Lecture 2/19/25 Flashcards
Transcription
What is the role of mRNA?
It carries genetic information from DNA to ribosomes for protein synthesis.
What does tRNA do?
It delivers specific amino acids to the ribosome during translation.
What is the function of rRNA?
It forms the structural and catalytic core of ribosomes.
What are the core subunits of bacterial RNA polymerase?
Two α subunits, one β, one β’, one ω, and a sigma factor for initiation.
How many RNA polymerases do prokaryotes have?
One.
How many RNA polymerases do eukaryotes have?
Three (Pol I, Pol II, Pol III).
What is the transcription bubble?
A small region of unwound DNA where RNA synthesis occurs.
What is the role of the ‘pin’ in RNA polymerase?
It helps keep the DNA strands separated within the transcription bubble.
What is a promoter sequence?
A DNA segment upstream of a gene that signals where transcription should begin.
Why is the promoter important?
It directs RNA polymerase to the correct start site, regulating gene expression.
What are transcription factors?
Proteins that assist in regulating RNA polymerase binding and gene expression.
What is the role of the bacterial sigma factor?
It directs RNA polymerase to specific promoter sequences during initiation.
What is a housekeeping gene?
A gene that is constantly expressed to maintain basic cellular functions.
What is the basic structure of a gene?
A promoter, a coding region (starting with ATG), and regulatory elements (plus introns/exons in eukaryotes).
Why must the sigma factor dissociate after initiation?
To free the RNA exit channel so RNA polymerase can elongate the transcript efficiently.
