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Questions and Answers
What function do constitutive gene products perform?
What function do constitutive gene products perform?
- Regulation of cell division
- Housekeeping (correct)
- Pathogen defense
- Signal transduction
Which of the following molecules is involved in protein synthesis and is a product of constitutive genes?
Which of the following molecules is involved in protein synthesis and is a product of constitutive genes?
- Hemoglobin
- Insulin
- rRNA (correct)
- Antibodies
In what kind of cells are the genes for constitutive gene products continuously expressed?
In what kind of cells are the genes for constitutive gene products continuously expressed?
- Only in liver cells
- Only in nerve cells
- Most cells (correct)
- Only in immune cells
Which of the following is NOT an example of a molecule produced by constitutive genes?
Which of the following is NOT an example of a molecule produced by constitutive genes?
Why are constitutive genes important in cells?
Why are constitutive genes important in cells?
What is a positive method of regulating transcription initiation?
What is a positive method of regulating transcription initiation?
Which method impedes transcription initiation?
Which method impedes transcription initiation?
Alteration in RNA Polymerase-promoter interaction can be:
Alteration in RNA Polymerase-promoter interaction can be:
What role do activators play in transcription initiation?
What role do activators play in transcription initiation?
Which factor negatively affects RNA Polymerase function?
Which factor negatively affects RNA Polymerase function?
Which process directly follows the transcription of a gene?
Which process directly follows the transcription of a gene?
At which stage is the mRNA translated into a protein?
At which stage is the mRNA translated into a protein?
What controls the amount of primary RNA transcript made?
What controls the amount of primary RNA transcript made?
Modifications made to the primary transcript to become mature mRNA is known as what?
Modifications made to the primary transcript to become mature mRNA is known as what?
Which process describes the targeting of the protein to its location?
Which process describes the targeting of the protein to its location?
Which is a control level that affects the intrinsic activity of a protein?
Which is a control level that affects the intrinsic activity of a protein?
What is the composition of the E. coli RNA Polymerase core enzyme?
What is the composition of the E. coli RNA Polymerase core enzyme?
What function does the β subunit of E. coli RNA Polymerase serve?
What function does the β subunit of E. coli RNA Polymerase serve?
Which subunit of the E. coli RNA Polymerase is NOT part of the core enzyme?
Which subunit of the E. coli RNA Polymerase is NOT part of the core enzyme?
Which function pertains to the σ subunit of E. coli RNA Polymerase?
Which function pertains to the σ subunit of E. coli RNA Polymerase?
What is the function of the α subunit in E. coli RNA Polymerase?
What is the function of the α subunit in E. coli RNA Polymerase?
Which component of RNA Polymerase is responsible for recognizing different classes of promoters?
Which component of RNA Polymerase is responsible for recognizing different classes of promoters?
What role do transcription factors play in bacterial transcription regulation?
What role do transcription factors play in bacterial transcription regulation?
How can transcription factors alter their affinity toward DNA?
How can transcription factors alter their affinity toward DNA?
What is the main effect of different sigma factors on gene expression in bacteria?
What is the main effect of different sigma factors on gene expression in bacteria?
What is the consequence of post-translational modification of transcription factors?
What is the consequence of post-translational modification of transcription factors?
Where are the skin cells of the adult frog cultured?
Where are the skin cells of the adult frog cultured?
What destroys the nucleus of the unfertilized egg?
What destroys the nucleus of the unfertilized egg?
What is injected into the enucleated egg?
What is injected into the enucleated egg?
What develops after the nucleus is injected into the enucleated egg?
What develops after the nucleus is injected into the enucleated egg?
What is the final stage in the sequence shown in the diagram?
What is the final stage in the sequence shown in the diagram?
What is the primary condition under which certain gene products are needed for cell growth?
What is the primary condition under which certain gene products are needed for cell growth?
What controls the synthesis of gene products needed only under certain conditions?
What controls the synthesis of gene products needed only under certain conditions?
What happens when ethanol is consumed concerning alcohol dehydrogenase?
What happens when ethanol is consumed concerning alcohol dehydrogenase?
Which statement correctly describes the role of alcohol dehydrogenase when ethanol is not consumed?
Which statement correctly describes the role of alcohol dehydrogenase when ethanol is not consumed?
Which scenario leads to the production of alcohol dehydrogenase?
Which scenario leads to the production of alcohol dehydrogenase?
Which region of bacterial promoters is also known as the Pribnow box?
Which region of bacterial promoters is also known as the Pribnow box?
What is the function of the UP element in some bacterial promoters?
What is the function of the UP element in some bacterial promoters?
What sequence is found at the -35 region in bacterial DNA?
What sequence is found at the -35 region in bacterial DNA?
What does the σ factor of RNA polymerase interact with?
What does the σ factor of RNA polymerase interact with?
What is the primary role of bacterial promoters?
What is the primary role of bacterial promoters?
Which of the following describes the initial control point for regulating the amount of a protein in the cell?
Which of the following describes the initial control point for regulating the amount of a protein in the cell?
What process is involved in converting pre-mRNA into mature mRNA?
What process is involved in converting pre-mRNA into mature mRNA?
Which level of control affects how much protein is synthesized from mRNA?
Which level of control affects how much protein is synthesized from mRNA?
Which process ensures that proteins reach their correct location within the cell?
Which process ensures that proteins reach their correct location within the cell?
At which point can the intrinsic activity of a protein be altered?
At which point can the intrinsic activity of a protein be altered?
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Study Notes
Constitutive Genes
- Essential components of almost all living cells, performing a "housekeeping" function
- Examples: molecules involved in protein synthesis (rRNA, tRNA, RNA polymerase subunits, etc.)
Gene Expression Regulation
- Cells can change the expression of genes
- Example: nucleus of an adult skin cell can be transferred into an enucleated egg to produce a normal tadpole
Regulation at Transcription Initiation
- (+) Alter specificity of RNA Polymerase-promoter interaction
- (-) Impede access of RNA Polymerase to its promoter
- (+) Use of activators to enhance polymerase-promoter activity
Inducible and Repressible Genes
- Gene products needed for cell growth only under certain environmental conditions
- Example: alcohol dehydrogenase (synthesized only in response to ethanol)
Levels of Control of a Protein's Amount and/or Activity
- Amount of primary RNA transcript made
- Processing of pre-mRNA into mRNA
- Rate of degradation of the mRNA
- Amount of protein made from the mRNA
- Alteration of the intrinsic activity of the protein
- Efficiency of targeting of the protein to its location
- Rate of degradation of the protein
E. coli RNA Polymerase
- Core enzyme: α₂ β β΄ω
- Holoenzyme: α₂ β β΄ ωσ
- Functions of subunits:
- α: assembly of the tetrameric core
- β: ribonucleoside triphosphate binding site
- β': DNA template binding region
- σ: initiation of transcription
Mechanisms to Regulate Transcription in Bacteria
- Use of different σ factors in RNA Polymerase
- Binding of transcription factors to promoters
- Recognition of promoters of specific genes
- Binding of small signaling molecules and post-translational modifications
DNA Sequences Involved in Regulation of Gene Expression
- Conserved -10 region (Pribnow box) and -35 region in most bacterial promoters
- Interact with σ factor of RNA polymerase
- Upstream element interacts with α subunit of RNA polymerase
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