Gene Expression Regulation in Prokaryotes and Eukaryotes

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Questions and Answers

What is the function of the lac operon repressor in gene expression regulation?

It activates transcription by binding to the operator.

It inhibits transcription by blocking RNA polymerase. (correct)

It enhances the binding of activators to the promoter.

It converts glucose into lactose.

Which statement accurately defines a constitutive mutant?

A mutant that is unable to express any genes under any conditions.

A mutant that demonstrates variable gene expression based on temperature.

A mutant that expresses genes only in the presence of certain nutrients.

A mutant that expresses genes continuously regardless of environmental conditions. (correct)

How do glucose levels influence the expression of the lac operon?

High glucose levels decrease cAMP, reducing lac operon expression. (correct)

Low glucose levels activate negative control of the operon.

High glucose levels directly enhance lac operon activity.

Glucose has no effect on lac operon expression.

What role does UTR regulation play in gene expression?

It affects stability, localization, and translation of the mRNA. Signup and view all the answers

Which of the following best explains the difference between non-homologous end joining (NHEJ) and homology directed repair (HDR)?

NHEJ is error-prone, whereas HDR is more precise and utilizes a template. Signup and view all the answers

What is genomic imprinting and how does it affect gene expression?

It causes genes to be expressed differently depending on which parent they are inherited from. Signup and view all the answers

What is the purpose of using microRNAs (miRNA) in gene regulation?

To silence mRNA expression of target genes. Signup and view all the answers

What distinguishes a partial diploid mutant in the context of the lac operon?

It contains an extra copy of the lac operon, affecting repression sensitivity. Signup and view all the answers

What is the primary function of CRISPR in bacterial cells?

To protect against viral infections Signup and view all the answers

How do enhancers differ from promoters in gene regulation?

Enhancers can be far from the gene they regulate, while promoters are located directly at the gene's start. Signup and view all the answers

What role does negative control play in the lac operon?

It prevents the binding of RNA polymerase to the promoter. Signup and view all the answers

What is the primary difference between homology directed repair (HDR) and non-homologous end joining (NHEJ)?

HDR uses an existing template for DNA repair, while NHEJ does not. Signup and view all the answers

What is the significance of RNA interference (RNAi) in gene regulation?

RNAi targets mRNA for degradation, effectively silencing specific genes. Signup and view all the answers

How does genomic imprinting affect gene expression?

It results in the expression of only the maternal allele of a gene. Signup and view all the answers

What defines a constitutive mutant in genetic terms?

A mutant that exhibits constant expression of a gene regardless of environmental conditions. Signup and view all the answers

What experimental approach provides insight into chromatin structure related to gene expression?

DNAase-susceptibility experiments Signup and view all the answers

Study Notes

Regulation of Gene Expression in Prokaryotes

Replica plating identifies lac operon mutants
Constitutive mutants are always "on"
Partial diploid mutants show negative control (repressor protein and operator DNA sequence)
Operon is a group of genes regulated together
Glucose levels affect lac operon expression
Positive vs. negative control, combined control is valuable
Lac and trp operons have similar and different features

Regulation of Gene Expression in Eukaryotes

Genomic imprinting affects gene expression
Epigenetic modification is a mechanism
DNAase-susceptibility experiments reveal chromatin structure and gene expression
Enhancers and promoter-proximal elements affect tissue-specific expression
Iron response element is a UTR gene expression example
MicroRNAs (miRNA) can silence gene expression
Gene expression regulation differs at early and late stages

CRISPR/Cas System

CRISPR and Cas9 have natural functions and locations
CRISPR/Cas9 is used to alter eukaryotic genes
Non-homologous end joining (NHEJ) and homology-directed repair (HDR) are gene editing methods
Cas9 gene editing has limitations in humans

Lab Connections

Bacterial transformation relates to DNA sequences
New alleles arise, demonstrated by TAS2R38
DNA sequence data (chromatograms) correlate to genotype

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Description

This quiz covers the regulation of gene expression in both prokaryotes and eukaryotes, including topics such as operons, genomic imprinting, and the CRISPR/Cas system. Understand the mechanisms like epigenetic modifications and how environmental factors like glucose influence gene expression. Test your knowledge of gene control mechanisms and systems that impact gene behavior.