Transcription Process Overview

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What is required for eukaryotic transcription initiation in vivo?

Chromatin-modifying enzymes

Mediator protein complex (correct)

RNA polymerase II

Transcriptional activators

Which proteins are involved in facilitating the assembly of the transcription initiation machinery onto DNA in eukaryotic cells?

Histone-modifying enzymes

Mediator protein complex

RNA polymerase II

Chromatin remodeling complexes (correct)

How many individual subunits approximately need to assemble at the start point of transcription to initiate transcription in a eukaryotic cell?

Well over 100 subunits (correct)

Around 50 subunits

Exactly 100 subunits

Less than 100 subunits

What is necessary for RNA polymerase II to begin transcribing?

Release from a large complex of proteins Signup and view all the answers

What characterizes the movement of RNA polymerase after transcription initiation?

Jerkily, pausing at some DNA sequences Signup and view all the answers

What happens after the process of abortive initiation is overcome?

The core enzyme breaks free of interactions with the promoter DNA. Signup and view all the answers

What happens when the polymerase encounters a terminator signal?

The polymerase releases both the newly made RNA molecule and the DNA template. Signup and view all the answers

What is the role of the σ factor in transcription termination?

It aids in forming a hairpin structure at the terminator signal. Signup and view all the answers

How does the transcription bubble change as the polymerase moves down the DNA?

It continually expands at the front and contracts at the rear of the polymerase. Signup and view all the answers

What characterizes a termination signal in most bacterial genes?

A sequence rich in adenine-thymine pairs. Signup and view all the answers

What is the role of TFIIH in the transcription initiation complex formation?

Unwinding the DNA by hydrolyzing ATP Signup and view all the answers

What is the significance of the C-terminal domain (CTD) of RNA polymerase during transcription initiation?

Receives phosphate groups necessary for conformational changes Signup and view all the answers

Which subunit of TFIIH enables RNA polymerase II to move away from the promoter and enter elongation?

Kinase Signup and view all the answers

What is the function of RNA polymerase II at the promoter before entering the elongation phase?

Synthesizing long lengths of RNA Signup and view all the answers

How does RNA polymerase II gain access to the template strand at the transcription start point?

By unwinding the DNA with a DNA helicase Signup and view all the answers

Which DNA sequence is considered the most important for most polymerase II promoters for transcription initiation?

TATA box sequence Signup and view all the answers

What is the function of TFIID in transcription initiation?

Induces a large distortion in the TATA box DNA Signup and view all the answers

Which statement accurately describes the role of TFIIB in transcription initiation?

Accurately positions RNA polymerase at the start site of transcription Signup and view all the answers

Where are most of the DNA sequences that influence transcription initiation located in relation to the transcription start point?

Upstream Signup and view all the answers

What role does the DPE sequence play in transcription initiation?

Brings DNA sequences closer together at the promoter Signup and view all the answers

What is the function of the sigma (σ) factor in the RNA polymerase holoenzyme complex?

Assisting in reading signals in DNA to locate the starting point for transcription Signup and view all the answers

What is the role of the transcription bubble during RNA synthesis?

Acting as a template for complementary base-pairing with ribonucleotides Signup and view all the answers

What happens when the polymerase holoenzyme slides into a promoter sequence?

It binds tightly to the DNA due to specific interactions with σ factor Signup and view all the answers

Why does the RNA polymerase holoenzyme dissociate when it collides with bacterial DNA?

Due to weak binding between the core enzyme and σ factor Signup and view all the answers

What is the main reason why several attempts to start polymerization often do not succeed?

Multiple possible sites for initiation that fail to initiate synthesis Signup and view all the answers

What happens to most of the general transcription factors once RNA polymerase II begins elongating the RNA transcript?

They are released from the DNA to initiate another round of transcription. Signup and view all the answers

What additional function does the phosphorylation of the tail of RNA polymerase II serve?

It allows for components of the RNA-processing machinery to load onto the polymerase. Signup and view all the answers

How does DNA packaging in eukaryotic cells affect transcription initiation complexity?

It complicates initiation, requiring more proteins due to nucleosome packaging. Signup and view all the answers

What role do activator, mediator, and chromatin-modifying proteins play in eukaryotic transcription initiation?

They are required for the assembly of the transcription initiation machinery onto DNA. Signup and view all the answers

How do processing proteins interact with the nascent RNA molecule during transcription?

They hop from the polymerase tail onto the emerging RNA to begin processing. Signup and view all the answers

What is the main difference in the type of nucleotides linked by RNA polymerase compared to DNA polymerase?

Ribonucleotides instead of deoxyribonucleotides Signup and view all the answers

What unique capability does RNA polymerase have in initiating RNA chains compared to DNA polymerases?

Can start without a primer Signup and view all the answers

How does the processivity of RNA polymerase differ from that of DNA polymerases?

RNA polymerases are absolutely processive, DNA polymerases are not Signup and view all the answers

What characterizes the initiation of transcription in gene expression?

The point at which the cell regulates protein production Signup and view all the answers

How does the recognition of start and stop points by RNA polymerase differ between bacteria and eukaryotes?

It differs somewhat between the two Signup and view all the answers

What is a significant feature of RNA polymerases regarding dissociation from the DNA template during transcription?

Must finish without dissociating Signup and view all the answers

What is one key role of initiation in transcription in regulating gene expression?

Determining which proteins are produced and at what rate Signup and view all the answers

How does the ability to start an RNA chain without a primer benefit RNA polymerase?

Increases efficiency in gene transcription Signup and view all the answers

'Processivity' in terms of RNA polymerases refers to:

'Finishing' an RNA molecule without interruptions Signup and view all the answers

'Signals Encoded in DNA Tell RNA Polymerase Where to Start and Stop' - This statement highlights:

'Recognition' points for initiation and termination of transcription Signup and view all the answers