Prokaryotic and Eukaryotic Gene Regulation

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Questions and Answers

What is the primary mechanism by which gene expression is regulated in prokaryotes?

  • Translation
  • Post-transcriptional modifications
  • Protein folding
  • Transcription (correct)

The operator region in an operon is responsible for:

  • Encoding the structural genes of the operon
  • Binding to RNA polymerase and initiating transcription
  • Acting as a switch controlling RNA polymerase access to the genes (correct)
  • Regulating the rate of translation

Which type of operon is usually active but can be repressed by the presence of a specific molecule?

  • Regulatory operon
  • Inducible operon
  • Repressible operon (correct)
  • Constitutive operon

Which of the following is an example of a repressible operon?

<p>trp operon (D)</p> Signup and view all the answers

What is the role of lactose in the regulation of the lac operon?

<p>It acts as an inducer, activating transcription (D)</p> Signup and view all the answers

Which of the following is NOT a level of eukaryotic gene regulation?

<p>Translational level (D)</p> Signup and view all the answers

Which of the following modifications generally suppresses gene expression?

<p>DNA methylation (D)</p> Signup and view all the answers

Enhancers are DNA regions that, when bound by activators, enhance the rate of:

<p>Transcription (C)</p> Signup and view all the answers

What is the role of cytoplasmic determinants during early development?

<p>They regulate gene expression in the embryo. (B)</p> Signup and view all the answers

How do oncogenes contribute to cancer development?

<p>They promote excessive cell division. (C)</p> Signup and view all the answers

Which type of stem cells can differentiate into any cell type, including extraembryonic tissues?

<p>Totipotent stem cells (A)</p> Signup and view all the answers

What is the significance of homeotic genes in development?

<p>They dictate the placement of body parts. (A)</p> Signup and view all the answers

What is a key characteristic of pluripotent stem cells?

<p>They have the potential to form any cell except extraembryonic tissues. (C)</p> Signup and view all the answers

What effect do tumor suppressor genes have on cell division?

<p>They acknowledge checkpoints for cell cycle regulation. (B)</p> Signup and view all the answers

Which biotechnology tool allows precise modifications to DNA?

<p>CRISPR-Cas9 (D)</p> Signup and view all the answers

How do viruses influence host gene expression?

<p>They integrate their genetic material into the host genome. (B)</p> Signup and view all the answers

What is one potential application of gene therapy?

<p>Repairing genetic mutations within an individual’s cells. (D)</p> Signup and view all the answers

What is the purpose of inductive signaling in developmental biology?

<p>To guide cells to adopt specific fates during development. (D)</p> Signup and view all the answers

Flashcards

What is an operon?

A gene regulation system in prokaryotes where a group of genes involved in a specific function are regulated by a single regulatory element, the operator.

What is a promoter?

The DNA sequence where RNA polymerase binds to initiate transcription.

What is an operator?

A segment of DNA that acts as a switch, controlling the access of RNA polymerase to the genes.

What is a repressible operon?

Operons that are typically active but can be inhibited when a specific molecule (corepressor) is present. These regulate the synthesis of biosynthetic pathways.

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What is an inducible operon?

Operons that are usually inactive but can be activated in the presence of a specific inducer. These regulate the breakdown of specific metabolites.

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What is epigenetics?

Chemical modifications of DNA or histone proteins that affect gene expression without altering the DNA sequence.

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What is DNA methylation?

The addition of methyl groups to DNA, which usually suppresses gene expression.

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What is histone acetylation?

The addition of acetyl groups to histone proteins, often enhancing transcription by loosening DNA-histone interactions.

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Cytoplasmic Determinants

Maternal substances within the egg that influence the early development of the embryo by regulating gene expression.

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Induction

The process where signaling molecules from one group of cells influence the development of another group, guiding cells to adopt specific fates.

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Pattern Formation

The development of spatial organization in tissues and organs, governed by homeotic genes that define the placement of body parts.

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Homeotic Genes

Genes that control the development of specific body segments or structures, influencing where parts are located.

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Stem Cells

Undifferentiated cells with the potential to develop into various cell types. They are crucial for development and tissue repair.

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Totipotent Stem Cells

Stem cells that can develop into any cell type, including extraembryonic tissues (like the placenta).

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Pluripotent Stem Cells

Stem cells that can differentiate into almost any cell type, excluding extraembryonic tissues.

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Multipotent Stem Cells

Stem cells that can develop into a limited range of cell types, often related to a specific tissue or organ.

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Oncogenes

Mutated proto-oncogenes that promote excessive cell division, contributing to cancer development.

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Tumor Suppressor Genes

Genes that normally inhibit cell division or promote programmed cell death (apoptosis). Mutations inactivates them, leading to unchecked cell proliferation.

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Study Notes

Prokaryotic Gene Regulation (16.2)

  • Gene expression in prokaryotes occurs primarily at the transcriptional level, conserving energy.
  • The operon model regulates gene expression
    • Promoter: DNA sequence where RNA polymerase binds.
    • Operator: DNA segment controlling RNA polymerase access.
    • Structural genes: Genes coding for related proteins.
  • Repressible operons are typically active but can be deactivated (repressed) when a specific molecule (corepressor) is present.
    • The trp operon, involved in tryptophan synthesis, is an example. High tryptophan levels activate the repressor, inhibiting transcription.
  • Inducible operons are usually inactive but can be activated (induced) by an inducer molecule.
    • The lac operon, involved in lactose metabolism, is an example. Lactose acts as an inducer, inactivating the repressor and allowing transcription.

Eukaryotic Gene Regulation (16.3)

  • Eukaryotic gene expression is a complex, multi-level process.
  • Epigenetic level: Modifications affect gene expression without changing the DNA sequence.
    • DNA methylation typically suppresses, and histone acetylation enhances transcription.
  • Transcriptional level: Transcription factors bind to DNA, influencing RNA polymerase recruitment.
    • Enhancers are DNA regions that increase transcription when bound by activators.
  • Post-transcriptional level: After transcription, RNA splicing removes introns.
    • Alternative splicing produces different mRNA variants.
  • Translational level: Protein binding to mRNA regulates translation initiation and efficiency.
  • Post-translational level: Protein modifications (e.g., phosphorylation) affect protein activity and stability.

Regulation of Gene Expression in Development (16.4)

  • Precise gene regulation is essential for development.
  • Cytoplasmic determinants are maternal substances affecting embryo development.
  • Induction is when signaling molecules influence cell development.
  • Pattern formation establishes spatial organization in tissues and organs, guided by homeotic genes.

Stem Cells and Development (16.5)

  • Stem cells are undifferentiated cells crucial for development and repair.
  • Totipotent stem cells can differentiate into any cell type, including extraembryonic tissues.
  • Pluripotent stem cells can differentiate into almost any cell type.
  • Multipotent stem cells differentiate into a limited range of cell types within a tissue or organ.

Cancer and Gene Regulation (16.6)

  • Cancer results from uncontrolled cell division due to gene mutations.
  • Oncogenes promote excessive cell division when mutated from proto-oncogenes.
  • Tumor suppressor genes normally inhibit cell division or promote apoptosis.
    • Mutations inactivate tumor suppressor genes, leading to uncontrolled proliferation.

Viruses and Gene Regulation (16.7)

  • Viruses can affect host gene regulation through integration of their genetic material into the host DNA.
  • Viral interactions provide insights into gene regulation and disease.

Biotechnology and Gene Regulation (16.8)

  • Biotechnology manipulates gene expression for various applications.
  • Recombinant DNA technology combines DNA from different sources.
  • Gene therapy introduces or alters genes to treat diseases.
  • CRISPR-Cas9 is a precise genome-editing tool with therapeutic potential.

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