Gene expression

Under which condition will the lac operon be transcribed?

• High glucose and low lactose

• High lactose and low glucose

• Low cAMP

• All of the above

How does DNA methylation affect gene expression?

• By directly blocking RNA polymerase binding to the promoter

• By attracting proteins that prevent transcription initiation

• By altering chromatin structure, making DNA less accessible

• All of the above

How do enhancers work?

• By directly binding RNA polymerase

• By recruiting activator proteins that interact with RNA polymerase

• By producing small molecules that activate transcription factors

• By modifying the DNA sequence near the promoter

How does histone acetylation affect gene expression?

• Makes DNA more tightly condensed, repressing transcription

• Makes DNA less accessible to transcription machinery

• Loosens chromatin structure, promoting transcription initiation

• Directly modifies the DNA sequence for increased RNA polymerase binding

Mutations in genes encoding DNA methyltransferases can lead to various diseases. What is the likely consequence of such mutations?

• Increased DNA methylation, leading to widespread gene silencing

• Decreased DNA methylation, leading to uncontrolled gene expression

• Faster DNA replication due to methylation changes

• Changes in the genetic code due to altered methylation patterns

While studying gene expression in a newly discovered organism, you identify clusters of genes with similar functions. However, unlike bacteria, these genes lack a single shared promoter. What is the most likely mechanism for regulating these genes in this organism?

• Operon-based control with separate inducers for each gene

• Independent promoters for each gene with individual regulatory elements

• Epigenetic modifications controlling access to individual genes

• A combination of operons and epigenetic regulation

Operons are advantageous for bacteria because they allow for:

• Constitutive expression of all genes in the operon

• Independent regulation of each gene within the operon

• Coordinated expression of functionally related genes in response to environmental cues

• Increased mutation rates within the operon

Which of the following histone modifications is most likely associated with active gene expression?

• Histone H3 trimethylation at lysine 9 (H3K9me3)

• Histone H3 acetylation at lysine 27 (H3K27ac)

• Histone H4 methylation at arginine 3 (H4R3me2)

• Histone H2A ubiquitination

Which of the following mechanisms is LEAST likely to contribute to this spatial gene expression pattern?

• The presence of tissue-specific transcription factors

• DNA methylation patterns established during early development

• The spatial distribution of regulatory elements within the genome

• Direct modification of the DNA sequence by signaling molecules

How could synthetic biologists utilize knowledge of gene expression to achieve their goals?

• By randomly inserting genes into a host organism and screening for desired phenotypes.

• By designing promoters with specific responsiveness to external stimuli for controlled gene expression.

• By introducing mutations into genes to disrupt their function and create novel phenotypes.

• By overexpressing all genes within an organism to enhance its metabolic capabilities.