Chapter 8: Transcription Flashcards
the copying of one strand of the DNA (the coding strand) into an RNA molecule (transcript)
transcription
enzyme that transcribes DNA into RNA
RNA polymerase
RNA polymerase copies the coding strand of DNA by using the ()
complementary (template/non-coding) strand
RNA polymerase separates the DNA strands and allows () to base pair with template strand
ribonucleoside triphosphates
types of RNAs that are produced
- mRNA (encode proteins)
- non-coding RNAs (regulatory, catalytic, or structural roles)
3 stages of transcription
- initiation
- elongation
- termination
transcription starts when RNA polymerase binds to DNA sequence just preceding the gene: (); signifies start site for transcription
promoter
first base to be transcribed; denoted +1
transcription start site (TSS)
if RNA is transcribed in the 5’ to 3’ direction, the template must be read in the () direction
3’ to 5’
on the RNA, bases 3’ of a site are (1), while bases 5’ of a site are (2)
- downstream
- upstream
during initiation, RNA polymerase separates DNA strands to make a ()
transcription bubble
during initiation, the first few ribonucleoside triphosphates are added while ()
RNA polymerase is still at promoter
RNA polymerase moves past promoter and changes conformation to be more stably associated with DNA when RNA is ()
a sufficient size
transcription stage where RNA polymerase moves along the DNA, adding ribonucleotides
elongation
how is the transcription bubble maintained during transcription elongation
DNA re-pairs behind RNA polymerase as the enzyme unwinds DNA ahead
elongation continues until the polymerase meets a DNA sequence called a () that signals RNA synthesis to cease
terminator
in chromatin-packaged DNA, () prevent transcription machinery binding to DNA
nucleosomes
3 additional types of enzymes required in eukaryotic transcription
- nucleosome remodeling enzymes
- histone chaperones
- enzymes that reversibly modify histone proteins
enzymes that reposition histones away from DNA to be transcribed; can also work to block transcription
nucleosome remodeling enzymes
enzymes that disassemble and reassemble the histone octamer
histone chaperone
some enzymes can reversibly modify histone proteins; these modified proteins ()
recruit specific proteins to certain DNA regions
eukaryotes have 3 RNA polymerases
RNA polymerase I to III
eukaryotic RNA polymerase that transcribes large ribosomal RNA (rRNA) genes
RNA Pol I
eukaryotic RNA polymerase that transcribes messenger RNA (mRNA) genes
RNA Pol II