87 Questions
What is the main difference between transcription in eukaryotes and bacteria?
The genetic material is located in the nucleus in eukaryotes
What is the function of the 3 RNA polymerases in the nucleus?
To transcribe the genetic information
What happens to the transcripts produced in the nucleus?
They are transported to the cytoplasm for translation
What is unique about the RNA polymerases found in mitochondria and chloroplasts?
They are similar to those found in bacteria
What is the effect of chromatin organization on transcription?
It exercises a negative control over transcription
What is a characteristic of archaea in terms of their transcription process?
Their transcription process is similar to that of eukaryotes
What type of control is commonly used in prokaryotes?
Negative control
What is the main difference between eukaryotic and prokaryotic genomes?
Eukaryotic genomes have more non-coding DNA
What is the function of general transcription factors (GTF)?
To initiate transcription
What is the result of RNA polymerase moving along the DNA?
Supercoiling of DNA
What is the function of chromatin remodelers?
To move nucleosomes
How many RNA polymerases are found in eukaryotes?
7
What is the function of RNA Pol IV and RNA Pol V in plants?
To regulate gene expression
What is the name of the structure formed by the RNA Pol I transcript?
Nucleolus
What is the significance of the linker sequences in chromatin?
They are inaccessible to transcription factors
What is the result of the interaction between chromatin and transcription?
Mutual influence on each other
Which RNA polymerase transcribes the majority of genes?
RNA Pol II
What is the main function of RNA Pol III?
To transcribe tRNAs
How many subunits make up the core of eukaryotic RNA polymerases?
10 subunits
What is the name of the subcomplex found in RNA Pol II, but not in RNA Pol I and III?
Rpb4/Rpb7
Which RNA polymerase has a unique trimeric subcomplex?
RNA Pol III
What is the proposed evolutionary origin of RNA Pol I and III?
They evolved from RNA Pol II
What is the name of the transcription factor that is similar to the C82/C34/C31 trimer in RNA Pol III?
TFIIE
How many genes are transcribed by RNA Pol II?
Between 5,000 to 50,000
What is the name of the subunit shared by RNA Pol I and III, but not by RNA Pol II?
AC19
What is the structure of the RNA polymerase in bacteria?
A hand-like structure
What is the primary reason why RNA Pol I consumes a significant amount of NTPs in the cell?
It transcribes multiple copies of the same gene that are repeated in the chromosomes.
What is the main difference between the structure of RNA polymerases in bacteria and eukaryotes?
The length of the domains is different.
How many subunits does the RNA Pol II of eukaryotes have?
12
What is the function of the C17/C25 subcomplex in the RNA Pol III of eukaryotes?
The function is unknown.
What is the primary function of RNA Pol III in eukaryotes?
It transcribes tRNAs, rRNA 5S, and other small RNAs.
How do the RNA polymerases of eukaryotes and archaea differ in terms of their complexity?
Eukaryotic RNA polymerases are more complex.
What is the effect of α-amanitina on RNA polymerases?
It blocks the movement of RNA Pol II.
What is the main reason why RNA Pol II transcribes molecules of intermediate size?
Because it transcribes a wide variety of RNA molecules.
How many RNA polymerases are present in the first eukaryote?
3
What is the primary difference between RNA Pol I and RNA Pol III in terms of the length of the RNA molecules they transcribe?
RNA Pol I transcribes longer molecules.
What is the function of the C-terminal domain (CTD) of the Rpb1 subunit in RNA Pol II?
To regulate the transcription process
What is the location of the active center of RNA Pol II?
Between the Rpb1 and Rpb2 subunits
What is the significance of the 'hand' structure in RNA Pol II?
It is a conserved structure in all polymerases
What is the role of the accessory subunits in RNA Pol II?
To surround the large subunits
Why is the Rpb4/Rpb7 dimer not always present in RNA Pol II?
It can enter and leave the enzyme
What is the percentage of genes transcribed by RNA Pol II in eukaryotes?
20-40%
What is unique about the subunit A12.2 in RNA Pol I?
It has functions of TFIIS and Rpb9
What is the function of the trimeric subcomplex in RNA Pol III?
To initiate transcription rapidly
What is the main difference between the subunit 1 of RNA Pol I and RNA Pol II?
The absence of a CTD domain
What is the function of the subcomplex A49/A34.5 in RNA Pol I?
To initiate transcription
What is the main difference between the structure of RNA Pol I and RNA Pol II?
The absence of a CTD domain
What is the function of the subunit A190 in RNA Pol I?
To initiate transcription
What is the main difference between the subunits 2 of RNA Pol I and RNA Pol II?
The similarity in their sequences
What is the function of the trimeric subcomplex in RNA Pol I?
To help in the release of paused RNA polymerase
What is the approximate angle of DNA bending during transcription by RNA Pol II?
90º
Which part of the RNA Pol II complex is involved in selecting the transcription start site?
Rpb9
What is the main difference between the subunits A49/A34.5 and A14/43?
Their function in transcription
What is the function of the subunit A135 in RNA Pol I?
To interact with general transcription factors
What is the primary function of the CTD domain of Rpb1?
Regulation of gene expression
How many times is the conserved sequence of 7 amino acids repeated in the CTD domain of Rpb1 in mammals?
52
What is the consequence of deleting more than half of the CTD repeats?
Lethal
What is the relationship between the length of the CTD domain and the complexity of the genome?
The length of CTD is directly proportional to the complexity of the genome
Which amino acids in the CTD domain can be phosphorylated?
Tyr, Ser, and Thr
What is the consequence of phosphorylating the CTD domain?
Recruitment of transcription factors
What is the unique feature of the CTD domain in terms of its structure?
It is highly flexible and dynamic
What is the primary difference between RNA Pol II and other RNA polymerases in terms of its subunit composition?
It has a smaller subunit composition
What is the main reason for the high conservation of sequence among eukaryotic RNA polymerases, particularly in the catalytic domain?
The high degree of sequence conservation is necessary for the enzyme's catalytic activity.
What is the primary function of the positively charged amino acids in the RNA polymerase's active site?
To interact with the negatively charged DNA phosphate backbone.
What is the main difference between the RNA polymerase of yeast and E. coli in terms of sequence conservation?
The RNA polymerase of yeast and E. coli have a similar degree of sequence conservation.
What is the function of the RNA polymerase's Rpb1 subunit?
To provide the main architecture of the RNA polymerase.
What is the significance of the RNA polymerase's subdomains in terms of its structure and function?
The subdomains provide structural flexibility to the RNA polymerase during transcription.
What is the primary function of the RNA polymerase's modules during transcription?
To provide structural flexibility to the RNA polymerase during transcription.
What is the result of the RNA polymerase's movement along the DNA during transcription?
The RNA polymerase reads the DNA template and separates the DNA strands.
What is the significance of the RNA polymerase's interaction with the DNA phosphate backbone?
The interaction facilitates the binding of RNA polymerase to the template strand.
What is the primary function of the RNA polymerase's subunits during transcription?
To form a complex with other subunits to transcribe DNA.
What is the result of the RNA polymerase's conformational changes during transcription?
The RNA polymerase can synthesize the RNA transcript more efficiently.
What is the function of the subunit A12.2 in RNA Pol I?
To solve problems of RNA polymerase pausing
What is the role of the TFIIS factor in RNA Pol II?
To help the RNA polymerase overcome pausing problems
What is the characteristic of the RNA Pol I transcript?
It is a long molecule that forms a tree-like structure
What is the function of the RNA Pol I in eukaryotes?
To transcribe the gene that codes for the ribosomal RNA
What is the function of the nucleolus in eukaryotes?
To transcribe and process ribosomal RNA
What is the function of the promoter region in the genome?
To initiate transcription
What is the function of the DNA region between two transcribing regions?
To separate two genes
What is the role of UBF in the core promoter?
To bind to another sequence upstream and induce DNA folding
What is the composition of the SL1 complex?
TBP, TAF1A, TAF1C, and TAF1D
What is the result of the interaction between UBF and SL1 in the core promoter?
The DNA is folded and the RNA polymerase is attracted
What is the structure of the rRNA genes in human chromosomes?
Tandem repeats of a gene with a coding region and a spacer region
What is the role of the topoisomerase in the transcription of rRNA genes?
To relax the DNA supercoiling during transcription
What is the structure of the chromatin in the transcribed region of the rRNA genes?
Nucleosomes are absent in the transcribed region but present in the spacer region
What is the result of the RNA polymerase reaching the termination zone?
The RNA polymerase is released from the DNA and the RNA
What is the characteristic of the transcription units in the rRNA genes?
Some units are transcribed while others are not
Learn about the transcription process in eukaryotes, including the differences with bacterial transcription, the complexity of RNA polymerases, and the spatial and temporal separation of transcription and translation processes.
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