Transcriptional circuits in prokaryotes and eukaryotes Flashcards
What is a transcriptome?
Segment which is transcribed is known as the transcriptome
What percentage of the prokaryotic genome is transcribed?
Only about 50%
What amount of the transcribed at any one time?
Only a fraction
What is an abundant transcript?
type of gene gives rise to many copies of RNA
What is a rare transcript?
where not as many RNA copies are produced
What is a no transcript and example?
type of gene has no transcript in some type of cells like beta globin genes which are only expressed in red blood cells
What are inducible genes?
Where transcription is induced by a stimuli
What does the stimulation of an inducible gene result in?
This results in a gene which is a rare or no transcript to become an abundant transcript
What is a promoter region?
Recruit RNA polymerase to a DNA template
How many directions does RNA polymerase move in?
RNA polymerase only moves in one direcrion
What are enhancers?
DNA sequences which increase transcription
Where do enhancers reside?
Can reside 5’ or 3’ to a transcription unit and also found in introns
What do enhancers contain?
Contain DNA sequences which contain very strong binding sites for transcription factors
Where are enhancers located in terms of the transcription site?
Not immediately adjacent to the site of transcription
What do RNA polymerase do along the complex?
RNA polymerase slides along the duplex without being able to efficiently recognise promoters
What factors allow the recognition of promoter in prokaryotes?
Sigma factors
What factors allow the recognition of promoter in eukaryotes?
TFII basal transcriptional machinery
What happens once RNA polymerase binds to DNA?
Once RNA polymerase binds to DNA, converted from a closed to an open compound
What do sigma factors do?
Sigma factors recognises the -35 and -10 motifs common to prokaryotes and enables RNA polymerase to make stable contact with DNA
What is a consensus sequence?
DNA having similar structure and function in different organisms
How is the consensus sequence determined?
Determined by aligning many nucleotide sequences that share a common function then determining the most commonly expressed nucleotide at each position
Why is the TATA box needed
TATA box is needed to recruit general transcription factors and then RNA polymerase
What happens to the Lac operon when there are low levels of glucose?
§ CAP protein binds to the promoter region under low glucose level and RNA polymerase binds to the promoter region
□ Lactose will bind to the LAC repressor and RNA polymerase will transcribe the LAC ZYA gene.
RNA formed translated into proteins which utilise energy from Lactose
What happens to the Lac operon when theres sufficient amount of glucose?
LAC repressor binds to promoter region when there’s sufficient amount of glucose
This prevents transcription
