RNA, Transcription, and Translation

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

Questions 1 - 10
1

Researchers first identified parts of genes that are spliced out of mRNA and not included in the final protein product by observing that not all of the original gene hybridizes to the cognate mRNA. What are these regions called?

Introns

Exons

Internal transcribed spacers

Inter genic regions

Micro RNAs

Explanation

Introns are regions included in genes that are not actually part of the final protein generated. Scientists first observed that some areas of genes are removed before mRNA translation by visualizing that not all of a gene hybridizes with its cognate mRNA, and hence there are pieces that are spliced out and not used. Note that splicing of introns, like all other post-transational modifications, only occurs in eukaryotes. The function of intron regions is thought to be mostly regulatory.

2

Researchers first identified parts of genes that are spliced out of mRNA and not included in the final protein product by observing that not all of the original gene hybridizes to the cognate mRNA. What are these regions called?

Introns

Exons

Internal transcribed spacers

Inter genic regions

Micro RNAs

Explanation

Introns are regions included in genes that are not actually part of the final protein generated. Scientists first observed that some areas of genes are removed before mRNA translation by visualizing that not all of a gene hybridizes with its cognate mRNA, and hence there are pieces that are spliced out and not used. Note that splicing of introns, like all other post-transational modifications, only occurs in eukaryotes. The function of intron regions is thought to be mostly regulatory.

3

Researchers first identified parts of genes that are spliced out of mRNA and not included in the final protein product by observing that not all of the original gene hybridizes to the cognate mRNA. What are these regions called?

Introns

Exons

Internal transcribed spacers

Inter genic regions

Micro RNAs

Explanation

Introns are regions included in genes that are not actually part of the final protein generated. Scientists first observed that some areas of genes are removed before mRNA translation by visualizing that not all of a gene hybridizes with its cognate mRNA, and hence there are pieces that are spliced out and not used. Note that splicing of introns, like all other post-transational modifications, only occurs in eukaryotes. The function of intron regions is thought to be mostly regulatory.

4

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

RNA polymerase I

RNA polymerase II

RNA polymerase III

DNA polymerase IV

DNA polymerase V

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.

5

What approximate percentage of total RNA content in a cell is messenger RNA (mRNA)?

Explanation

Only 2-5% of the total RNA content in a cell is mRNA. Approximately 10% is transfer RNA (tRNA), and approximately 85% is ribosomal RNA (rRNA).

6

What approximate percentage of total RNA content in a cell is messenger RNA (mRNA)?

Explanation

Only 2-5% of the total RNA content in a cell is mRNA. Approximately 10% is transfer RNA (tRNA), and approximately 85% is ribosomal RNA (rRNA).

7

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

RNA polymerase I

RNA polymerase II

RNA polymerase III

DNA polymerase IV

DNA polymerase V

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.

8

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

RNA polymerase I

RNA polymerase II

RNA polymerase III

DNA polymerase IV

DNA polymerase V

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.

9

What approximate percentage of total RNA content in a cell is messenger RNA (mRNA)?

Explanation

Only 2-5% of the total RNA content in a cell is mRNA. Approximately 10% is transfer RNA (tRNA), and approximately 85% is ribosomal RNA (rRNA).

10

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

All of these

A basal promoter (TATA box)

Enhancers that accept binding agents

Transcription factors

None 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.

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