Transcription and Translation Flashcards
RNA polymerase adds NTP’s to what end?
3’ OH **Needs the 3’ OH
RNA polymerase reads DNA template strand in what direction?
3’ to 5’
RNA polymerase synthesizes in what direction?
5’ to 3’
RNA synthesis occurs where in prokaryotes?
cytoplasm
RNA synthesis occurs where in eukaryotes?
nucleus
What part of prokaryotic RNA polymerase scans DNA for promoters?
Sigma factor
What part of prokaryotic RNA polymerase actually produces RNA?
Apoenzyme (alpha and beta subunits, without sigma)
What prokaryotic RNA produces rRNA?
Pol I
What prokaryotic RNA produces mRNA?
Pol II
What prokaryotic RNA produces tRNA and other small RNAs like 5S rRNA?
Pol III
the lac operon is an example of what kind of prokaryotic gene?
Polycistronic gene: one RNA codes for more than one protein that are all apart of the same metabolic pathway
What end of Euk DNA is the promoter region found?
5’ end and is NOT transcribed
What is the intermediate RNA strand made before a mature mRNA?
hnRNA (heterogenous)
What is removed from the hnRNA that forms the mRNA?
Intron
What are the two prokaryotic promoter elements recognized by sigma factor?
Pribnow (TATAAT) box at -10
TTGACA at -35
What are the two Euk promoter elements?
Hogness (TATA) box at -25
CAAT boxes between -40 and -100
What binds to Euk promoters and must be present to initiate transcription?
TATA Binding Protein (TBP) and Transcription Factors (TFII’s)
DNA sequence that can bind to a protein factor
cis element
cis element DNA portion that lowers transcription rate
cis element (portion of DNA that increases Silencer element
Steroids bind to these elements to activate transcription
Enhancer elements
binds to silencer to lower transcription rate
Repressor
cis element portion of DNA that increases transcription
Enhancer element
Euk DNA is transcribed as this first
hsRNA
5’ cap contains what group?
methylated GTP
Is the Poly(A) tail added to the end of mRNA?
NO!
Where is the Poly(A) tail added on mRNA?
At a specific cleavage site
What performs the splicing of mRNA?
snRNPs
What base endings signal introns?
GU—AG
Where are ribosomes built?
Nucleolus
Where do small and large sub units come together?
Cytoplasm
tRNA contains what bases not found in other RNA?
Thymine and Pseudouracil
What is added to the tRNA enzymatically, which gives it the capability of carrying amino acids?
3’ CCA (Can Carry Amino acids)
Rifampin and Rifamycin bind to RNA Polymerase to prevents what?
transcription initiation
Streptolydigin binds to bacterial RNA polymerase and prevents what?
elongation
a-amanitin inhibits what?
Eukaryotic RNA Pol II and prevents mRNA synthesis
Start codon
AUG
Start codon coded AA
Methionine (Met)
Stop codons
UAG, UGA, UAA
What is located on tRNA and can bind to multiple bases?
Inosine
Change of base pair mutation
point mutation
Wrong AA coded for?
Missense
AA codon changed to a STOP codon
Nonsense (“stop the nonsense”)
Base change that specifies the same AA
Silent
What mutation usually leads to premature termination by new STOP codon in new reading frame?
Frameshift
AA binds to what on CCA end of tRNA?
Adenine
What is the reaction that attaches the AA to tRNA?
Aminoacylation
Translation starts with what AA?
Methionine
mRNA binds to 40S ribosomal subunit containing charged tRNA
Euk translation inititation
First AA in Euk translation
Methionine
Initiation factors in Euk translation
eIF’s
Kozak consensus sequence has to do with what step in translation
Euk translation initiation
Shine-Dalgarno sequence has to do with what step in Prok translation?
Prok translation initiation
mRNA binds upstream to AUG and 16S rRNA
Prok translation initiation
First AA in Prok translation
Formyl-methionine
Delivery of appropriate aminoacyl-tRNA’s are directed by what?
Elongation factors
Peptide bond formation is catalyzed by what?
Peptidyl Transferase
Peptidyl Transferase is associated with what ribosomal subunit?
Larger 50S or 60S
The A, P, and E-sites are associated with what translation step?
Elongation
Translocation occurs during what translation step?
Elongation
Termination occurs at what codon?
the STOP codons
Prok tRNA contains what group, that makes it different from euk tRNA?
Formyl group
Adding Proline or Lysine to amino acid residues to increase collagen stability is an example of what?
Post translational modification
In I-cell disease, the patient has a deficiency in what?
mannose-6-phosphate
Streptomycin binds and inhibits what?
Binds 16S rRNA of 30S subunit
Inhibits translational inititation
Tetracylcine binds and blocks what?
Binds to 30S subunit
Blocks tRNA from binding to A site
Chloramphenicol binds and blocks what?
Binds 50S subunit
Blocks peptidyltransferase activity
Erythromycin binds and inhibits what?
Binds 50S subunit
Inhibits translocation
A patient with Tay-Sachs disease has a deficiency in what enzyme?
Hexosaminidase
Tay-Sachs disease is due to what kind of mutation?
Insertion mutation
Meaning a single AA can have more than one triplet code
Degenerate
Polysomes are found where?
cytoplasm and RER