BIO 529 F05
Exam II
Name______________________
ID #_______________________
1. Fill in the blanks with the best answer from the list provided. Answers may be used more
than once. (1 pt each)
archenteron
bottle cells
Hensen’s node
Noggin
node
gastrulation
morphogen
spina bifida
Hunchback
superficial
Cerberus
holoblastic
telolecithal
hyalin
delamination
involution
ingression
neural plate
GSK-3
ingression
karyokinesis
Gurken
notochord
holoblastic
Pair-rule
epithelial
archenteron
zona pellucida
primitive groove
neural tube
Nanos
regulative
BMP-4
spina bifida
isolecithal
gray crescent
Cerberus
Frz-b
isolecithal
notochord
Chordin
Disheveled
Goosecoid
-catenin
blastopore
centrolecithal
homeotic selector
Serine protease
Wnt
deuterostome
TGF-
Animal hemisphere
cytokinesis
neurulation
Vegetal hemisphere
nanos
epiboly
gap genes
FGF
cleavage
EGF receptor
GSK-3
Torso
Gurken
Bicoid
primitive groove
jelly layer
anencephaly
meroblastic
BMP4
karyokinesis
Hedgehog
Frz-b
neural groove
Spemann’s organizer
Nieuwkoop center
epithelial
zona pellucida
Marginal zone
regulative
neural tube
mosaic
mid-blastula transition
syncytial
segment polarity
mesenchyme
pair-rule
anterior visceral endoderm
gray crescent
Mitosis-promoting factor
invagination
primitive streak
Protein that negatively regulates Wnt signaling
Movement of cells by becoming mesenchymal and internalizing
Division of nucleus without cellular division
Ligand active in the developing Drosophila oocyte that specifies both
A/P and D/V axes
Structure that forms from the chordamesoderm
Cleavage in which entire embryo divides
Type of patterning gene that is expressed in alternate segments in
Drosophila embryo
Type of cell with tight associations with surrounding tissue
Primitive gut
Mammalian egg structure that must be removed before implantation
Name for the chick blastopore (not the DLB)
Structure induced to form by the notochord
Posteriorizing protein in Drosophila embryo
Type of development that Xenopus embryos undergo (with regard to
specification)
Molecule that specifies the ventral side of the amphibian embryo
Failure of the posterior region of the neural tube to close
Type of egg with very little yolk
Region of amphibian embryo opposite site of sperm entry
Two Wnt inhibitors that are secreted, extracellular proteins
1
BIO 529 F05
Exam II
Name______________________
ID #_______________________
For all remaining questions, you must show your work or explain your reasoning to receive
any partial credit.
2. List five differences between early development in mammals as compared with other
vertebrates. Be specific. (10 pts)
Compaction of the embryo
Very slow cell divisions (12-24 hrs)
Early MBT
Two organizing centers (node and AVE)
Rotational cleavage
Very small size
Two distinct early tissue types (trophoblast and ICM)
Internal development
3a. Describe the process of secondary neurulation, at the cellular/tissue level. (5 pts)
-See text p.398 and lecture notes (11/1)
b. Where does secondary neurulation occur? (2 pts)
At the posterior of the embryo
c. What tissue is most directly required to induce secondary neurulation? (2 pts)
notochord
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BIO 529 F05
Exam II
Name______________________
ID #_______________________
4. In C. elegans, the identity of the cell that is the precursor of the germline is determined by the
presence of P granules. The P granules are actively transported into only one cell during
each cleavage division.
a. What are the two general mechanisms that can be used to divide components of the cell
during? (4 pts)
actin-based microfilaments and tubulin-based microtubules move components
around the cell
b. How would one test which of these two mechanisms is used for segregation of specific
components? Be specific and be sure to describe the possible results and their
interpretations. (6 pts)
One can add a specific inhibitor to the developing embryo (colchicine or
nocodazole to inhibit tubulin polymerization, or cytochalasin B to inhibit actin
polymerization) and ask whether the P granules move to the posterior cell or not.
If colchicine inhibits the movement, but cytochalasin B does not, then tubulinbased microtubules must be responsible for P granule movement. If the reverse
occurs, then actin-based microfilaments are responsible.
c. Which mechanism is used for transport of the P granules? (2 pts)
actin-based microfilaments
d. In development of an embryonic axis of Drosophila, segregation of cytoplasmic
components is also important. Which axis is determined in this way, what are the
cytoplasmic components that are segregated, and where do they go? (6 pts)
During A/P axis formation, Drosophila bicoid mRNA is transported to the anterior
pole while nanos mRNA is transported to the posterior.
e. Which mechanism is used for transport of the cytoplasmic determinants in the Drosophila
egg? (2 pts)
tubulin-based microtubules
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BIO 529 F05
Exam II
Name______________________
ID #_______________________
5a. What are the names of the classes of genes used to specify regional (segmental) identity in
mouse and flies? (Give one name used to describe the fly genes and for mouse) (2 pts)
Homeotic selector genes in flies, Hox genes in mouse
b. Describe three ways in which the genes that specify regional identity in these organisms
are similar. (9 pts)



Similar in protein structure (all are homeobox transcription factors)
Similar in distribution in the genome (found in clusters)
Similar in distribution of expression within the organism (Most 3’
expressed most anteriorly to most 5’ expressed most posteriorly)
6. Classify the following organisms with respect to the following features. (6 pts)
Organism
Cleavage Type
Egg Type
sea urchin
holoblastic
isolecithal
tunicate
holoblastic
isolecithal
frog
holoblastic
mesolecithal
Cleavage Type is holoblastic or meroblastic
Egg Type is centrolecithal, isolecithal, mesolecithal, or telolecithal
7. Name the four classes of genes that produce the segmentally reiterated pattern in the
Drosophila embryo and indicate the order in which they are active. (8 pts)
1.
2.
3.
4.
Maternal genes
Gap genes
Pair-rule genes
Segment polarity genes
Note that the homeotic selector genes are not involved in producing the
segmentally reiterated pattern, they are involved in distinguishing segments.
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BIO 529 F05
Exam II
Name______________________
ID #_______________________
8. The early development of C. elegans includes both autonomous and conditional specification.
As described above, the presumptive germline cells (P lineage) is determined autonomously
by the presence of P granules. However, at the 4 cell stage (which includes ABa, ABp, EMS,
and P2 cells), specification of the ABp and EMS cells is conditional. Describe the cell
interactions necessary for specification of each of these cells, including the molecular signal
and the source of the signal for each. (8 pts)
Both cell types require interaction with the P2 cell for proper specification. The
P2 cell makes MOM-2, a Wnt ligand, that activates the MOM-5 Frizzled receptor on
the EMS cell. This is essential to specify endoderm formation from EMS cells.
The P2 cell also makes APX-1, a Delta ligand, that activates GLP-1, Notch, on the
ABp cell. Both the ABa and ABp cells make GLP-1, but only ABp is in contact
with P2, therefore receives the signal. This is essential to specify the ABp cell
distinctly from the ABa.
9. In the tunicate Styela partita, we know from Conklin’s early work that the pigmented yellow
cytoplasm of the embryo segregates into the cells that ultimately form the muscle of the
embryonic tail.
a. What molecule in the yellow cytoplasm has been identified as important for muscle
development? (2 pts)
macho-1 mRNA
b. How would one experimentally show that this molecule is necessary for muscle
development? Include expected results. (3 pts)
Knock down macho-1 RNA in the developing embryo with morpholinos or dsRNA.
If the muscle fails to develop, then macho-1 is necessary for muscle
development. This is what happens.
c. How would one experimentally show that this molecule is sufficient for muscle
development? Include expected results. (3 pts)
Inject macho-1 mRNA into a region of the developing embryo that does not
normally produce muscle. If the cells into which the mRNA is injected give rise to
muscle, then macho-1 is sufficient for muscle development. This is what
happens.
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