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Questions and Answers
In which direction is RNA synthesized during transcription?
In which direction is RNA synthesized during transcription?
What role does RNA polymerase play in transcription?
What role does RNA polymerase play in transcription?
What occurs at the promoter during transcription?
What occurs at the promoter during transcription?
During the process of elongation in transcription, what is true about the DNA template strand?
During the process of elongation in transcription, what is true about the DNA template strand?
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Which of the following describes the relationship between RNA and the DNA template during transcription?
Which of the following describes the relationship between RNA and the DNA template during transcription?
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What role does the σ subunit play in prokaryotic transcription?
What role does the σ subunit play in prokaryotic transcription?
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Which component of prokaryotic RNA polymerase is responsible for the 5' to 3' RNA polymerase activity?
Which component of prokaryotic RNA polymerase is responsible for the 5' to 3' RNA polymerase activity?
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What does the transcription unit in prokaryotes extend from?
What does the transcription unit in prokaryotes extend from?
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What is a primary property of prokaryotic RNA polymerase?
What is a primary property of prokaryotic RNA polymerase?
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How many peptide subunits make up the core enzyme of prokaryotic RNA polymerase?
How many peptide subunits make up the core enzyme of prokaryotic RNA polymerase?
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During transcription initiation, where does RNA polymerase bind to start the process?
During transcription initiation, where does RNA polymerase bind to start the process?
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Which of the following is NOT a characteristic of the prokaryotic RNA polymerase?
Which of the following is NOT a characteristic of the prokaryotic RNA polymerase?
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Which part of the prokaryotic RNA polymerase is composed of both the core enzyme and the σ factor?
Which part of the prokaryotic RNA polymerase is composed of both the core enzyme and the σ factor?
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What is the role of the Pribnow box in transcription?
What is the role of the Pribnow box in transcription?
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Which sequence is located about 35 nucleotides upstream of the initial base of mRNA during transcription?
Which sequence is located about 35 nucleotides upstream of the initial base of mRNA during transcription?
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Which statement accurately describes RNA polymerase?
Which statement accurately describes RNA polymerase?
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During the initiation of transcription, what happens after RNA polymerase binds to the promoter?
During the initiation of transcription, what happens after RNA polymerase binds to the promoter?
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What is released each time a nucleotide is added by RNA polymerase during transcription?
What is released each time a nucleotide is added by RNA polymerase during transcription?
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In what way does RNA polymerase differ from DNA polymerase?
In what way does RNA polymerase differ from DNA polymerase?
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What occurs during the elongation phase of transcription?
What occurs during the elongation phase of transcription?
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Which of the following is NOT required by RNA polymerase during transcription?
Which of the following is NOT required by RNA polymerase during transcription?
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What is the initial step in the transcription process?
What is the initial step in the transcription process?
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During which phase of transcription does the RNA transcript get elongated?
During which phase of transcription does the RNA transcript get elongated?
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What role does the ρ-factor (rho) play in transcription?
What role does the ρ-factor (rho) play in transcription?
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What happens to the DNA strands after transcription is completed?
What happens to the DNA strands after transcription is completed?
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What does the ‘G’ nucleotide in DNA specify during RNA synthesis?
What does the ‘G’ nucleotide in DNA specify during RNA synthesis?
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In which direction does RNA elongation occur during transcription?
In which direction does RNA elongation occur during transcription?
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During DNA transcription, which direction does RNA elongation occur?
During DNA transcription, which direction does RNA elongation occur?
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What does RNA polymerase bind to at the start of transcription?
What does RNA polymerase bind to at the start of transcription?
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What best describes the relationship between the template strand of DNA and the RNA transcript?
What best describes the relationship between the template strand of DNA and the RNA transcript?
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What is specified by the nucleotide adenine (A) in the RNA sequence during transcription?
What is specified by the nucleotide adenine (A) in the RNA sequence during transcription?
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What happens to the DNA strands after the elongation of RNA transcription?
What happens to the DNA strands after the elongation of RNA transcription?
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What occurs when RNA polymerase reaches the termination sequence?
What occurs when RNA polymerase reaches the termination sequence?
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Which term describes the process where the RNA polymerase stops elongation?
Which term describes the process where the RNA polymerase stops elongation?
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In RNA, what replaces thymine (T) found in DNA?
In RNA, what replaces thymine (T) found in DNA?
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As RNA is synthesized, which base pairs with cytosine (C) from the DNA template?
As RNA is synthesized, which base pairs with cytosine (C) from the DNA template?
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What is the function of the sigma factor in transcription?
What is the function of the sigma factor in transcription?
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Which of the following sequences correctly represents the RNA transcription process described?
Which of the following sequences correctly represents the RNA transcription process described?
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What role does the Rho factor play in transcription?
What role does the Rho factor play in transcription?
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Which box is a consensus sequence located about 25 nucleotides left of the initial base in eukaryotic promoters?
Which box is a consensus sequence located about 25 nucleotides left of the initial base in eukaryotic promoters?
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During RNA synthesis, which base pairs with adenine in the RNA strand?
During RNA synthesis, which base pairs with adenine in the RNA strand?
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In the transcription process, which of the following occurs after the core enzyme binds to the promoter?
In the transcription process, which of the following occurs after the core enzyme binds to the promoter?
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What characterizes a palindrome in the context of nucleic acid sequences?
What characterizes a palindrome in the context of nucleic acid sequences?
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Which of the following best explains why the CAAT box is relevant in eukaryotic transcription?
Which of the following best explains why the CAAT box is relevant in eukaryotic transcription?
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Study Notes
Biochemistry of Cells - SIJ1003
- Course code: SIJ1003
- Course title: Biochemistry of Cell
- Date: 31 DEC 2024
- Week: 12
Animations and Resources
- Transcription animation: https://www.youtube.com/watch?v=ztnfrVHDJbQ
Central Dogma: Flow of Genetic Information
- DNA → RNA → Protein
- Processes: Replication, Transcription, Translation, Reverse Transcription
Protein Synthesis in Prokaryotes vs Eukaryotes
-
Prokaryotes (Bacterial Cells):
- Transcription and translation occur in the cytoplasm simultaneously
- No nucleus
- Naked DNA
- mRNA transcribed directly from DNA template is immediately ready for translation
-
Eukaryotes (Animal Cells):
- Transcription occurs in the nucleus, translation in the cytoplasm
- DNA in chromosomes
- mRNA is processed in the nucleus before leaving for the cytoplasm
Transcription in Prokaryotes
-
Transcription Unit:
- Stretches from a promoter to a terminator
- Promoter: DNA sequence where RNA polymerase binds
- Terminator: DNA sequence signaling the end of transcription
-
Core Enzyme:
- Composed of (2 α, β and β’ )
- Responsible for 5’→3’ RNA polymerase activity
-
σ subunit (σ factor):
- Enables RNA polymerase to recognize the promoter region
-
Holoenzyme:
- σ factor plus the core enzyme
- Recognizes the promoter
-
Properties of Prokaryotic RNA Polymerase:
- Multi-subunit enzyme; recognizes promoter sequences
- Makes a complementary RNA copy of DNA template
- Recognizes terminator sequences
Steps in Transcription
-
Initiation: RNA polymerase binds to the promoter region
- Nucleotide sequences recognized by RNA polymerase are: Pribnow box and -35 region
- Elongation: RNA synthesis proceeds 5' → 3'
- Termination: RNA polymerase recognizes termination regions on the DNA template (p-independent termination)
mRNA - Prokaryotes
- No processing steps
- Does not require a promoter
- No removal of introns
Transcription in Eukaryotes
-
Eukaryotic Promoter region:
- TATA box or Hogness box: consensus sequences about 25 nucleotides to the left of the initial base of the DNA
- CAAT box: consensus sequences around 70-80 nucleotides to the left of the initial base of the DNA
-
Three distinct RNA polymerase species:
- RNA polymerase I: produces ribosomal RNAs
- RNA polymerase II: produces messenger RNAs
- RNA polymerase III: produces transfer RNAs and small ribosomal RNAs
Post Modification to RNA Eukaryotes
-
5’ capping:
- 7-methylguanylate is added to the 5' end of nascent pre-mRNA
-
Addition of a poly(A) tail:
- A chain of adenine nucleotides to the 3' end of the mRNA
-
Removal of introns:
- Removes non-coding regions (introns)
- Splicing connects coding regions (exons)
RNA Processing/Splicing
- Primary transcript (pre-mRNA) undergoes processing steps in the nucleus to become mature mRNA
- Introns (non-coding regions) are removed and exons (coding regions) are joined together
Prokaryotes vs. Eukaryotes
-
Prokaryotes:
- No nucleus
- Transcription and translation occur simultaneously in the cytoplasm
-
Eukaryotes:
- Transcription occurs in the nucleus
- Translation occurs in the cytoplasm
- mRNA processing steps
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Description
Test your knowledge on the biochemistry of cells, focusing on the central dogma of molecular biology and the protein synthesis processes in prokaryotes and eukaryotes. This quiz covers transcription, translation, and the differences between bacterial and animal cells. Prepare to explore the intricate details of genetic information flow!
