Final exam Review Sheet - MCD Biology

MCDB 4650 DEVELOPMENTAL BIOLOGY Fall 2011
Review topics for the Cumulative Exam
As you prepare for the final exam, I hope you will consider some of the elements I have stressed throughout the
semester: thinking critically, analyzing the results of experiments, designing experiments to test hypotheses, and
integrating the many things you know into a bigger picture. The statements below may help you to organize
your thinking, but you may also wish to review the learning goals for each class period. The exact functions of
only a few molecules are required, as listed below. The final exam is worth 90 points. Good luck!
1. Transcriptional and translational control of gene regulation during development: how common mechanisms
(alternative splicing, methylation, enhancers and silencers) determine the output of a gene. Combinatorial
control.
2. Specification of cell fate:
a. The concept of morphogens: what they do, how they work, and some specific examples of morphogens.
b. Signaling vs. cytoplasmic determinants: how both systems can work to specify cell fate, and how one can
experimentally differentiate which mechanism is being used. Remember the difference between cell
fate, commitment and differentiation.
c. Examples and mechanisms of lateral inhibition for specifying cell fates among cells of an equivalence
group.
3. Cleavage: its importance and what it accomplishes for the different embryos studied; how different patterns
of cleavage impact development, the importance of the mid-blastula transition
4. Inductive events: the initial establishment of three germ layers and body axes in Xenopus
a. The roles of initial axis determination by maternal components, cortical rotation, the initiation of the
Nieuwkoop center, and the Spemann organizer in the eventual organization of the embryo.
b. How mesoderm induction (and neural induction) were studied (experimentally) and the signaling
molecules involved (remember roles of Dsh, Xnrs, BMPs, BMP blockers (Noggin, etc)
5. Morphogenesis: gastrulation and neurulation. What kinds of movements take place that allow the embryo to
reorganize? How and why do cells change shape and move, and why is this important to the embryo?
6. Neural fate determination, neuronal differentiation and synapse formation
a. Neural fate using cerebral cortex and retina as models: the general principles of how a neuron’s fate can
be established.
b. Overall principles involved in axonal pathfinding-- guiding both cells and axons to their final destinations
within the embryo (spinal cord, retino-tectal projections)
c. Plasticity, and the general principles of how axons maintain connections
d. Molecules (general roles for): Shh, BMPs, Eph receptors and ligands, Notch/Delta, NGF, neurotrophins
7. The genetic approach to analyzing developmental processes
a. Exploratory and manipulative genetics techniques and rationale for use
b. The distinction between maternally and embryonically contributed gene products, and how genetics can
uncover when such products are required in the embryo.
c. Interpreting the results of genetic crosses or other genetics experiments in terms of function of genes and
interactions of gene products (epistasis).
d. Transgenic animals and their uses in worms, flies, and mice, and how they are made (including HR and
Cre-lox).
e. the processes underlying segmentation in Drosophila: general functions of egg polarity, gap genes, pair
rule genes and how expression of each of these classes of transcripts is controlled (transcriptional

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activators and repressors; combinatorial control!), and how the genetic approach was important for
discovering all of this!
8. Roles of Hox genes in Drosophila, amphibians, and mammals. Be familiar with the general phenotypes of
LOF or GOF mutations in Hox genes, and the importance of their conservation across all animals.
9. The principles that underlie limb patterning: models for explaining the patterning, and the involvement of
different molecules and their interactions in establishing the different axes, and the conservation of limb
development across animals.
10. Sex determination, Dosage Compensation and Imprinting
a. Primary and secondary sex determination in mammals (molecules: SRY, AMH, testosterone), compared
to sex determination in C. elegans and Drosophila (X:A ratio)
b. General mechanisms of dosage compensation (differences, similarities between C. elegans, Drosophila
and mammals) and X chromosome inactivation in mammals (Xist).
c. Imprinting: possible evolutionary reasons, general mechanism, and how to determine which copy
(maternal or paternal) is imprinted (be able to interpret experiments or crosses to figure out which copy is
imprinted)
11. Stem cells and their uses, medical implications
a. general properties of stem cells (progressive restriction; committed stem cells vs. multipotent stem cells)
b. embryonic stem cells: developmental potential, ways to control differentiation, difference between
reproductive and therapeutic cloning
c. clinical potential of therapeutic cloning and iPS cells.