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

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

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Example Questions

Example Question #11 : Rna, Transcription, And Translation

What event is indicative of transcription initiation?

Possible Answers:

RNA polymerase binds to the promoter

Telomerase lengthens the telomeres of the DNA

The RNA strand begins to be synthesized

RNA polymerase is removed from the DNA

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

Enhancers

Exons

Introns

Transcriptional start sites

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 #11 : Transcription And Rna

When does alternative splicing occur? 

Possible Answers:

Following pre-mRNA transcription in the nucleus

Following mRNA loading into ribosome

Following translation

Following mRNA polyadenylation 

Following mRNA translocation to the cytosol 

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 #12 : Transcription And Rna

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

Possible Answers:

Transcription factors

Enhancers that accept binding agents

All of these

A basal promoter (TATA box)

None of these

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 #13 : Transcription And Rna

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

Possible Answers:

The base sequence of the enhancer

The location of the AUG start codon

The base sequence of the promoter

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 #14 : Transcription And Rna

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

Possible Answers:

Capping of the 5' end

Nucleotide excision repair

Polyadenylation of the 3' 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 #15 : Transcription And Rna

What are exons?

Possible Answers:

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

Site where repressor proteins bind

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.

Example Question #16 : Transcription And Rna

What are snRNPs (small nuclear ribonucleic particles)?

Possible Answers:

RNA molecules that serve as the link between the nucleotide sequence of nucleic acids and the amino acid sequence of proteins

RNA protein complexes that combine with pre-mRNA and other proteins to form a spliceosome

RNA component of the ribosome, essential for protein synthesis

RNA molecules that convey genetic information from DNA to the ribosome

Correct answer:

RNA protein complexes that combine with pre-mRNA and other proteins to form a spliceosome

Explanation:

snRNPs are RNA protein complexes that combine with pre-mRNA and other proteins to form a spliceosome. Spliceosomes remove introns from pre-mRNA. After final modifications, the spliced pre-mRNA is considered mature mRNA and can be exported to the cytoplasm for translation.

mRNA is an RNA molecule that conveys genetic material from DNA to the ribosome. tRNA is an RNA molecule that serves as the link between the nucleotide sequence of nucleic acids and the amino acid sequence of proteins. rRNA is the RNA component of the ribosome that is essential for protein synthesis in all living organisms.

Example Question #17 : Transcription And Rna

Which of the following is not a type of RNA?

Possible Answers:

cRNA

tRNA

mRNA

rRNA

Correct answer:

cRNA

Explanation:

mRNA, tRNA, and rRNA are the most commonly recognized types of RNA, though there are several more divisions. Messenger RNA (mRNA) is the product of gene transcription and is used to carry genetic information to ribosomes for translation. Transfer RNA (tRNA) is used to transport amino acid residues to active ribosomes during translation and contains anticodon sequences to bind to mRNA. Ribosomal RNA (rRNA) forms part of the ribosomes structure.

Though cRNA is not a class of RNA molecule, complementary DNA (cDNA) is used to store and analyze genomes. cDNA is the non-coding complement to the template strand used for transcription, and can be used to analyze genetic sequences.

Example Question #5 : Help With Rna Structure And Modification

All of the follwing are types of alternative RNA splicing except __________.

Possible Answers:

skipped exon

alternative 3' splicing

dual splice site

exon reversal

Correct answer:

exon reversal

Explanation:

Skipped exon, dual splice site, and alternative 3' splicing are all types of alternative RNA splicing. Exon reversal is a nonsense term, and does not represent an actual biochemical process.

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