MBIO 3401 TTU Exam 2 Fall 2023
Save
help a cell sense internal changes and alter its gene
Regulatory proteins
expression to match.
- Repressors (negative control)
There are 2 forms of
regulatory proteins:
- Activators (positive control)
bind to regulatory sequences in the DNA and prevent
transcription of target genes.
Repressors
- some must first bind a small ligand.
bind to regulatory sequences in the DNA and
stimulate transcription of target genes.
Activators
- most must first bind a small ligand.
- Alterations of DNA sequence
- Control of transcription
Microbes control gene
expressions at several - Control of mRNA stability
levels
- Translational control
- Post-translational control
, Scientist Jacques Monod and Francois Jacob - genes
could be regulated.
Paradigm of the Lactose
E. coli, enzymes used to metabolize lactose were
Operon
inducible, glucose were constitutive.
- 1965 nobel prize for his study of phage nysogeny.
LacZYA operna E. coli was 1st gene regulatory system described.
Organization of LacZYA
Opepn
LacI binds as a tetramer to operator region.
If lactose is absent then
- represses the lac operon by preventing open
complex formation by RNA ploymerase.
B-galactosidase (LacZ) at low levels, cleaves and
rearranges lactose to make inducer allolactose.
If lactose is present then
- Allolactose binds to LacI, reducing affinity to
operator allowing induction of operon.
cAMP and cAMP receptor are required for the maximum expression of the lac
protein (CRP) operon.
operon enabling catabolism of one nutrient is
Catabolite repression repressed by the presence of a more favorable
nutrient.
the biphasic curve if a culture growing in 2 carbon
Diauxic growth
soruces.
Save
help a cell sense internal changes and alter its gene
Regulatory proteins
expression to match.
- Repressors (negative control)
There are 2 forms of
regulatory proteins:
- Activators (positive control)
bind to regulatory sequences in the DNA and prevent
transcription of target genes.
Repressors
- some must first bind a small ligand.
bind to regulatory sequences in the DNA and
stimulate transcription of target genes.
Activators
- most must first bind a small ligand.
- Alterations of DNA sequence
- Control of transcription
Microbes control gene
expressions at several - Control of mRNA stability
levels
- Translational control
- Post-translational control
, Scientist Jacques Monod and Francois Jacob - genes
could be regulated.
Paradigm of the Lactose
E. coli, enzymes used to metabolize lactose were
Operon
inducible, glucose were constitutive.
- 1965 nobel prize for his study of phage nysogeny.
LacZYA operna E. coli was 1st gene regulatory system described.
Organization of LacZYA
Opepn
LacI binds as a tetramer to operator region.
If lactose is absent then
- represses the lac operon by preventing open
complex formation by RNA ploymerase.
B-galactosidase (LacZ) at low levels, cleaves and
rearranges lactose to make inducer allolactose.
If lactose is present then
- Allolactose binds to LacI, reducing affinity to
operator allowing induction of operon.
cAMP and cAMP receptor are required for the maximum expression of the lac
protein (CRP) operon.
operon enabling catabolism of one nutrient is
Catabolite repression repressed by the presence of a more favorable
nutrient.
the biphasic curve if a culture growing in 2 carbon
Diauxic growth
soruces.
