Flashcards in Lesson 7 Transcription Deck (69)
What is the difference between a template strand and a coding strand in transcription?
The template strand is the DNA strand from which RNA is transcribed. RNA is complementary to the template strand but identical to the coding strand, which is the DNA strand opposite to the template strand.
What is the difference between the promoter, the terminator, and regulatory sequences?
The promoter is a sequence that provides a signal to begin transcription. The terminator signals the end of transcription. Regulatory sequences are involved in the regulation of gene expression.
In bacteria, what is the ribosomal binding site, AKA Shine-Dalgarno sequence?
This sequence provides a location for the ribosomes to recognize and begin the process of translation.
What are codons? What are the start and stop codon?
A codon is a sequence of three nucleotides. A start codon is the first codon, and it is very close to the initiation site of translation. A stop codon signals the end of translation.
What are the three stages of transcription?
Initiation, elongation, in which the RNA transcript is synthesized, and termination.
What happens during transcription initiation?
The promoter functions as a recognition site for transcription factors. The transcription factors enable RNA polymerase to bind to the promoter. Following binding, the DNA is dentures into a bubble known as the open complex.
What is the DNA open complex?
A bubble into which DNA is dentures once RNA polymerase has bound to the promoter.
What happens during transcription elongation?
RNA polymerase slides along the DNA in an open complex to synthesize RNA.
What happens during termination?
A termination signal is reached that causes RNA polymerase and the RNA transcript to dissociate from the DNA.
What recognizes the sequences of bases within the promoter region?
Proteins known as transcription factors
What are structural genes?
Genes that encode an RNA transcript known as mRNA.
What is tRNA?
Transfer RNA. It is necessary for the translation of mRNA.
What is rRNA?
Ribosomal RNA. It is necessary for the translation of mRNA. rRNAs are components of ribosomes that are composed of both rRNAs and protein subunits.
What is 7S RNA?
Found in eukaryotes. Necessary in the targeting of proteins to the endoplasmic reticulum. It is a component of a complex known as signal recognition particle (SRP), which is composed of 7S RNA and six different protein subunits.
What is scRNA?
Small cytoplasmic RNA. Found in bacteria. Its sequence is similar to 7S RNA found in eukaryotes. ScRNA is needed for protein secretion.
What is RNA of RNaseP?
RNaseP is an enzyme that is necessary in the processing of all bacterial tRNA molecules. The RNA is the catalytic component of this enzyme.
What is snRNA?
Small nuclear RNA (snRNA) is necessary in the splicing of eukaryotic pre-mRNA. SnRNAs are components of a spliceosome, which is composed of both snRNAs and protein subunits.
What is snoRNA?
Small nucleolar RNA is necessary in the processing of eukaryotic rRNA transcripts. SnoRNAs are also associated with protein subunits. In eukaryotes, snoRNAs are found in the nucleolus where rRNA processing and ribosomes assembly occur.
What are viral RNAs?
Some types of viruses use RNA as their genome, which is packaged within the viral capsid.
In bacteria, what is the -35 sequence? The -10 sequence?
The -35 sequence is a recognition sequence and the -10 sequence is the site where the two DNA strands will separate when transcription begins. Both sequences are in the promoter region.
What is the consensus sequence?
The most common promoter sequence.
When is bacterial transcription initiated?
Bacterial transcription is initiated when RNA polymerase holoenzyme binds at a promoter sequence.
What is bacterial RNA polymerase composed of?
Bacterial RNA polymerase is composed of a core enzyme plus a subunit called sigma factor.
What is the role of sigma factor in bacterial RNA polymerase?
Sigma factor recognizes the promoter and initiates transcription.
What is the role of the core enzyme in bacterial RNA polymerase?
The core enzyme catalyzes the synthesis of an RNA strand.
What happens to sigma factor once the -10 region has been unwound during transcription initiation?
The sigma factor dissociate from the holoenzyme.
In what direction is RNA synthesized during transcription? What is used as a precursor?
The RNA is synthesized in a 5' to 3' direction using ribonucleoside triphosphate as precursors.
What substance is released by ribosome during transcription?
Pyrophosphate is released by the ribosomes during transcription.
How do nucleotides enter ribosome to elongate RNA? Where are the nucleotides added?
Nucleotides diffuse through a pore in the enzyme and are attached at the 3' end of the growing RNA transcript.