Critical Thinking Questions
- Prokaryotes possess a nucleus whereas eukaryotes do not, but eukaryotes show greater compartmentalization that allows for greater regulation of gene expression.
- Eukaryotic cells contain a nucleus whereas prokaryotes do not, and eukaryotes show greater compartmentalization that allows for greater regulation of gene expression.
- Prokaryotic cells are less complex and perform highly-regulated gene expression whereas eukaryotes perform less-regulated gene expression.
- Eukaryotic cells are more complex and perform less-regulated gene expression whereas prokaryotic cells perform highly-regulated gene expression.
Some human neonates are born with malformations in their brain and spinal cord if the developing fetus is exposed to alcohol during prenatal development. These individuals have otherwise healthy genomes. What might cause these unusual development patterns?
Which statement is correct regarding the distinction between prokaryotic and eukaryotic gene expression?
- Prokaryotes regulate gene expression at the level of transcription whereas eukaryotes regulate at multiple levels including epigenetic, transcriptional, and translational.
- Prokaryotes regulate gene expression at the level of translation whereas eukaryotes regulate at the level of transcription to manipulate protein levels.
- Prokaryotes regulate gene expression with the help of repressors and activators whereas eukaryotes regulate expression by degrading mRNA transcripts, thereby controlling protein levels.
- Prokaryotes control protein levels using epigenetic modifications whereas eukaryotes control protein levels by regulating the rate of transcription and translation.
Which of the following statements describes prokaryotic transcription of the lac operon?
- When lactose and glucose are present in the medium, transcription of the lac operon is induced.
- When lactose is present but glucose is absent, the lac operon is repressed.
- Lactose acts as an inducer of the lac operon when glucose is absent.
- Lactose acts as an inducer of the lac operon when glucose is present.
The lac operon consists of regulatory regions such as the promoter as well as the structural genes lacZ, lacY, and lacA, which code for proteins involved in lactose metabolism. What would be the outcome of a mutation in one of the structural genes of the lac operon?
- Mutation in structural genes will stop transcription.
- Mutated lacY will produce an abnormal β galactosidase protein.
- Mutated lacA will produce a protein that will transfer an acetyl group to β galactosidase.
- Transcription will continue but lactose will not be metabolized properly.
In some diseases, alteration to epigenetic modifications turns off genes that are normally expressed. Hypothetically, how could you reverse this process to turn these genes back on?
- In new seedlings, histone acetylations are present; upon cold exposure, methylation occurs.
- In new seedlings, histone deacetylations are present; upon cold exposure, methylation occurs.
- In new seedlings, histone methylations are present; upon cold exposure, acetylation occurs.
- In new seedlings, histone methylations are present; upon cold exposure, deacetylation occurs.
- Mutated promoters decrease the rate of transcription by altering the binding site for the transcription factor.
- Mutated promoters increase the rate of transcription by altering the binding site for the transcription factor.
- Mutated promoters alter the binding site for transcription factors to increase or decrease the rate of transcription.
- Mutated promoters alter the binding site for transcription factors and thereby cease transcription of the adjacent gene.
The Wnt transcription pathway is responsible for key changes during animal development. The transcription pathway shown in the figure uses arrows to represent activation and perpendicular symbols to represent repression of Wnt gene products.
Based on the pathway, how would blocking Wnt gene expression affect the production of Bar-1?
- The transcription rate would increase, altering cell function.
- The transcription rate would decrease, inhibiting cell functions.
- The transcription rate decreases due to clogging of the transcription factors.
- The transcription rate increases due to clogging of the transcription factors.
- RBPs can bind first to the RNA, thus preventing the binding of miRNA, which degrades RNA.
- RBPs bind the miRNA, thereby protecting the mRNA from degradation.
- RBPs methylate miRNA to inhibit its function and thus stop mRNA degradation.
- RBPs direct miRNA degradation with the help of a DICER protein complex.
How can external stimuli alter post-transcriptional control of gene expression?
- UV rays can alter methylation and acetylation of proteins.
- RNA binding proteins are modified through phosphorylation.
- External stimuli can cause deacetylation and demethylation of the transcript.
- UV rays can cause dimerization of the RNA-binding proteins.
Protein modifications can alter gene expression in many ways. Describe how phosphorylation of proteins can alter gene expression.
- Phosphorylation of proteins can alter translation, RNA shuttling, RNA stability, or post transcriptional modification.
- Phosphorylation of proteins can alter DNA replication, cell division, pathogen recognition, and RNA stability.
- Phosphorylated proteins affect only translation and can cause cancer by altering the p53 function.
- Phosphorylated proteins affect only RNA shuttling, RNA stability, and post-translational modifications.
- UV rays could cause methylation and deacetylation of the genes that could alter the accessibility and transcription of DNA.
- The UV rays could cause phosphorylation and acetylation of the DNA and histones which could alter the transcriptional capabilities of the DNA.
- UV rays could cause methylation and phosphorylation of the DNA bases which could become dimerized rendering no accessibility of DNA.
- The UV rays can cause methylation and acetylation of histones making the DNA more tightly packed and leading to inaccessibility.
New drugs are being developed that decrease DNA methylation and prevent the removal of acetyl groups from histone proteins. Explain how these drugs could affect gene expression to help kill tumor cells.
- These drugs maintain the demethylated and the acetylated forms of the DNA to keep transcription of necessary genes on.
- The demethylated and the acetylated forms of the DNA are reversed when the silenced gene is expressed.
- The drug methylates and acetylates the silenced genes to turn them back on.
- Drugs maintain DNA methylation and acetylation to silence unimportant genes in cancer cells.
- Understanding gene expression patterns in cancer cells will identify the faulty genes, which is helpful in providing the relevant drug treatment.
- Understanding gene expression will help diagnose tumor cells for antigen therapy.
- Gene profiling would identify the target genes of the cancer-causing pathogens.
- Breast cancer patients who do not express EGFR can respond to anti-EGFR therapy.
- Personalized medicines would vary based on the type of mutations and the gene’s expression pattern.
- The medicines are given based on the type of tumor found in the body of an individual.
- The personalized medicines are provided based only on the symptoms of the patient.
- The medicines tend to vary depending on the severity and the stage of the cancer.