Transcription Flashcards
Housekeeping gene expression
Gene is expressed in all tissues
Transcription
Gene expression
Promoter gene sequences
Control gene expression and act as the recognition site for RNA Pol
Coding gene sequences
Transcribed into mRNA
Genes
Made up of nucleotides and regulatory sequences
RNA polymerase
Copies DNA sequence from template strand to make RNA
Prokaryotic RNA polymerase
Has only 1 type and consists of 5 subunits
Sigma subunit
Recognizes promoter and dissociates after initiation
initiation complex
Made up of 10 nucleotides, its rate of formation affects the rate of transcription and it forms upon the recognition of the sigma factor
Beta prime subunit
Catalyzes the formation of a phosphodiester bond
Beta subunit
Binds DNA to the forming RNA
Elongation
Synthesizes the RNA transcript
Termination
Done by a palindromic sequence or a rho factor
Palindromic sequences
Gc rich region that folds to form a hairpin loop
Rho factor
Protein that binds to the RNA and moves along it to catch up to the polymerase to destabilize the hybrid
Eukaryotic RNA polymerase ll
Found in the nucleoplasm and transcribes mRNA
Eukaryotic RNA polymerase lll
Found in the nucleoplasm and transcribes tRNA
Rate of eukaryotic transcription
Regulated by the binding of transcription factors to specific promoter sequences
Gc box
Found in house keeping genes
Tata box
Found in tissue specific genes and it is used for specifying the start site of transcription
Ccaat box
Important for transcriptional initiation
Enhancer elements
DNA sequences that act as transcription activators required for full activity of the promoter
Types of transcription factors
Basic, promoter-specific, coactivators
RNA processing steps
mRNA capping, addition of poly A tail, RNA splicing
mRNA capping
Addition of a 7-methylguanosine to the 5’ nucleotide via a 5’-5’ triphosphate bridge by guanylyltransferase
Addition of poly A tail
Polyadenylate pol complex cleaves RNA and poly A pol adds an A tail at the 3’ end, this results in homogenous fragments of RNA
RNA splicing
The removal of introns
Spliceosome
Set of proteins and RNA where splicing happens
Eukaryotic RNA pol l
Found in the nucleolus and transcribes rRNA
