BIO2581 Section 31

Which of the following statements best distinguishes between trans-acting and cis-acting elements in gene regulation?

• Trans-acting elements are regulatory DNA sequences that influence gene expression only on the same DNA molecule, while cis-acting elements are diffusible proteins that can act on multiple DNA molecules.
• Cis-acting elements are regulatory DNA sequences that influence gene expression only on the same DNA molecule, while trans-acting elements are diffusible proteins that can regulate genes on different DNA molecules.
• Both cis-acting and trans-acting elements are diffusible proteins that can regulate genes located on different DNA molecules.
• Both cis-acting and trans-acting elements are regulatory DNA sequences that influence gene expression only on the same DNA molecule.
• None of the above

In the Drosophila embryo, nanos and pumilio work together to suppress the translation of the hunchback protein (HB protein) in mRNA in the posterior region. What would be the expected outcome if both nanos and pumilio became absent or underwent a loss of function?

• a) Hunchback protein would be expressed uniformly throughout the embryo, and abdominal segments would not form.
• b) Hunchback protein would only be expressed in the anterior region, and abdominal segments would form normally.
• c) Hunchback protein would not be expressed at all, and abdominal segments would not form.
• d) Hunchback protein would be expressed only in the posterior region, and abdominal segments would form normally.
• e) Hunchback protein would be expressed at low levels throughout the embryo, and abdominal segments would form but with defects.

You have discovered a new transposable element and want to figure out what type it is. Using yeast, you insert a fragment that contains an intron into your element, After transposition you notice that the entire fragment of dna is found at another location with the intron retained, and the original fragment is not there anymore. what type of transposon is it?

• Type 1 retrotransposon
• Type 2 replicative transposon
• Type 1 cut and paste transposon
• Type 2 cut and paste transposon
• N/A

Which of the following is not a possible consequence of transposons

• Decrease in gene expression
• Loss of gene function
• Increase in amount of coding DNA
• Increase in genome size
• None of the above

What Are the Mechanisms of Transposon Movement?

• Type 1 transposons copy themselves using an RNA step, so they make extra copies, while Type 2 transposons just move from one place to another without copying themselves.
• Type 1 transposons move by cutting themselves out and pasting elsewhere, while Type 2 transposons copy themselves using RNA.
• Both types move by cutting and pasting, but Type 1 always flips the order of the genes.
• Both types copy themselves with RNA, but Type 2 never makes extra copies.
• None of the above are correct.

Which of the following scenarios best describes a cis-acting mutation?

• A mutation in a transcription factor that prevents it from binding to the promoter of multiple target genes across the genome.
• A mutation in the operator of the lac operon that prevents the repressor from binding, leading to continuous expression of the operon.
• A mutation in an enhancer sequence that reduces the expression of multiple genes located on different chromosomes.
• A mutation in an RNA polymerase enzyme that decreases transcription efficiency for multiple genes in the cell.
• A mutation in a promoter region that decreases transcription of a single adjacent gene but does not affect other genes elsewhere in the genome.