Title: Gene Expressions
Course: Question Banks

Q: Gene expression is ________.
- simply transcription (Incorrect. Gene expression is not only transcription.)
- only translation (Incorrect. Gene expression is not only translation)
- both transcription and translation (Correct. Expression of a gene involves transcription of DNA into RNA followed by translation to a functional protein.)
A: both transcription and translation

Q: ________ is required to give cells unique specializations.
- Protein synthesis (Incorrect. Protein synthesis alone would be make cells unique.)
- DNA replication (Incorrect. DNA replication should be the same in all cells of a multicellular organism.)
- Gene expression (Correct. Without difference in gene expression, cells could have not unique functions in an organism.)
A: Gene expression

Q: Cells express different genes in response to ________.
- internal triggers (Incorrect. Cells do not express different genes only in response to internal triggers.)
- external signals (Incorrect. Cells do not express different genes only in response to external triggers.)
- internal triggers and external signals (Correct. Internal and external signals can both result in different gene expression patterns in cells.)
A: internal triggers and external signals

Q: In ________, transcription and translation occur simultaneously.
- eukaryotes (Incorrect. In eukaryotes transcription and translation occur in two very different cellular locations.)
- both prokaryotes and eukaryotes (Incorrect. In eukaryotes transcription and translation occur in two very different cellular locations.)
- prokaryotes (Correct. Because DNA is not sequestered in a nucleus away from translation machinery like ribosomes, transcription and translation occur almost simultaneously in prokaryotes.)
A: prokaryotes

Q: Prokaryotic gene regulation occurs at the level of ________.
- translation (Incorrect. Gene regulation is not at the level of translation in prokaryotes.)
- both transcription and translation (Incorrect. Gene regulation is not at the level of translation in prokaryotes.)
- transcription (Correct. Gene regulation in prokaryotes occurs by regulating which DNA is transcribed.)
A: transcription

Q: ________ gene regulation occurs from transcription beyond translation.
- Prokaryotic (Incorrect. Gene regulation in prokaryotes occurs by regulating which DNA is transcribed.)
- Both eukaryotic and prokaryotic (Incorrect. Gene regulation in prokaryotes occurs by regulating which DNA is transcribed.)
- Eukaryotic (Correct. Gene regulation in eukaryotes occurs from DNA transcription through post-translational modification of proteins.)
A: Eukaryotic

Q: In prokaryotes, structural proteins in a single biochemical pathway are usually found as a(n) ________ within the genome.
- cluster (Incorrect. The proteins are often encoded together within the genome but we don’t call them a cluster.)
- polycistronic transcript (Incorrect. This is the term for the mass transcription of proteins with related functions.)
- operon (Correct. Proteins with related functions are usually encoded together in a block called an operon.)
A: operon

Q: Gene products that are needed consistently are ________ in prokaryotes.
- always on (Incorrect. While arguably true, this isn’t the terminology we use.)
- activated (Incorrect. Activation refers to the increased transcription of a gene in response to a specific external stimulus.)
- constitutively expressed (Correct. These genes are transcribed and translated continuously to provide the cell with constant levels of the protein products.)
A: constitutively expressed

Q: In prokaryotes the ________ is located between the RNA polymerase binding site and the transcriptional start of the first gene in an operon.
- repressor (Incorrect. A repressor is a transcription factor that suppresses transcription in response to an external stimulus.)
- inducer (Incorrect. An inducer is a regulatory molecule that may activate or repress transcription.)
- operator (Correct. The operator is a regulatory region between the RNA polymerase binding site and the start of transcription that a repressor or inducer may bind.)
A: operator

Q: ________ operons typically contain genes encoding components in biosynthetic pathways.
- Activator (Incorrect. There are no activator operons.)
- Inducible (Incorrect. Inducible operons are usually associated with metabolism of specific substrates.)
- Repressible (Correct. Biosynthetic pathways are usually associated with repressible operons that are constitutively expressed until the biosynthesis product is no longer needed.)
A: Repressible

Q: The ________ operon contains five genes that are switched off when tryptophan is present in the environment.
- amino acid (Incorrect. While tryptophan is an amino acid, this is not the name of the operon.)
- repressed (Incorrect. This operon is a repressible operon but that is not its name.)
- trp (Correct. The trp operon is repressed when tryptophan is present in the environment.)
A: trp

Q: In prokaryotes, the trp operon is under ________ that ________ prevents RNA polymerase from binding.
- positive regulation; biochemically (Incorrect. This is not how the trp operon is regulated.)
- negative regulation; biochemically (Incorrect. RNA polymerase is not biochemically prevented from binding the mRNA template.)
- negative regulation; physically (Correct. Negative regulators bind the operator and physically prevent RNA polymerase from transcribing the genes contained in the trp operon. This is considered negative regulation because the genes are kept turned off by these factors.)
A: negative regulation; physically

Q: In order for the lac operon to be triggered, lactose must be present and ________.
- glucose levels high (Incorrect. High levels of glucose will prevent binding of an activating protein.)
- cAMP levels low (Incorrect. If cAMP levels are low, the catabolite activator protein will not form the CAP-cAMP complex required to actually activate the operon.)
- glucose stores depleted (Correct. Lactose removes the lac repressor protein while low glucose levels allow an activating protein to bind to the operon.)
A: glucose stores depleted

Q: Genes associated with metabolism of a specific substance, such as lactose, are typically contained on ________ operons.
- activator (Incorrect. There are no activator operons.)
- repressible (Incorrect. Biosynthetic pathways are usually associated with repressible operons.)
- inducible (Correct. Inducible operons are usually associated with metabolism of specific substrates, so their expression is induced (triggered) by the presence of the substance.)
A: inducible

Q: The main role of the catabolite activator protein is to ________.
- remove a repressor from the lac operon (Incorrect. This is not the role of CAP.)
- trigger transcription of the lac operon (Incorrect. This is not the role of CAP.)
- increase the binding ability of RNA polymerase to the lac operon promoter region (Correct. This is the main role of CAP in positive regulation of the lac operon.)
A: increase the binding ability of RNA polymerase to the lac operon promoter region

Q: Changes in gene regulation that are caused by modifications to histones and the DNA, but not the nucleotide sequence itself, are known as ________.
- hypermethylation (Incorrect. Hypermethylation is an example of this type of regulation.)
- CpG islands (Incorrect. CpG islands often experience this type of gene regulation.)
- epigenetic (Correct. These regulations “around genetic” sequences are temporary and do not directly alter the nucleotide sequence.)
A: epigenetic

Q: The key to epigenetic regulation is ________.
- physical modification of the DNA (Incorrect. There is no physical modification of the actual DNA strand.)
- biochemical modification of binding factors (Incorrect. Binding factors are not modified in any way by epigenetic modifications.)
- controlling accessibility to transcription factors and RNA polymerase binding (Correct. Epigenetic changes influence whether the DNA strand is open to expose the template.)
A: controlling accessibility to transcription factors and RNA polymerase binding

Q: Tightly coiled DNA is ________.
- known as hypermethylated (Incorrect. Hypermethylation is one factor that influences how tightly DNA is coiled.)
- translationally regulated (Incorrect. Tight coiling of DNA does not regulate translation.)
- transcriptionally inactive (Correct. Tightly coiled DNA cannot be accessed by transcription machinery.)
A: transcriptionally inactive

Q: For transcription to begin in eukaryotes, ________ must bind the DNA first.
- RNA polymerase (Incorrect. In eukaryotes, RNA polymerase is not the first thing that binds to the DNA molecule.)
- enhancers (Incorrect. Enhancers are regions of DNA that help increase transcription.)
- transcription factors (Correct. Transcription factors must bind to the promoter region first and then recruit RNA polymerase to begin transcription.)
A: transcription factors

Q: ________ brings an enhancer into contact with transcription factors and other proteins to increase transcription.
- Mediator protein (Incorrect. Mediator proteins are one of the other proteins that enhancers interact with to increase transcription.)
- RNA polymerase plus (Incorrect. There is no RNA polymerase plus.)
- DNA-bending protein (Correct. This protein brings the enhancer into physical proximity with transcription factors and mediator proteins.)
A: DNA-bending protein

Q: A(n) ________ element is next to the gene being transcribed on the same chromosome.
- trans-functional (Incorrect. There is no such thing as a trans-functional element in gene regulation.)
- enhancer (Incorrect. Enhancers are not necessarily on the same chromosome next to the gene they influence.)
- cis-acting (Correct. A cis-acting element is ‘in line’ with the gene it is influencing.)
A: cis-acting

Q: RNA splicing occurs in the ________.
- nuclear membrane (Incorrect. No RNA modifications occur in the nuclear membrane.)
- cytoplasm (Incorrect. Only mature mRNA is found in the cytoplasm.)
- nucleus (Correct. Pre-mRNA is spliced into mRNA before the transcript leaves the nucleus.)
A: nucleus

Q: RNA splicing removes ________ from the RNA transcript.
- axons (Incorrect. Axons are parts of neurons.)
- exons (Incorrect. Exons are the regions of RNA that code for proteins.)
- introns (Correct. Introns must be removed from the transcript before mature mRNA can be translated.)
A: introns

Q: Alternative splicing allows ________.
- the same mRNA sequence to be created from different DNA templates (Incorrect. Different DNA templates cannot be used to generate the same mRNA.)
- some introns to be left in coding regions to protect the mRNA (Incorrect. Introns do not protect the mRNA.)
- different protein products to be produced from one gene (Correct. Alternative splicing stitches together different combinations of exons from the same pre-mRNA. This allows for a single gene to encode for multiple protein products.)
A: different protein products to be produced from one gene

Q: The rate at which RNA decays is known as ________.
- half-life (Incorrect. Half-life indicates the rate at which radioactive isotopes decay.)
- RNA longevity (Incorrect. This is not the correct term.)
- RNA stability (Correct. RNA stability is the rate at which an RNA molecule decays once in the cytoplasm.)
A: RNA stability

Q: The ________ of mRNA regulate localization, stability, and translation.
- RNA-binding proteins (Incorrect. RBPs bind to these regions of mRNA.)
- introns (Incorrect. mRNA (meaning mature in this case) does not contain any introns.)
- untranslated regions (Correct. UTRs are just upstream or downstream of protein-coding regions and play a role in regulating mRNA localization, stability, and protein translation.)
A: untranslated regions

Q: ________ play a role in destroying mRNA targets.
- siRNAs (Incorrect. Short-interfering RNAs can trigger mRNA degradation but this is not a normal regulatory process.)
- RBPs (Incorrect. Some RNA-binding proteins play a role in stabilizing mRNA targets; they do not all play a role in degradation.)
- miRNAs (Correct. microRNAs bind to an mRNA target along with RISC to degrade that molecule.)
A: miRNAs