GCD 3022 Ch 14-16,19| Ques ons and answers |
Updated RATED A+ | NEW 2026
gene regula on
the level of gene expression can vary under different condi ons
cons tu ve genes
genes that are expressed all the me
main benefit of regula ng genes
encoded proteins will be expressed only when required
repressors
bind to DNA and inhibit transcrip on (nega ve control)
ac vators
bind to DNA and increase transcrip on (posi ve control)
small effector molecules
regulate gene transcrip on by binding a regulatory protein (inducer, inhibitor, corepressor)
repressor + inducer
transcrip on occurs
ac vator + inducer
transcrip on occurs
repressor + corepressor
transcrip on does not occur
ac vator + inhibitor
transcrip on does not occur
enzyme adapta on
the phenomenon in which a par cular enzyme appears within a living cell a$er the cell has
been exposed to the substrate for that enzyme
operon
, group of genes opera ng together
polycistronic mRNA
molecules of mRNA that code for mul ple proteins
lac operon
a gene system whose operator gene and three structural genes control lactose metabolism in E.
coli
Jacob and Monod Experiment to study lac operon
Hypothesized that a mutant lacl- gene results in (1) the synthesis of an internal inducer or (2)
eliminates the func on of a lac repressor
Used bacterial conjuga on to study different por on of the lac operon
Iden fied F' factors (plasmids) that carried por ons of the lac operon aka merozygotes (par al
diploids)
Discovered hypothesis 2 was correct and that the repressor from the F' factor can diffuse and
turn off the lac operon on the bacterial chromosome
trans-effect
form of gene regula on that can occur even though two DNA segments are not physically
adjacent
cis-effect
form of gene regula on where DNA must be adjacent to the genes it regulates
catabolite repression of the lac operon
E. coli prefers to use glucose as its carbon source so it represses the lac operon because its is a
waster of energy to make product and then use glucose instead
diauxic growth
the sequen al use of two sugars by a bacterium
trp operon
Involved in the biosynthesis of the amino acid tryptophan
these genes encode enzymes involved in tryptophan biosynthesis
Updated RATED A+ | NEW 2026
gene regula on
the level of gene expression can vary under different condi ons
cons tu ve genes
genes that are expressed all the me
main benefit of regula ng genes
encoded proteins will be expressed only when required
repressors
bind to DNA and inhibit transcrip on (nega ve control)
ac vators
bind to DNA and increase transcrip on (posi ve control)
small effector molecules
regulate gene transcrip on by binding a regulatory protein (inducer, inhibitor, corepressor)
repressor + inducer
transcrip on occurs
ac vator + inducer
transcrip on occurs
repressor + corepressor
transcrip on does not occur
ac vator + inhibitor
transcrip on does not occur
enzyme adapta on
the phenomenon in which a par cular enzyme appears within a living cell a$er the cell has
been exposed to the substrate for that enzyme
operon
, group of genes opera ng together
polycistronic mRNA
molecules of mRNA that code for mul ple proteins
lac operon
a gene system whose operator gene and three structural genes control lactose metabolism in E.
coli
Jacob and Monod Experiment to study lac operon
Hypothesized that a mutant lacl- gene results in (1) the synthesis of an internal inducer or (2)
eliminates the func on of a lac repressor
Used bacterial conjuga on to study different por on of the lac operon
Iden fied F' factors (plasmids) that carried por ons of the lac operon aka merozygotes (par al
diploids)
Discovered hypothesis 2 was correct and that the repressor from the F' factor can diffuse and
turn off the lac operon on the bacterial chromosome
trans-effect
form of gene regula on that can occur even though two DNA segments are not physically
adjacent
cis-effect
form of gene regula on where DNA must be adjacent to the genes it regulates
catabolite repression of the lac operon
E. coli prefers to use glucose as its carbon source so it represses the lac operon because its is a
waster of energy to make product and then use glucose instead
diauxic growth
the sequen al use of two sugars by a bacterium
trp operon
Involved in the biosynthesis of the amino acid tryptophan
these genes encode enzymes involved in tryptophan biosynthesis
