AP Biology - Unit 6 Review: Gene Regulation
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Questions and Answers

Operons are ONLY used by __________ for gene regulation.

prokaryotes

What is the site on the DNA strand where transcription begins?

promoter

What is the on and off switch on the DNA segment that controls whether or not the gene is turned on or off?

operator

What is a protein that can turn off a gene by binding to the operator segment on the DNA strand?

<p>repressor</p> Signup and view all the answers

What do you call the group of genes along with the sections of DNA that regulate them in a prokaryote?

<p>operon</p> Signup and view all the answers

What is an example of an inducible operon?

<p>lac operon</p> Signup and view all the answers

What is an example of a repressible operon?

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

What is a regulatory mechanism that involves a repressor protein that turns the operon 'off' called?

<p>negative control</p> Signup and view all the answers

What is the term for when an operon is said to have a protein or enzyme that can turn them 'on' or enhance their function?

<p>positive control</p> Signup and view all the answers

What type of operon is usually off but can be stimulated when a small molecule interacts with the repressor protein?

<p>inducible operon</p> Signup and view all the answers

What type of operon is usually on but can be inhibited by a small molecule that binds allosterically to a repressor protein?

<p>repressible operon</p> Signup and view all the answers

What do regulatory genes produce?

<p>repressor proteins</p> Signup and view all the answers

What accumulates and activates CAP when ATP is scarce?

<p>cAMP</p> Signup and view all the answers

What is activated by cAMP and binds to the promoter of a lac operon?

<p>CAP</p> Signup and view all the answers

What are the proteins that eukaryotic DNA strands are wound around called?

<p>histone</p> Signup and view all the answers

What groups bind to histone proteins, causing DNA to be loose and transcribable?

<p>acetyl</p> Signup and view all the answers

Without acetyl groups, the eukaryotic DNA would be wound ________ and would not be able to be transcribed.

<p>tightly</p> Signup and view all the answers

What describes eukaryotic DNA that is loosely wound and contains acetyl groups?

<p>euchromatin</p> Signup and view all the answers

What describes eukaryotic DNA that is tightly wound around histone proteins and does not have acetyl groups?

<p>heterochromatin</p> Signup and view all the answers

When genes are ________ in eukaryotic DNA, they are OFF!

<p>methylated</p> Signup and view all the answers

In eukaryotic gene regulation, what do transcription factors interact with to control gene expression?

<p>proximal and distal control elements</p> Signup and view all the answers

Together, transcription factors and proximal and distal control elements allow for ______ _______ to bind and transcribe the eukaryotic DNA efficiently and effectively.

<p>RNA polymerase</p> Signup and view all the answers

The ________ controls what kind of eukaryotic genes are expressed in different cells.

<p>environment</p> Signup and view all the answers

________ and the ________ control the amount of time that a particular eukaryotic gene is carried out.

<p>5' capping, 3' poly-A tail</p> Signup and view all the answers

What is it called when different genes come from the same strand because different exons or introns are expressed?

<p>alternative splicing</p> Signup and view all the answers

What are produced by dicer proteins and tag mRNA for degradation or translation blocking?

<p>miRNA</p> Signup and view all the answers

What protein chops up mRNA into miRNA?

<p>dicer protein</p> Signup and view all the answers

What molecule tags a protein that is unnecessary?

<p>ubiquitin</p> Signup and view all the answers

What finds proteins that have been tagged by ubiquitin and chops them up?

<p>proteasome</p> Signup and view all the answers

This statement is true.

<p>True</p> Signup and view all the answers

Study Notes

Gene Regulation in Prokaryotes

  • Prokaryotes utilize operons as a mechanism for gene regulation.
  • Operon consists of a group of genes and DNA segments that regulate them.

Key Components of Operons

  • Promoter: The starting point for transcription where RNA polymerase binds to DNA.
  • Operator: Functions as an on/off switch to control the gene's activity.
  • Repressor: A protein that inhibits gene expression by binding to the operator.

Types of Operons

  • Inducible Operon: Typically in an OFF state, it can be activated when a small molecule interacts with the repressor, allowing transcription (e.g., lac operon).
  • Repressible Operon: Generally in an ON state, it can be turned OFF when a small molecule binds to a repressor, preventing transcription (e.g., trp operon).

Regulatory Mechanisms

  • Negative Control: A repressor protein turns the operon OFF.
  • Positive Control: Enhancements allow transcription to occur more readily, via a protein that facilitates RNA polymerase's binding to the promoter.

Regulatory Genes

  • Produce repressor proteins continuously at a low rate, located away from the operon with its own promoter.

Eukaryotic Gene Regulation

  • Histones: Proteins around which eukaryotic DNA is wound; their modification influences transcription.
  • Acetyl Groups: Attach to histones, loosening DNA winding for transcription accessibility.
  • Euchromatin: Loosely wound DNA with acetylated histones, transcriptionally active.
  • Heterochromatin: Tightly wound DNA lacking acetyl groups, transcriptionally inactive.

DNA Methylation and Gene Expression

  • Methylated genes in eukaryotic DNA are typically OFF.

Interaction of Transcription Factors

  • Transcription factors engage with proximal and distal control elements to regulate gene expression, enabling efficient binding of RNA polymerase.

Environmental Influence

  • The environment impacts the expression of eukaryotic genes, facilitating cell differentiation.

Transcriptional Modifications

  • 5' Capping and 3' Poly-A Tail: Modification processes that affect the stability of eukaryotic mRNA.
  • Alternative Splicing: Mechanism that results in multiple proteins from a single gene by varying exon inclusion/exclusion.

RNA Interference

  • miRNA (micro RNA): Small RNA molecules that tag mRNA for degradation or inhibit translation.
  • Dicer Protein: Enzyme that processes precursor RNA into miRNA.

Protein Tagging and Degradation

  • Ubiquitin: Tags unnecessary proteins for degradation.
  • Proteasome: Cellular machinery that degrades tagged proteins.

Summary of Gene Regulation

  • Gene regulation is crucial for cellular function and differentiation, with various mechanisms operating at both prokaryotic and eukaryotic levels.

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Explore essential concepts in gene regulation with this quiz based on AP Biology Unit 6. Review important terms such as prokaryotes, promoters, operators, and repressors, which are fundamental for understanding how genes are controlled. Perfect for students preparing for exams or seeking to reinforce their knowledge.

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