Transcription
Name the 3 stages of Transcription
Initiation
Elongation
Termination
What is the purpose of 5 capping in mRNA?
Regulation of nuclear export; Prevention of degradation by exonucleases; Promotion of translation
What bacterial regulator turns off the production of the proteins responsible for lactose metabolism when this sugar is absent from the medium?
Lac repressor
What are three consecutive nucleotides in RNA that specifies either one amino acid or a stop to the translation process?
Codon
a specific DNA sequence that directs RNA polymerase to bind to DNA, to open the DNA double helix, and to begin synthesizing an RNA molecule.
promoter
During initiation where does the RNA polymerase bind to start transcription?
Promoter sequence (TATA box)
What is the purpose of the Poly-A-tail?
poly(A) tail protects the mRNA molecule from enzymatic degradation in the cytoplasm and aids in transcription termination, export of the mRNA from the nucleus, and translation.
lactose (lac) operon includes
Three adjacent genes for lactose utilization enzymes
Promoter sequence where RNA polymerase binds
Operator sequence is where a repressor can bind and block RNA polymerase action
What is a set of three consecutive nucleotides that pairs with the complementary codon in an mRNA molecule?
Anti-codon
An enzyme that catalyzes the formation of the phosphodiester bonds that link the nucleotides together to form a linear chain
RNA polymerase
What type of RNA is formed during transcription?
During 5 capping what enzyme removes a phosphate from the 5’ end of the nascent RNA?
Phospatase
What is a repressor operon? example?
It prevents transcription; Trp Operon
What is the purpose of wobble base pairing?
to allow multiple codons to code for a single amino acid.
Transcribed segment of DNA that carries the information of just one gene, and codes for either a single RNA molecule or a single protein
Transcription Unit.
RNA polymerases I and III transcribe the genes encoding for what 3 RNA's?
transfer RNA, ribosomal RNA, and various small RNAs.
A spliceosome is composed of what?
snRNAs (small nuclear RNAs), named U1, U2, U4, U5, and U6.
In the presence of what does the Lac repressor bind to the operator that causes no transcription of the Lac operon
Glucose
To maintain the correct reading frame and to ensure accuracy, protein synthesis is performed in the
Ribosome
a segment of DNA that encodes for the formation of a specific polypeptide chain; a structural gene.
Cistrons
What are the 3 modifications in Eukaryotic Pre-mRNA?
5 capping, RNA splicing, & polyadenation
The lariat during mRNA splicing is caused when?
When the 5' splice site binds to the branchpoint in the excised intron sequence.
Switching devices in all cells for gene regulation are composed of what?
(1) short stretches of DNA of defined sequence
(2) gene regulatory proteins that recognize and bind to this DNA.
What does the E, P, and A site in tRNA stand for?
Exit site; Peptidyl-site, Aminoacyl site
a set of two or more adjacent cistrons whose transcription is under the coordinated control of a promoter, an operator, and a regulator gene.
Operon