Gene Expression Regulation Quiz

The control of gene expression is important in prokaryotes because it allows them to respond quickly to changes in their environment by producing only the proteins they need when they need them. This saves energy and resources.

False (B)

<p>Operon (A)</p> Signup and view all the answers

<p>The binding site for repressor proteins (C)</p> Signup and view all the answers

<p>To break down lactose (B)</p> Signup and view all the answers

<p>Both negative and positive regulation (B)</p> Signup and view all the answers

<p>The inducer binds to the repressor protein, causing a conformational change in the repressor that prevents it from binding to the operator. This allows transcription to occur.</p> Signup and view all the answers

<p>The co-repressor binds to the repressor protein, activating the repressor to bind to the operator and block transcription. This helps to prevent the overproduction of a specific product.</p> Signup and view all the answers

<p>CAP (B)</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Sigma factors are proteins that bind to RNA polymerase and guide it to specific promoter sequences on DNA. This ensures that RNA polymerase initiates transcription at the correct locations.</p> Signup and view all the answers

<p>TATA box (D)</p> Signup and view all the answers

<p>Transcription factors are proteins that bind to specific DNA sequences in the promoter region of a gene. They can either activate or repress transcription, controlling the rate at which a gene is expressed.</p> Signup and view all the answers

<p>LacI (B)</p> Signup and view all the answers

<p>To activate transcription (C)</p> Signup and view all the answers

<p>The mediator complex acts as a bridge between transcription factors bound to enhancers or silencers, which may be located far away from the promoter, and the basal transcription apparatus. It allows for communication and coordination of gene expression.</p> Signup and view all the answers

<p>All of the above (D)</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>To inhibit translation (B)</p> Signup and view all the answers

<p>To degrade mRNA (B)</p> Signup and view all the answers

<p>Proteins can be tagged with a chain of ubiquitin, a small protein, which marks them for degradation by a cellular structure called the proteasome. Ubiquitination helps to control the lifespan of proteins, ensuring that unnecessary or damaged proteins are removed.</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

<p>Two major epigenetic mechanisms are DNA methylation and histone modification. DNA methylation involves the addition of methyl groups to cytosines in DNA, often silencing gene expression. Histone modification, such as acetylation, can alter the accessibility of DNA to transcription factors, influencing gene activity.</p> Signup and view all the answers

<p>True (A)</p> Signup and view all the answers

<p>Histone acetylation typically leads to a more relaxed chromatin structure, making the DNA more accessible to transcription factors and thus activating gene expression. Conversely, histone deacetylation can result in a more compact chromatin structure, which can inhibit transcription.</p> Signup and view all the answers

<p>False (B)</p> Signup and view all the answers

The process of regulating gene expression in a cell by controlling the rate of transcription of DNA into RNA.

Clusters of genes in prokaryotes that share a single promoter and are transcribed together.

A protein that binds to the operator region of an operon and prevents transcription of the genes.

The process of activating gene expression by removing or inactivating a repressor protein.

A molecule that binds to a repressor protein, inactivating it and allowing transcription to occur.

A type of operon that is regulated by a repressor protein. Transcription is induced by the presence of an inducer.

An operon regulated by a repressor protein. Transcription is repressed in the presence of a co-repressor.

A molecule that binds to a repressor protein, activating it and preventing transcription.

The lac operon is an inducible operon. Transcription is induced by the presence of lactose, which acts as an inducer.

The trp operon is a repressible operon. Transcription is repressed by the presence of tryptophan, which acts as a co-repressor.

A protein that binds to a specific DNA sequence called a CAP site and increases transcription efficiency.

A protein that helps guide RNA polymerase to specific classes of promoters in prokaryotes.

A sequence in DNA that binds to specific transcription factors and can either activate or inhibit transcription.

A sequence in DNA that binds to specific transcription factors and represses transcription.

A protein complex that binds to specific transcription factors bound to enhancers or silencers, and connects them to the basal transcription apparatus.

A structural motif found in many transcription factors, consisting of a helix-turn-helix structure, that allows binding to DNA.

The process of controlling gene expression after transcription, including alternative splicing, mRNA degradation, and protein longevity.

The process of producing different mRNA molecules from a single gene by splicing out different exons.

Small, non-coding RNA molecules that regulate translation by inhibiting the translation of target mRNAs.

Small, non-coding RNA molecules that are expressed from viral RNA or transposons and mediate the degradation of the original sequence.

The process of regulating the lifespan of proteins in a cell, often by tagging them for degradation by the proteasome.

Changes in gene expression that are not due to changes in the underlying DNA sequence. These changes can be influenced by environmental factors.

The process of adding a methyl group to a cytosine base in DNA.

A region of DNA that is rich in CpG dinucleotides (cytosine followed by guanine) and is often found in promoters.

A protein that adds acetyl groups to the histone tails, leading to chromatin opening and increased transcription.

A protein that removes acetyl groups from the histone tails, leading to chromatin closing and decreased transcription.

The complex of DNA and histone proteins that make up chromosomes.

The process of altering chromatin structure by adding or removing acetyl groups from histone tails, leading to changes in gene expression.

Proteins that bind to DNA and influence transcription.

Proteins that bind to common regulatory sequences in the promoter and are required for basal transcription.

Proteins that bind to uncommon regulatory sequences found only in the promoters of a few genes. They are often cell-, tissue-, or stage-specific.

A sequence in DNA that is recognized by RNA polymerase and where transcription begins.

A common promoter sequence in eukaryotes that is recognized by the TATA-binding protein (TBP) of the transcription factor TFIID.