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Questions and Answers
What is the first step in gene expression?
Where does eukaryotic transcription take place?
What are the three sequential stages of eukaryotic transcription?
What is the function of RNA polymerases in transcription?
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What is transcribed during transcription?
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What do RNA polymerases detect during transcription?
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Which RNA polymerase is responsible for transcribing all mRNAs, some snRNAs, siRNAs, and all microRNAs?
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Which RNA polymerase catalyzes the transcription of all rRNA genes except 5S?
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Which RNA polymerase transcribes small untranslated RNAs essential for certain cellular functions, including tRNAs?
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Which component is NOT required for RNA transcription by RNA polymerase?
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What is the fundamental reaction of RNA synthesis?
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What does the pre-mRNA undergo before exiting into the cytoplasm through the nuclear pore complex?
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Which structure of the nucleus is responsible for the transcription of rRNA genes?
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What initiates the separation of the DNA strands during the initiation of transcription by RNA polymerase?
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$5'$ to $3'$ direction is characteristic of which process?
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$RNA$ polymerase is less effective at correcting mistakes compared to DNA polymerase due to:
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What are the three sequential stages of eukaryotic transcription?
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What is the function of RNA polymerases in transcription?
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Which RNA polymerase catalyzes the transcription of all rRNA genes except 5S?
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What does the pre-mRNA undergo before exiting into the cytoplasm through the nuclear pore complex?
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What initiates the separation of the DNA strands during the initiation of transcription by RNA polymerase?
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Why is RNA polymerase less effective at correcting mistakes compared to DNA polymerase?
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What is the function of RNA polymerase II?
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Where does the transcription of rRNA genes take place?
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What is the fundamental difference between RNA synthesis and DNA synthesis?
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What components are required for RNA transcription by RNA polymerase?
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What is the initiating event for the separation of DNA strands during the initiation of transcription by RNA polymerase?
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What cellular structure is responsible for the transcription of small untranslated RNAs essential for certain cellular functions, including tRNAs?
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What is the primary product of RNA polymerase I transcription?
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What is the primary function of RNA polymerase III?
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What drives the synthesis of RNA in the 5’ to 3’ direction?
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What is the enzymatic activity responsible for the formation of a complementary RNA strand during transcription?
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Study Notes
Gene Expression and Transcription
- Gene expression begins with transcription, the process that transfers genetic information from DNA to RNA.
- Eukaryotic transcription occurs in the nucleus, where DNA is housed.
Stages of Eukaryotic Transcription
- Three sequential stages of eukaryotic transcription: initiation, elongation, and termination.
Role of RNA Polymerases
- RNA polymerases are enzymes that synthesize RNA from a DNA template during transcription.
- They detect specific DNA sequences known as promoter regions to initiate transcription.
Types of RNA Polymerases
- RNA polymerase II is responsible for transcribing all mRNAs, some snRNAs, siRNAs, and all microRNAs.
- RNA polymerase I catalyzes the transcription of all rRNA genes except for the 5S rRNA.
- RNA polymerase III transcribes small untranslated RNAs, such as tRNAs, which are essential for cellular functions.
Requirements for Transcription
- RNA transcription by RNA polymerase does not require a primer, differentiating it from DNA synthesis.
- Essential components for RNA transcription include DNA template, ribonucleotides (ATP, CTP, GTP, UTP), and transcription factors.
RNA Synthesis Process
- The fundamental reaction of RNA synthesis is the addition of nucleotides to the growing RNA chain in the 5' to 3' direction.
- During the initiation of transcription, RNA polymerase initiates the separation of DNA strands, driven by the binding of transcription factors and polymerase to the promoter.
Processing of Pre-mRNA
- Pre-mRNA undergoes modifications such as capping, polyadenylation, and splicing before exiting the nucleus through the nuclear pore complex.
Transcription Structures in the Nucleus
- The nucleolus, a specialized structure within the nucleus, is responsible for the transcription of rRNA genes.
- The nucleus also contains the transcription machinery for small untranslated RNAs.
Efficiency and Correction Mechanisms
- RNA polymerase is less effective at correcting mistakes during RNA synthesis compared to DNA polymerase due to the absence of proofreading mechanisms.
- This lower fidelity makes RNA polymerase more error-prone than DNA polymerase.
Enzymatic Activity in RNA Synthesis
- The enzymatic activity that catalyzes the formation of a complementary RNA strand involves synthesizing RNA by adding ribonucleotides in the correct sequence specified by the DNA template.
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Description
Test your knowledge about gene expression, transcription, and the types of RNA involved in the process such as mRNA, tRNA, and rRNA. Explore the intricacies of DNA transcription and translation into proteins.
