BIOL 1362

Imagine working with the scientists who did this research. One of them proposes testing the hypothesis that Kitl is important to coat coloration. To do this, she plans to observe what happens when an engineered double-stranded microRNA precursor is expressed in mouse embryos. One strand of the precursor would be complementary to Kitl mRNA. How could this approach work to test the hypothesis?
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Imagine working with the scientists who did this research. One of them proposes testing the hypothesis that Kitl is important to coat coloration. To do this, she plans to observe what happens when an engineered double-stranded microRNA precursor is expressed in mouse embryos. One strand of the precursor would be complementary to Kitl mRNA. How could this approach work to test the hypothesis?
Adding the microRNA precursor to mouse embryos should lead to its being processed into a mature, single-stranded microRNA. The microRNA/RISC complex would be capable of base pairing to the target Kitl mRNA, leading to its cleavage. This would reduce levels of functional Kitl mRNA in the embryo. Postnatal mice could be examined to see if their coat color were lighter than normal. If so, then Kitl is important for normal coat color development.
The figure shows the structure of a typical eukaryotic gene. How does it differ from the structure of a bacterial operon?
Operons lack enhancers and introns.
Scientists discovered that the difference between blond and dark hair comes down in part to a single nucleotide difference in the DNA sequence of an enhancer that lies more than 350,000 base pairs away from the gene it controls. On average, blonds transcribe this gene less efficiently than people with dark hair. How can a tiny difference in a distant enhancer make a blond?
DNA looping could bring the enhancer bound by an activator physically close to the promoter even if the enhancer is a huge distance away along the DNA molecule.
Imagine discovering a loss-of-function mutation in a eukaryotic gene. You determine the gene's nucleotide sequence from the start site for transcription to the termination point of transcription and find no differences from the wild-type sequence. Explain where you think the mutation might be and how the mutation might be acting.
The mutation is likely in any type of regulatory sequence.The mutation is probably acting to reduce or prevent transcription initiation.
How can gene expression change in an individual cell in a multicellular eukaryotic organism?
The expression of specific genes is turned on or off by signal pathways activated by molecules secreted by nearby or distant cells.
Scientists discovered that the difference between blond and dark hair comes down in part to a single nucleotide difference in the DNA sequence of an enhancer that lies more than 350,000 base pairs away from the gene it controls. On average, blonds transcribe this gene less efficiently than people with dark hair. How can a tiny difference in a distant enhancer make a blond?
The enhancer is associated with a protein when the gene is being transcribed.