Chapter 8 Flashcards
Transcription
Copying of DNA into RNA
Cell accesses it’s data in genome via…
Transcription
RNA is based off _______ DNA strand
Complementary strand
Define holoenzyme
Holo means all inclusive
Consists of core polymerase and sigma factor required for initiation
What process needs polymerase?
Required for elongation
What process requires sigma factors?
Initiation
What do sigma factors and RNA polymerase do?
They bind and guide RNA to specific DNA sequences called promoters
What do you call a sigma factor that is made in large quantities and used all the time?
Housekeeping sigma factor
Consensus sequence
DNA sequence similarities among different promoters recognized by the sigma factor
Consists lf most likely base of each position of predicted promoter
Three stages of transcription
Initiation, elongation, termination
Describe initiation ( transcription)
Sigma factor of holoenzyme binds promoter to dna
Promoter unwinds one helical turn
RNA polymerase binds
Open complex form of RNA polymerase begins transcription
Describe elongation ( transcription)
RNA chin is extended by sequential addition of ribonucleotides from nucleoside triphosphate
Sigma dissociates after 9 bases
Original RNA polymerase continues along template
Unwinding makes 17 bp bubble
Positive supercoils upstream are removed by DNA topoisomerase
Describe termination (transcription)
RNA pol detached from DNA
Rho dependent termination
Relies on rho protein and a strong pause site at 3’ end
Rho independent
Requires GC rich region that causes RNA stem and loop to form and causes RNA pol to pause
Rifamycin
Selectively binds to bacterial RNA pol and blocks RNA from leaving RNA polymerase, inhibits transcription initiation
Actomycin
Intercalated between GC base pairs and mimics and DNA base
Inhibits transcription elongation
Not selective for proks
tmRNA
Free ribosome stuck on damaged mRNA and has properties of tRNA and mRNA
Catalytic RNA
Associate with some protein to provide catalytic activity
Nick name for third base
The wobble base
Bacteria ribosome subunits
60 and 40 to make 80
Three binding sites on ribosome and describe
A-acceptor site, binds incoming aminoacyl tRNA
P-peptidyl tRNA site, harbors tRNA with the growin polypeptide chain
E-exit site, binds a tRNA recently stripped of proteins
Peptidyl transferase and shine-dalgarno
Peptidyl transferase enzyme activity forms peptide binds between amino acids
Shine dalgarno sequence binds to rRNA and positions the start codon in the p site
Examples of antibiotics
Streptomycin, tetracycline, erythromycin
What antibiotics present translocation
Erythromycin, fusidic acid
What removes N-formylmethione?
Methionyl aminopeptidase
Degron
Dragon They degraded(aka destroy)'proteins
Proteases
Destroy proteins
Srp
Signal recognition particle
Helps proteins get inserted in the membrane
SecYEG translocon
Moves unfolded proteins to where chaperones will take over
Twin Argonne translocase
Moves folded proteins across inner membrane
Type 1 protein secretion
Moves certain proteins directly from the cytoplasm to extra cellular matrix
Which is harder to sequence, euks or proks?
Euks due to introns and exon
Orthologous
Identical function, different organisms
Paralogous
Slightly different functions in cell
