Week 8 Flashcards
Repressor
Binds to operator and blocks RNA polymerase from transcribing gene
Operator
Site for repressor to bind to
Regulatory gene
constitutive expression, not a part of operon… but produces repressor
Promotor
DNA sequence that indicates to RNA polymerase where to begin transcription
I- mutation effect
Doesn’t produce working repressors, so constitutive expression
Oc mutation effect
Doesn’t allow repressor to bind to operator, constitutive expression
Is mutation effect
Super repressor, inducer cannot bind, no expression
Order to determine effect of lac operon mutations
Promoter, Repressor, Operator, Permease, B-gal
Constitutive expression
Always produced
Cis-acting elements
Affection regulation of genes on the same DNA only
Trans-acting elements
Can affect regulation of different DNAs (proteins)
Transformation
How bacteria can take up small bits of DNA
Core Promoters
An area close to the coding region, and maintains basal level of transcription (TATA box)
Enhancers
Boost gene expression by binding to transcription factors (which interact with the promoter and RNA polymerase)
- Can be located either up or downstream
Silencers
Restrict transcription
Euchromatin
Lightly packed areas of the chromosome (ends), usually more transcription occurs
Heterochromatin
Condensed areas of the chromosome (closer to the centre), less transcription occurs
Transcription factors
Have specific motifs, contain activator dimers
Activator dimers
Can bind to DNA palindromes (enhancers)
Transcriptional repressors
- Can bind to DNA silencers, DNA enhancers, activators
- Can bind to the basal complex and prevent it from binding to promoter
- Can induce wrapping of DNA
- Recruits corepressors
How is gene expression controlled?
Chromatin structure, DNA methylation patterns
How does chromatin structure control gene expression?
By modifying histones
- Acetylation
- Methylation
Remodeling (removing histones)
DNA methylation patterns
Silence genes, by methylating promoter’s CpG-rich sequence
Epigenetics
The study of changes in gene expression that is not related to sequence changes
