamina. This is a fibrous network of filaments within the nucleus that provides architectual support similar to the cytoskeleton. Chromatin also is held in place by association with the lamina. 

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