Lecture 11: Transcription Flashcards
Difference between ribose and deoxyribose
Ribose has 2’ OH
Definition of gene
Segment of DNA containing the information for a single polypeptide chain or functional RNA
Signs for upstream and downstream, and site at which transcription begins
Upstream is (-), downstream is (+), transcription is +1
Direction of template strand
3’ to 5’ (same direction that RNA polymerase reads)
At which sites is the promoter often found in prokaryotes? Also give the specific sequences
-35 (TTGACA) and -10 (TATATT) (both upstream)
Closed complex vs open complex
Closed complex is when DNA hasn’t denatured yet, open complex is one RNA pol has opened the DNA molecule
Structure of Rho-independent transcription termination (intrinsic terminators)
G/C rich sequence followed by A-rich sequence
What happens in a Rho-independent transcription terminator?
RNA-RNA Stem loop forms between Gs and Cs in stem (bind with 3 H bonds instead of 2) - transcript folds to form termination hairpin and RNA chain released
Subunits of prokaryotic RNA polymerase
alpha1, alpha2, ß, ß’, omega (core enzyme)
Functions of ß and ß’ sites
ß is active site, ß’ is the structure that binds to DNA
Reaction involved in RNA polymerization
Nucleophilic attack by 3’ oxygen of growing RNA chain on a phosphate (alpha phosphate) of the next nucleotide to be added - energetically favorable and forms phosphodiester bond
Components of RNA polymerase holoenzyme
RNA (core) polymerase and σ70 factor
Function of sigma (σ) factor
Subunit of RNA polymerase that recognizes and binds to promoter
Definition of polycistronic
1 promoter regulates 1 mRNA, which makes multiple polypeptides (often in prokaryotic genes)
Definition of monocistronic
1 promoter regulates 1 mRNA, which makes 1 protein (usually in eukaryotic genes)
Eukaryotic RNA polymerase (II) version of ß and ß’ subunits
RPB2 (ß’) and RPB1 (ß)
Eukaryotic RNA polymerase I function
Transcribe precursor ribosomal RNA
Eukaryotic RNA pol II function
Transcribe protein coding genes to mRNA and others
Eukaryotic Pol III function
Transcribe tRNA and rRNA
What do all promoter regions contain in eukaryotic cells?
TATA box sequence
Location of TATA box in eukaryotic cells
-35 to -25 region upstream of transcription start site
What binds to the TATA box in eukaryotes?
TATA box binding protein (TBP) of TFIID complex
Eukaryotic transcription: General transcription factors in order of binding
TFIID, TFIIB, TFIIF, TFIIE, TFIIH
Structure of TBP
ß sheets that line up and fit in minor groove of DNA, bending the DNA structure
