L7 Flashcards
1
Q
Genomic Traffic Lights
A
- All cels of a given organism have the exact same genome
- Not all proteins are required all the time, in all cell types
2
Q
Gene regulation mechanisms:
A
- Ensure that cells do not express all the genes of their genome in a constitutive manner, but rather based on need
- The need for a gene or set of gene to be turned on depends on factors such as: housekeeping, environment, tissue-specific functions, and development phases
3
Q
Gene regulation:
A
Regulation of the synthesis of a gene transcript and final protein product via:
- Modulation of DNA transcription into RNA
- Modulation of mRNA stability
- Modulation of mRNA translation into protein
- Post-translational modifications
4
Q
Gene regulation in prokaryotes
A
- Nutritional opportunities are the main reason for gene regulation in bacteria
5
Q
Bacteria need to be able to:
A
- Recognize environmental conditions that would lead to differential gene expression
- Respond by turning on or off the transcription of each genes, or a group of genes
6
Q
Regulatory components of the lac operon:
A
- lac protomer site (P): RNA polymerase binding site
2. lac operator site (O): lac repressor binding site
7
Q
Negative regulation of the lac operon
A
- Binding of the “repressor” to the “operator” prevents gene transcription by RNA polymerase
- The DNA binding site of repressor is only functional when its allosteric site is free of the effector
- The repressor prevents the expression of the lac operon when lactose is absent
8
Q
When lactose is present:
A
- Binding of the repressor to allolactose changes its 3D structure
- The repressors can no longer bind the operator
- RNA polymerase can transcribe the 3 structural genes
9
Q
How can we measure the expression of the operon?
A
- RT-qPCR
- Western blotting
- By measuring the product of lactose breakdown by beta-galactosidase
10
Q
Molecular characterization of the operon
A
- Structural genes: Z, Y
- Operator
- Gene 1 (repressor)
- Promoter
