Regulation of Gene Expression Flashcards
(23 cards)
Bacteria can respond to environmental change by
*Regulating protein activity
*Regulating protein production
An operon in bacteria is a stretch of DNA that includes
*Promoter
*Operator
*The genes that they control
Operator
DNA within promoter that acts as a regulatory “switch”
Negative gene regulation
What is the involvement of a repressor
*Repressible operons
*Inducible operons
Repressible Operon
A repressible operon is usually on; binding of a repressor to the operon shuts off transcription
Positive gene regulation
Some operons are also subject to positive control
If lactose is present and glucose is scarce with cAMP level high what are the results?
Abundant lac mRNA synthesized
If lactose is present and glucose is present with cAMP level low what are the results?
Little lac mRNA synthesized
What is CAP
catabolite activator protein
Combined negative and positive regulation in E.coli
*lac repressor acts as on/off switch
*CAP acts as volume control
All organisms must regulate which _____ are expressed at any given time
Genes
In multicellular organisms what is essential for cell specialization?
Gene expression
True or false
Eukaryotic gene expression can be regulated only at certain stages.
False
It can be regulated at every stage.
Are cells in an organism genetically identical?
Yes
Differences between cell types result from what?
Differential gene expression
What does acetylation of histone tails promote?
Loose chromatin structure that permits transcription.
Do histone tails protrude inward or outward from a nucleosome?
Outward
Epigenetic Inheritance
The inheritance of traits transmitted by mechanisms not directly involving the nucleotide sequence.
Chromatin Modifications
*Do not alter DNA sequence
*….but may be passed to future generations of cells
Control Elements
Segments of noncoding DNA that help regulate transcription by binding certain proteins.
True or False
Control elements are critical to the precise regulation of gene expression in different cell types.
True
Does RNA polymerase require general transcription factors to initiate transcription in eukaryotes
Yes
What do high levels of transcription of particular genes depend on?
Specific transcription factors
