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

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

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

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

Example Questions

Example Question #1 : Rna, Transcription, And Translation

Which polymerase is involved in transcribing ribosomal RNA (except 5S rRNA)?

Possible Answers:

RNA polymerase III

DNA polymerase IV

DNA polymerase V 

RNA polymerase II

RNA polymerase I

Correct answer:

RNA polymerase I

Explanation:

The correct answer is RNA polymerase I. The sole purpose of RNA polymerase I in eukaryotes is to transcribe ribosomal RNA, with the exception of 5S rRNA, which is transcribed by RNA polymerase III. RNA polymerase III also transcribes tRNAs and other small RNAs. Transcripts of RNA polymerase II are 5' capped, polyadenylated, and spliced to ultimately be translated into functional protein. DNA polymerase IV/V are polymerases involved in DNA replication and repair. 

Example Question #1 : Help With Transcription Processes

What is the role of the promoter region in the regulation of gene expression?

Possible Answers:

Allow for alternative splicing and recombination of genetic components

Bind negative regulators to inhibit gene expression

Recruit RNA polymerase and transcription factors to DNA

Alter gene expression by binding transcription factors

Correct answer:

Recruit RNA polymerase and transcription factors to DNA

Explanation:

The promoter region is the site of a gene where RNA polymerase and other transcription factors bind to DNA, upstream from the gene locus. A mutation in this region commonly results in a decrease in the amount of gene transcribed.

An enhancer region is a stretch of DNA that alters gene expression by binding transcription factors, while a silencer region is a site on the gene where repressor proteins bind. Introns are intervening non-coding segments of DNA that are not expressed in the final protein. Alternative splicing patterns of introns and exons allows for multiple proteins to be generated from a single gene.

Example Question #2 : Rna, Transcription, And Translation

Which of the following are methods for termination of transcription in prokaryotes?

I. Release factor binding

II. Rho-mediated termination

III. Hairpin loop (stem loop) formation

Possible Answers:

I, II, and III

II and III

I only

III only

Correct answer:

II and III

Explanation:

The binding of release factors is a common way to terminate translation, not transcription.

Rho-mediated termination and hairpin loop formation are both common ways to terminate prokaryotic transcription. The formation of the hairpin loop disrupts the transcription machinery and the DNA-RNA interactions, which allows termination of transcription. Rho is a protein that is capable of binding single-stranded RNA and terminating transcription. 

Example Question #1 : Help With Transcription Processes

What event is indicative of transcription initiation?

Possible Answers:

Telomerase lengthens the telomeres of the DNA

RNA polymerase is removed from the DNA

The RNA strand begins to be synthesized

RNA polymerase binds to the promoter

Correct answer:

RNA polymerase binds to the promoter

Explanation:

During the initiation of transcription, RNA polymerase and a group of transcription factors bind to the promoter for a given gene. This DNA segment signals the RNA polymerase where to begin creating the RNA strand. 

Example Question #2 : Help With Transcription Processes

Which of the following best describes distant regulatory sequences that influence gene expression?

Possible Answers:

Promoters

Introns

Transcriptional start sites

Enhancers

Exons

Correct answer:

Enhancers

Explanation:

The correct answer is enhancer. Transcription factors and mediators bind enhancer regions of DNA and influence the transcription of distant genes by chromatin looping to the proximal promoter. Promoters are regulatory sequences, however, they are typically 2 kilobase pairs upstream of the gene for which they influence transcription. Introns and exons make up a gene and are the non-coding and coding regions of the gene, respectively. The transcriptional start site consists of the first few nucleotides that are transcribed into an mRNA sequence from a gene, usually containing the 5' untranslated region (UTR).  

Example Question #3 : Help With Transcription Processes

When does alternative splicing occur? 

Possible Answers:

Following mRNA polyadenylation 

Following translation

Following mRNA translocation to the cytosol 

Following mRNA loading into ribosome

Following pre-mRNA transcription in the nucleus

Correct answer:

Following pre-mRNA transcription in the nucleus

Explanation:

The correct answer is following pre-mRNA transcription in the nucleus. Pre-mRNA contains introns and exons. Following transcription, splicing and alternative splicing occurs to remove introns and select exons, respectively, by the spliceosome. Following splicing, 3' poly adenylation and 5' capping occur to generate a mature mRNA transcript that will translocate to the cytosol and be translated by ribosomes. 

Example Question #4 : Help With Transcription Processes

What element(s) do all eukaryotic promoter regions share?

Possible Answers:

None of these

A basal promoter (TATA box)

Transcription factors

All of these

Enhancers that accept binding agents

Correct answer:

All of these

Explanation:

Eukaryotic promoters share basic, highly conserved structure. This area does not evolve quickly because it is extremely important in DNA transcription. These promoters (in most cases) include a basic basal promoter like a TATA box, and enhancers that bind to transcription factors.

Example Question #95 : Molecular Biology And Genetics

During transcription of a eukaryotic cell, what determines the template strand?

Possible Answers:

The base sequence of the enhancer

The base sequence of the promoter

The location of the AUG start codon

The location of the MET start codon

The base sequence of the operator

Correct answer:

The base sequence of the promoter

Explanation:

The TATA box is found in the promoter region of the template strand. This TATA box serves as a signal for the initiation of translation of DNA into mRNA. The location of the promoter region and it's unique base sequence signals the start of the translation process.

Example Question #441 : Gre Subject Test: Biochemistry, Cell, And Molecular Biology

Which of the following processes is not a type of RNA processing carried out by eukaryotes?

Possible Answers:

Polyadenylation of the 3' end

Nucleotide excision repair

Capping of the 5' end

Splicing and removal of introns

Correct answer:

Nucleotide excision repair

Explanation:

Processing of pre-mRNA occurs in the nucleus. After transcription, three crucial modification take place. A 7-methylguanosine molecule is added to the 5' end to form a cap. Polyadenylation is added to the 3' end to create a poly-A tail. Introns are spliced out by spliceosomes, removing the non-coding regions of the RNA. The final product after modifications is considered a mature mRNA; prior to this, the transcript is known as heteronuclear RNA (htRNA).

Nucleotide excision repair is a method of proofreading after DNA replication to reduce the frequency of mutation.

Example Question #442 : Gre Subject Test: Biochemistry, Cell, And Molecular Biology

What are exons?

Possible Answers:

Site where repressor proteins bind

Set of genes that are adjacent to one another in the genome and are coordinately controlled

Genetic information coding for an amino acid sequence that will form a functional protein

Intervening non-coding segments of DNA

Correct answer:

Genetic information coding for an amino acid sequence that will form a functional protein

Explanation:

Exons contain the actual genetic information coding for protein. In contrast, introns are intervening non-coding segments of DNA. During the splicing process of pre-mRNA modification, introns are removed from the sequence. Alternative splicing patterns allow multiple exon sequences to be created from a single gene, resulting in multiple proteins.

An operon is a set of genes that are adjacent to one another in the genome and are coordinately controlled. The silencer region is a site of a gene where repressor proteins bind to regulate gene expression.

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

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