Question
During transcription in eukaryotes, a type of RNA polymerase called RNA polymerase II moves along the template strand of the DNA in the 3'→5' direction. However, for any given gene, either strand of the double-stranded DNA may function as the template strand.
For any given gene, what ultimately determines which DNA strand serves as the template strand?
View Available Hint(s)for Part B
the location of specific proteins (transcription factors) that bind to the DNA
the location along the chromosome where the double-stranded DNA unwinds
which of the two strands of DNA carries the RNA primer
the base sequence of the gene's promoter
Part C - RNA processing
After transcription begins, several steps must be completed before the fully processed mRNA is ready to be used as a template for protein synthesis on the ribosomes.
Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus?
View Available Hint(s)for Part C
A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.
Coding sequences called exons are spliced out by ribosomes.
A translation stop codon is added at the 3' end of the pre-mRNA.
Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes.
A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.
For any given gene, what ultimately determines which DNA strand serves as the template strand?
View Available Hint(s)for Part B
the location of specific proteins (transcription factors) that bind to the DNA
the location along the chromosome where the double-stranded DNA unwinds
which of the two strands of DNA carries the RNA primer
the base sequence of the gene's promoter
Part C - RNA processing
After transcription begins, several steps must be completed before the fully processed mRNA is ready to be used as a template for protein synthesis on the ribosomes.
Which three statements correctly describe the processing that takes place before a mature mRNA exits the nucleus?
View Available Hint(s)for Part C
A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.
Coding sequences called exons are spliced out by ribosomes.
A translation stop codon is added at the 3' end of the pre-mRNA.
Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes.
A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.
Answers
GPT-4o mini
**Part B - Determining the Template Strand:**
For any given gene, the strand that ultimately serves as the template strand is determined by:
- **The base sequence of the gene's promoter.**
The promoter region is a specific sequence of DNA where transcription factors and RNA polymerase bind. This binding will determine which strand will be transcribed into RNA.
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**Part C - RNA Processing:**
The three statements that correctly describe the processing that takes place before a mature mRNA exits the nucleus are:
1. **A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.**
2. **Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes.**
3. **A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.**
These modifications are essential for mRNA stability, export from the nucleus, and recognition by the ribosome during translation. The statement about coding sequences (exons) being spliced out is incorrect, as exons are retained in the mature mRNA.
For any given gene, the strand that ultimately serves as the template strand is determined by:
- **The base sequence of the gene's promoter.**
The promoter region is a specific sequence of DNA where transcription factors and RNA polymerase bind. This binding will determine which strand will be transcribed into RNA.
---
**Part C - RNA Processing:**
The three statements that correctly describe the processing that takes place before a mature mRNA exits the nucleus are:
1. **A cap consisting of a modified guanine nucleotide is added to the 5' end of the pre-mRNA.**
2. **Noncoding sequences called introns are spliced out by molecular complexes called spliceosomes.**
3. **A poly-A tail (50-250 adenine nucleotides) is added to the 3' end of the pre-mRNA.**
These modifications are essential for mRNA stability, export from the nucleus, and recognition by the ribosome during translation. The statement about coding sequences (exons) being spliced out is incorrect, as exons are retained in the mature mRNA.