Podcast
Questions and Answers
Why are all genes not 'on' all the time in E. coli?
Why are all genes not 'on' all the time in E. coli?
The E. coli turns on the genes only when it needs enzymes to produce the amino acid tryptophan, and since it does not need this all the time, it turns off the genes to save energy and not overproduce tryptophan.
What are the two main ways of controlling metabolism in bacterial cells?
What are the two main ways of controlling metabolism in bacterial cells?
Gene regulation and enzyme regulation
Is feedback inhibition in E. coli regulating tryptophan synthesis positive or negative inhibition?
Is feedback inhibition in E. coli regulating tryptophan synthesis positive or negative inhibition?
Negative inhibition
What is a promoter?
What is a promoter?
What is the operator and what does it do?
What is the operator and what does it do?
What is an operon?
What is an operon?
List the three components of an operon and explain the role of each one.
List the three components of an operon and explain the role of each one.
How does a repressor protein work?
How does a repressor protein work?
What are regulatory genes?
What are regulatory genes?
Distinguish between inducible and repressible operons and provide one example of each.
Distinguish between inducible and repressible operons and provide one example of each.
What is a corepressor? Give an example.
What is a corepressor? Give an example.
What is CAP and how does it work?
What is CAP and how does it work?
Explain why CAP binding and stimulation of gene expression is positive regulation.
Explain why CAP binding and stimulation of gene expression is positive regulation.
Describe the relationship between glucose supply, cAMP, and CAP.
Describe the relationship between glucose supply, cAMP, and CAP.
How can both repressible and inducible operons be negative regulators?
How can both repressible and inducible operons be negative regulators?
What does beta-galactosidase do?
What does beta-galactosidase do?
What does differential gene expression mean?
What does differential gene expression mean?
What percentage of the genes of a typical human cell is expressed at any given time?
What percentage of the genes of a typical human cell is expressed at any given time?
What is the common control point of gene expression for all organisms?
What is the common control point of gene expression for all organisms?
Distinguish between heterochromatin and euchromatin.
Distinguish between heterochromatin and euchromatin.
What occurs in histone acetylation and how does it affect gene expression?
What occurs in histone acetylation and how does it affect gene expression?
What is DNA methylation and what role may it play in gene expression?
What is DNA methylation and what role may it play in gene expression?
Where can DNA methylation be found and how can it be reversed?
Where can DNA methylation be found and how can it be reversed?
What is the result of heavy methylation of the inactive mammalian X chromosome?
What is the result of heavy methylation of the inactive mammalian X chromosome?
What is genomic imprinting and how is it maintained?
What is genomic imprinting and how is it maintained?
What is epigenetic inheritance?
What is epigenetic inheritance?
How do enhancers and activators interact with transcription factors to affect gene expression?
How do enhancers and activators interact with transcription factors to affect gene expression?
What has been found regarding functionally related genes in eukaryotes compared to prokaryotes?
What has been found regarding functionally related genes in eukaryotes compared to prokaryotes?
What is a plausible mechanism for the coordination of gene expression in eukaryotes?
What is a plausible mechanism for the coordination of gene expression in eukaryotes?
How can alternative RNA splicing result in different proteins from the same initial RNA transcript?
How can alternative RNA splicing result in different proteins from the same initial RNA transcript?
Explain posttranscriptional control in regulating mRNA degradation.
Explain posttranscriptional control in regulating mRNA degradation.
Compare mRNA degradation in eukaryotes and prokaryotes.
Compare mRNA degradation in eukaryotes and prokaryotes.
Summarize the steps of mRNA degradation.
Summarize the steps of mRNA degradation.
How are proteins targeted for degradation?
How are proteins targeted for degradation?
What is the role of noncoding RNAs?
What is the role of noncoding RNAs?
What is a microRNA (miRNA) and its two modes of action?
What is a microRNA (miRNA) and its two modes of action?
What is siRNA, and how is it similar and different from microRNA?
What is siRNA, and how is it similar and different from microRNA?
What three processes lead to the transformation of a zygote into an organism?
What three processes lead to the transformation of a zygote into an organism?
What occurs in cell differentiation and morphogenesis?
What occurs in cell differentiation and morphogenesis?
What are cytoplasmic determinants?
What are cytoplasmic determinants?
What are inductive signals?
What are inductive signals?
What is meant by determination in embryonic cells?
What is meant by determination in embryonic cells?
What process ensures that all tissues and organs of an organism are in their characteristic places?
What process ensures that all tissues and organs of an organism are in their characteristic places?
What is controlled by homeotic genes?
What is controlled by homeotic genes?
What mechanism is involved in the beginning of tumor growth?
What mechanism is involved in the beginning of tumor growth?
What are three mechanisms for converting a proto-oncogene to an oncogene?
What are three mechanisms for converting a proto-oncogene to an oncogene?
What are the functions of tumor-suppressor genes?
What are the functions of tumor-suppressor genes?
Describe the double whammy that results from mutation of p53.
Describe the double whammy that results from mutation of p53.
What is a polyp?
What is a polyp?
What is an adenoma?
What is an adenoma?
What is carcinoma?
What is carcinoma?
Study Notes
Regulation of Gene Expression in Prokaryotes and Eukaryotes
- Genes are not continuously active; E. coli activates genes for tryptophan production only when needed to conserve energy.
- Bacterial metabolism is controlled primarily through gene regulation and enzyme regulation.
Feedback Inhibition
- E. coli employs negative feedback inhibition for tryptophan synthesis, reducing production when in excess.
Operon Structure and Function
- Promoter: Binding site for RNA polymerase to initiate transcription.
- Operator: DNA segment that acts as a switch, located between the promoter and enzyme-coding genes.
- Operon: Combination of promoter, operator, and genes, regulated by repressor proteins which prevent transcription.
Repressor Proteins and Gene Regulation
- Repressor proteins bind to operators, blocking RNA polymerase and preventing transcription.
- Regulatory genes exist separately from operons and have their own promoters; an example includes the TATA box.
- Inducible operons are typically off but can be activated by small molecules, while repressible operons are usually on and can be repressed by specific molecules.
cAMP and CAP in Gene Expression
- CAP (Catabolite Activator Protein) enhances RNA polymerase binding to the promoter when activated by cAMP.
- Low glucose levels increase cAMP, promoting lac mRNA synthesis; high glucose reduces cAMP, decreasing lac mRNA production.
Gene Expression and Chromatin Modification
- Gene expression is primarily controlled at the transcription level, and chromatin structure influences this regulation.
- Heterochromatin is tightly packed and less active in gene expression, whereas euchromatin is loosely packed and more active.
- Histone acetylation increases gene expression likelihood by loosening DNA structure.
- DNA methylation typically suppresses gene expression by condensing chromatin.
Epigenetics and Gene Regulation
- Epigenetic inheritance refers to traits passed on without changes to the DNA sequence, illustrated by differences in identical twins.
- Enhancers and activators interact to stimulate transcription factors and promote RNA polymerase binding.
mRNA Regulation
- Prokaryotes degrade mRNA quickly (minutes), while eukaryotes take longer (hours to weeks).
- Degradation steps include shortening the poly-A tail, removing the 5' cap, and action by nucleases.
- Noncoding RNAs and microRNAs regulate gene expression during translation.
Cell Differentiation and Development
- Cell differentiation leads to specialized functions, while morphogenesis gives cells their shape.
- Cytoplasmic determinants are unevenly distributed maternal substances influencing early development.
- Inductive signals from embryonic cells direct changes via signal transduction pathways.
Homeotic Genes and Tumor Suppression
- Homeotic genes guide pattern formation in embryos.
- Oncogenes are mutated proto-oncogenes leading to cancer; mechanisms for conversion include DNA movement, gene amplification, and mutations.
- Tumor-suppressor genes, like P53, repair DNA and control cell adhesion and signaling; P53 mutations lead to loss of cell cycle regulation and repair mechanisms.
Cancer Types
- Polyp: Small benign growth.
- Adenoma: Larger benign growth.
- Carcinoma: Malignant tumor.
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Description
Explore the intricate mechanisms of gene expression regulation in E. coli through this flashcard quiz. Understand how metabolic needs dictate when genes are activated or turned off, thus conserving energy and resources. This quiz covers key concepts from Chapter 18 of your biology curriculum.
