In eukaryotic cells, transcription cannot begin until a. the two DNA strands have completely separated and exposed the promoter. b. several transcription factors have bound to the promoter. c. the 5′ caps are removed from the mRNA. d. the DNA introns are removed from the template.

Verified step by step guidance

1. Step 1: Understand the process of transcription. Transcription is the first step of gene expression, where a particular segment of DNA is copied into RNA (especially mRNA) by the enzyme RNA polymerase.
2. Step 2: Identify the role of the promoter. The promoter is a region of DNA that initiates transcription of a particular gene. It's where RNA polymerase binds to start transcription.
3. Step 3: Consider the options. Option a suggests that the DNA strands must completely separate before transcription can begin. While it's true that the DNA strands must separate for transcription to occur, they don't need to completely separate, just enough to expose the promoter region.
4. Step 4: Evaluate the remaining options. Option c and d refer to processes that occur after transcription has already begun. The 5′ cap is added to the mRNA during processing after transcription, and introns are removed from the mRNA during splicing, also after transcription.
5. Step 5: The correct answer is b. Several transcription factors must bind to the promoter before transcription can begin. These transcription factors help to position the RNA polymerase correctly at the promoter and are necessary for transcription initiation.

Key Concepts

Transcription Factors

Transcription factors are proteins that bind to specific DNA sequences, facilitating the recruitment of RNA polymerase to the promoter region of a gene. They play a crucial role in regulating gene expression by either promoting or inhibiting the transcription process. In eukaryotic cells, the binding of multiple transcription factors is essential for the initiation of transcription.

Promoter Region

The promoter region is a specific sequence of DNA located upstream of a gene that serves as the binding site for RNA polymerase and transcription factors. It contains essential elements that determine the start site of transcription and the efficiency of gene expression. The proper exposure and recognition of the promoter are critical for the initiation of transcription in eukaryotic cells.

Eukaryotic Transcription Process

In eukaryotic cells, transcription is a multi-step process that involves the synthesis of RNA from a DNA template. This process requires the unwinding of DNA, the assembly of transcription factors and RNA polymerase at the promoter, and the elongation of the RNA strand. Unlike prokaryotes, eukaryotic transcription also involves post-transcriptional modifications, such as capping and splicing, before the mRNA is translated.