Regulation Flashcards
Gene expression
The creation of functional product
Central dogma
The process by which the instruction in DNA are converted to a functional product
Start and end product of transcription
DNA –> RNA
Start and end product of translation
RNA –> protein
General transcription factor
Identifies where transcription must begin and helps bind the RNA polymerase to that location
General transcription factor in bacteria
Sigma factor
General transcription factor in archaea
TATA binding protein
General transcription factor in eukarytoes
Numerous binding proteins
What are the small molecules that regulate transcription?
Inducers, co-repressor or co-activators
How does termination of transcription occur in bacteria?
Rho-dependent or Rho-independent
Rho-dependent
Near end of gene, Rho protein collides with polymerase and releases mRNA
Rho-independent
Near the end of the gene the mRNA folds back on itself, creating a hairpin, stopping transcription
How does termination of transcription happen in eukaryotes?
Depends on polymerase
Polyerase I
Termination sequence
Polymerase II
Cleaved during cleanup
Polymerase III
Hairpin formed
How is transcription terminated in archaea?
Not well studied
Operons
The expression of multiple genes is controlled by the same promoter and creates a single trasncript
Trp operon
Synthesizes tryptophan when it is not present in the environment
lac Operon
When lactose is present, lac operon “turns on” and helps process lactose
In E. coil if glucose is present
E. coli prefers to use glucose instead of lactose, therefore lac operon depends on concentration of glucose and lactose
Nucleosome
Histones with DNA wrapped around it
What chemical process signals histone to wind DNA more tightly?
Methylation
What chemical process signals histone to wind DNA loosely?
Acetylation
When acetylation occurs
The genes are more easily accessible for transcription
What happens before transcribed RNA can leave the nucleus
It must be porcessed
Processing includes
RNA splicing, 5’ capping, 3’ end cleaving and polyadenylation
Nuclear Pore Complex
Regulates the movement of mRNA out of the nucleus, which can happen at various rates
Which domain has simultaneous transcription and translation
Bacteria
Which domain has Shine-Dalgarno sequence in mRNA?
Bacteria
Polycistronic mRNA
When an mRNA strand codes for multiple peptides
What is the process of post-translational modification?
1) removal of translated signal sequence
2) proper “folding” of polypeptides and association of multiple polypeptide subunits
3) various chemical modification of individual amino acids
