BIO 235 Exam 4 Questions and
Answers 100% Pass
Induction (gene regulation) example in E. coli - ✔✔E. coli digests lactose
but does not have many genes that incorporate lactose into the
environment bc there is not a lot of lactose
When enzymes break down lactose, they signal the cell to express more
genes that express the enzymes and permeases for the gene
The more lactose you have, the more the genes will express
Eventually, it will break down all of the lactose to the point where the cell
no longer expresses the genes to break down lactose
Operon theory - ✔✔one signal can simultaneously regulate expression of
several clustered genes
1
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,Lactose operon in E. coli - ✔✔Structural genes (lacZ, lacY, lacA) -
something that does something
Promoter - site of which RNA polymerase binds
Operator - controls transcription initiation
Repressor - binds to operator (encoded by lacI gene, Trans-acting)
Inducer - prevents repressor from binding to operator
Negative regulator - ✔✔protein that prevents transcription
Repression of lac gene expression - ✔✔lacI repressor gene makes repressor
protein, which binds to the operator to stop transcription
When it binds to the operator, it is turned off and no transcription occurs
regulatory elements - ✔✔short DNA sequences that affect the binding of
RNA polymerase to the promoter
operator
How does the presence of lactose affect repressor protein? - ✔✔When
lactose is presence, allolactose (inducer) is made, which binds to the
2
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, repressor. This changes its shape and prevents it from binding to the
operator. RNA polymerase is able to bind to the promoter and initiate
transcription.
Allosteric protein - ✔✔Protein that changes its conformation on binding
with another molecule.
constitutive expression - ✔✔gene product made continuously
constitutive mutants - ✔✔express the enzymes in the absence and presence
of inducer
lacI- mutant - ✔✔lac genes are expressed in the absence and the presence of
the inducer
The mutant repressor cannot bind to the operator, so enzymes are
produced constitutively
lacIs mutants - ✔✔superrepressor binds to operator but cannot bind to the
inducer
repressor binds to operon, even when inducers are present
lac repressor domains - ✔✔DNA-binding domain
3
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Answers 100% Pass
Induction (gene regulation) example in E. coli - ✔✔E. coli digests lactose
but does not have many genes that incorporate lactose into the
environment bc there is not a lot of lactose
When enzymes break down lactose, they signal the cell to express more
genes that express the enzymes and permeases for the gene
The more lactose you have, the more the genes will express
Eventually, it will break down all of the lactose to the point where the cell
no longer expresses the genes to break down lactose
Operon theory - ✔✔one signal can simultaneously regulate expression of
several clustered genes
1
100% Pass Guarantee Katelyn Whitman, All Rights
,Lactose operon in E. coli - ✔✔Structural genes (lacZ, lacY, lacA) -
something that does something
Promoter - site of which RNA polymerase binds
Operator - controls transcription initiation
Repressor - binds to operator (encoded by lacI gene, Trans-acting)
Inducer - prevents repressor from binding to operator
Negative regulator - ✔✔protein that prevents transcription
Repression of lac gene expression - ✔✔lacI repressor gene makes repressor
protein, which binds to the operator to stop transcription
When it binds to the operator, it is turned off and no transcription occurs
regulatory elements - ✔✔short DNA sequences that affect the binding of
RNA polymerase to the promoter
operator
How does the presence of lactose affect repressor protein? - ✔✔When
lactose is presence, allolactose (inducer) is made, which binds to the
2
100% Pass Guarantee Katelyn Whitman, All Rights
, repressor. This changes its shape and prevents it from binding to the
operator. RNA polymerase is able to bind to the promoter and initiate
transcription.
Allosteric protein - ✔✔Protein that changes its conformation on binding
with another molecule.
constitutive expression - ✔✔gene product made continuously
constitutive mutants - ✔✔express the enzymes in the absence and presence
of inducer
lacI- mutant - ✔✔lac genes are expressed in the absence and the presence of
the inducer
The mutant repressor cannot bind to the operator, so enzymes are
produced constitutively
lacIs mutants - ✔✔superrepressor binds to operator but cannot bind to the
inducer
repressor binds to operon, even when inducers are present
lac repressor domains - ✔✔DNA-binding domain
3
100% Pass Guarantee Katelyn Whitman, All Rights
