Download Quiz 1 MCB141 103/104 * Quiz graded out of 6 points, but score will

Quiz 1
MCB141 103/104
* Quiz graded out of 6 points, but score will be multiplied by two for final grade (12pts)
1. Briefly describe one example (that has been covered in lecture) of synergistic gene control in
development (1-2 sentences). 1pt
Accepted several answers, including*:
- Specification of B7.5 blastomeres in sea squirt. Tbx6 and Lhx3 synergistically
activate Mesp only in B7.5 blastomeres.
- Induction of iPS cells requires the synergistic activity of several TFs, including Sox2,
Oct4, and Nanog. Together, these TFs activate genes required for pluripotency.
*If you were marked off and do not know why, come see me.
2. Name the three main pathways by which promoter-enhancer interactions activate
transcription. 1pt
-
Mediator complex
Swi/Snf
Histone modifying enzymes (HMEs)
3. Why did Yamanaka employ a selection procedure to identify induced pluripotent cells (1-2
sentences)? 1pt
The induction of cells to a pluripotent state was an incredibly rare event. A selection
procedure (i.e. antibiotic selection or lacZ) was used to easily identify cells in which
pluripotency had been induced.
Without a selection procedure, it would have been impossible to pick out the cells that had
been successfully induced.
I gave a lot of partial credit for this answer. If you have questions about your partial credit,
come see me.
4. Briefly describe how nurse cells contribute to the polarity of the Drosophila oocyte (1-2
sentences). ½ pt
Nurse cells synthesize and donate nutrients, proteins, and mRNAs to the developing oocyte
via ring canals. These mRNAs include bicoid, nanos, and oskar, which are essential to
establishing the initial anterior-posterior axis of the oocyte.
5.
Regarding maternal effect gene RNA in the Drosophila oocyte (fill in the blank!) 1pt:
___Biocid________ is anteriorly localized, while ___Nanos______ and ___Oskar________ are
posteriorly localized
6. Name two mechanisms that allow for the tight regulation of gene expression throughout
development. 1pt
I accepted many answers, including:
- Synergistic gene control / Combinatorial regulation
- Insulator DNA
- Affinity threshold model (and related answers)
- Short range repression
- Enhancer sequence specificity
- …and more
7. Gap genes subdivide the Drosophila embryo along the _anterior-posterior___ axis. ½ pt
8. Was there a topic that you found particularly confusing during Tuesday’s lecture?
Thanks for answering this! It wasn’t worth any points, but I really appreciate the
feedback.