In eukaryotes, what does transcription produce?

Question

In eukaryotes, what does transcription produce??  
A. mRNA  
B. pre-mRNA  
C. rRNA  
D. tRNA

Accepted Answer

Correct Answer: (B)pre-mRNA. 
Rationale: In eukaryotes, transcription of protein-coding genes produces pre-mRNA.Transcription is the synthesis of an RNA molecule from a DNA template. In eukaryotes, this occurs within the nucleus. For genes that encode proteins, the immediate RNA product is not the mature messenger RNA (mRNA) that will be translated. Instead, it is a precursor molecule known as pre-messenger RNA (pre-mRNA). This primary transcript is an exact RNA copy of the gene, including both coding sequences (exons) and non-coding intervening sequences (introns). It also has unmodified ends. This pre-mRNA must undergo several processing steps in the nucleus before it becomes functional mRNA: addition of a 5' cap (a modified guanine nucleotide), addition of a 3' poly-A tail (a string of adenine nucleotides), and splicing to remove introns and join exons together. Only after this processing is the molecule considered mature mRNA, which is then exported to the cytoplasm for translation.A) mRNAMature mRNA is the final, processed form that is translated into protein. Transcription itself does not directly produce this mature form. The enzyme RNA polymerase synthesizes the primary transcript (pre-mRNA), and subsequent processing events convert it into mRNA. Therefore, while mRNA is the ultimate functional product of the transcription/processing pathway, it is not the direct product of the transcription event.B) pre-mRNAPre-mRNA is the direct, unprocessed RNA transcript synthesized by RNA polymerase II from protein-coding genes. It is chemically identical to the DNA template strand (with uracil replacing thymine) and contains all the intronic and exonic sequences. It is the raw material that the nuclear processing machinery acts upon. For most biology contexts focusing on gene expression, "transcription" refers to this initial synthesis, making pre-mRNA the correct answer.C) rRNARibosomal RNA (rRNA) is also a product of transcription, synthesized by RNA polymerase I (for the large rRNAs) and RNA polymerase III (for the 5S rRNA) from rRNA genes. The initial transcripts are pre-rRNA molecules that are then processed (cleaved and modified) to yield the mature rRNA components of the ribosome. While transcription does produce pre-rRNA, the question is typically interpreted in the context of the central dogma and protein synthesis, where the product of transcribing a protein-coding gene is of primary interest.D) tRNATransfer RNA (tRNA) is transcribed by RNA polymerase III from tRNA genes. The initial transcript is a pre-tRNA that undergoes processing (trimming, base modifications, and sometimes splicing) to become a functional tRNA. Like rRNA, it is a non-coding RNA and a valid product of transcription, but it is not the primary answer when considering the general output of transcription for gene expression.ConclusionEukaryotic gene expression is characterized by a spatial and functional separation between transcription and translation, facilitated by the nuclear envelope. This allows for extensive RNA processing before the message leaves the nucleus. The immediate product of transcribing a protein-coding gene is the pre-mRNA molecule. This distinction between primary transcript and mature product is a key difference between prokaryotes (where transcription directly produces mRNA) and eukaryotes. Recognizing pre-mRNA as the initial product is fundamental to understanding post-transcriptional regulation and the flow of genetic information in eukaryotic cells.

In eukaryotes, what does transcription produce?

A
mRNA

B
pre-mRNA

C
rRNA

D
tRNA

In eukaryotes, transcription of protein-coding genes produces pre-mRNA.

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In eukaryotes, what does transcription produce?

A mRNA B pre-mRNA C rRNA D tRNA

In eukaryotes, transcription of protein-coding genes produces pre-mRNA.

Topic Flashcards

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Related Questions

A
mRNA

B
pre-mRNA

C
rRNA

D
tRNA