GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with Nuclear Structure

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 Nuclear Structure

What is the main function of the nucleolus in eukaryotic cells?

Possible Answers:

Storage site for transcription factors, RNA polymerases, DNA polymerases, and other transcriptional machinery until transcription occurs

To promote the transcription, processing, and assembly of rRNA genes into ribosomes

The site of microtubule assembly during mitosis

To facilitate nuclear transport of proteins and mRNA from the nucleus to the cytoplasm

Eukaryotic cells do not have a nucleolus

Correct answer:

To promote the transcription, processing, and assembly of rRNA genes into ribosomes

Explanation:

The correct answer is that the nucleolus is the site of ribsome synthesis and assembly. Chromosomes containing rRNA (ribosomal RNA genes) are clustered within the nucleolus, which facilitates rapid transcription and processing of rRNA genes and assembly of rRNA subunits into ribosomes. 

Example Question #2 : Help With Nuclear Structure

The nuclear lamina is generally associated with __________.

Possible Answers:

heterochromatin and transcriptionally active genes

euchromatin and transcriptionally inactive genes

chromatin containing transcriptionally active genes

chromatin containing transcriptionally inactive genes

ribosome synthesis and assembly 

Correct answer:

chromatin containing transcriptionally inactive genes

Explanation:

The correct answer is chromatin and transcriptionally inactive genes. The nuclear lamina provides support and structure to the nucleus and binds transcriptionally inactive regions. Euchromatin is loosely packed chromatin and is, therefore, associated with transcriptionally active genes. Alternatively, heterochromatin is densely packed chromatin and implies inactive genes. Ribosome synthesis and assembly occurs in the nucleolus.

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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