NAME____________________________________
BIOLOGY 52 - - CELL AND DEVELOPMENTAL BIOLOGY - - FALL 1999
Fourth Examination - - December 1999
Answer each question, noting carefully the instructions for each.
Repeat- Please read the instructions for each question before answering!!!
Be specific in each answer, and print name on top of each page! (I mean it!)
--------------------------------------------------------------------------------------------------------------------1. The following 6 true-or-false questions are worth 10 points in total. Mark each as T or F and for
any that is/are false, indicate briefly why in the space below.
a.
T F
Isolated animal pole cells make endoderm.
b.
T F When animal pole cells are cultured with vegetal pole cells, the animal pole cells make
c.
T F
Isolated vegetal pole cells make ectoderm.
b.
T F
When vegetal pole cells are cultured with animal pole cells, the vegetal pole cells make
e.
T F
Blood borne hormones regulate insect metamorphosis.
f.
T F
The receptors for steroid hormones are transmembrane receptor tyrosine kinases.
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2. (circle all correct answers- 2 pts) Which genes contain binding sites for myoD in their promotor?
A. Skin keratin.
D. A bone specific-ECM component.
B. A brain-specific tubulin.
E. Fruit fly Engrailed.
C. A skin-specific hemidesmosome protein.
F. Muscle-specific actin.
(2 points) Which of the three germ layers should express myoD? ________________________
3. (4 points) We discussed several mechanisms by which cells remember the decisions they make.
What mechanism is affected by treating cells with azacytidine? _________________________
When cultured fibroblasts were grown for several cell generations in azacytidine, they did something
remarkable. What? _____________________________________________________________
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4. The following four true-or-false questions are worth 5 points in total. Mark each as T or F and for
any that is/are false, indicate briefly why in the space below.
a. T F Ecdysone is a steroid hormone.
b. T F Fruit fly development begins with many nuclei in one cell.
c. T F In embryos mutant for Notch, all ventral ectodermal cells become neural cells.
d. T F Engrailed encodes a receptor tyrosine kinase that is the receptor for wingless.
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5. (2 points- Put letter corresponding to all correct answers in the blanks)
A particular equatorial cell in a frog embryo undergoes the following steps in its development.
A
B
C
Animal pole ---> Ventral/intermediate mesoderm -----> ventral mesoderm ---> muscle cell
At which step(s) is the cell making determination decisions ____________________
At which step(s) is the cell differentiating ____________________
6. (8 points) Use the choices below to fill in each blank:
a.
b.
c.
d.
Secreted or membrane-bound cell-cell signal.
Transmembrane receptor.
G protein.
Transcription factor.
Hunchback protein acts as a _____________
Lin-12 protein acts as a ___________________
Engrailed protein acts as a _____________
Notch protein acts as a __________________
Wingless protein acts as a _____________
Steel protein acts as a _________________
ras protein acts as a __________________
MyoD protein acts as a ___________________
7. (4 points) (Choose the most correct of the following answers for each question)
a.
b.
c.
d.
e.
f.
g.
h.
i.
The second thoracic segment is transformed into a third thoracic segment.
All of the structures in the animal develop into head structures.
The animal lacks a normal head.
The third thoracic segment is transformed into the second thoracic segment.
All segments in the embryo develop as second thoracic segments.
The animal lacks a normal tail.
The flies go to Duke, because they cannot tell their heads from their tails.
All segments in the embryo develop as third thoracic segments.
The embryo is normal
What happens to embryonic development:
If an embryo contains no Bicoid protein?: _____________
If all nuclei in an embryo contain high levels of Bicoid protein? _________________
If an embryo completely lacks Ultrabithorax protein? ______________________
If an embryo expresses normal levels of Ultrabithorax protein in T3 and A1? _________________
8. (2 points) Assume that Hunchback, one of the gap genes, is normally expressed in the segments
that make up the head.
(Circle one) Is it likely to be turned ON or OFF by high levels of bicoid?
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(Circle one) In a Hunchback homozygous mutant embryo,
a.
b.
c.
c.
d.
e.
f.
The second abdominal segment is transformed into the first abdominal segment.
Development proceeds normally.
All segments are transformed into head segments.
All segments are transformed into second abdominal segments.
The second through seventh abdominal segments are missing.
All segments are transformed into eighth abdominal segments.
The head segments are missing.
9. (2 points) C. elegans lin-12 encodes a protein related to which fly protein?
_______________
10. The following four true-or-false questions are worth 5 points in total. Mark each as T or F and
for any that is/are false, indicate briefly why in the space below.
a. T F Levels of fruit fly Bicoid are highest at the tail end of the embryo.
b. T F All neural cells arise from a single lineage in the nematode.
c. T F All germ cells arise from a single lineage in the nematode.
d. T F Mutations in ced-3 and ced-4 eliminate all programmed cell death.
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11. (1 point; pick the best choice) By the current model, which of the following cells must express
on their cell surface the receptor for the anchor cell signal?
A. The anchor cell.
D. The gonadal cells.
B. The centralmost vulval precursor cell.
E. The central three vulval precursor cells.
C. The outside three vulval precursor cells.
F. All six vulval precursor cells.
12. (2 points) White-spotting mutations affect the blood system, the germ cells, and melanocytes.
What do all of these tissues have in common that makes them targets of this mutation?
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(Circle one) Which cell type expresses the product of the Steel gene?
Blood precursor cells // bone marrow stromal cells
(Circle one) Which cell type expresses the product of the White-spotting gene?
Blood precursor cells // bone marrow stromal cells
13. (2 points) When doing the "knockout" of Wnt1, among the progeny of the original mosaic
founder were mice heterozygous for the mutant gene (i.e., with one mutant copy of Wnt1 and one
wild-type copy). If a heterozygous male was crossed to a heterozygous female sister, what fraction
of their progeny will show the mutant phenotype (assume Wnt1 is recessive)?
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NAME____________________________________
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14. The following six true-or-false questions are worth 8 points in total. Mark each as T or F and
for any that is/are false, indicate briefly why in the space below.
a. T F Human eggs implant in the uterus just prior to fertilization.
b. T F The mouse is scientists favorite model for studying mammalian development.
c. T F Steel mutant cells can be rescued by wild-type neighbors.
d. T F White spotting mutant cells can be rescued by wild-type neighbors.
e. T F The mouse wingless homolog wnt-1 is required for continued expression of the mouse
f. T F Fruit fly eyeless is related to the mouse Pax gene small eye.
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15. (10 points) The diagram shows the cell fates chosen by different cells of the vulval equivalence
group in a wild-type worm. How many 1° cells, now many 2° cells, and how many 3° cells will be
made in the cases listed below? Hint: in wild-type (total =six) the answer is
1°
_____1_____
2°
_____2_______
3°
______3______
anchor
cell
gonad
3° cell
3° cell
2° cell
1° cell
2° cell
Normal
hypoderm
= skin
3° cell
Normal
hypoderm
= skin
Make vulva
In a mutant in which the gonad is ablated but the anchor cell remains (total =six)
1°
____________
2°
_____________
3°
_____________
In a worm homozygous mutant for the ras G-protein which is downstream of the receptor for the
anchor cell signal (total=six)
1°
____________
2°
_____________
3°
_____________
In a mutant homozygous mutant for the worm EGF receptor, which is the receptor for the anchor cell
signal (total=six)
1°
____________
2°
_____________
3°
_____________
In an animal in which both the anchor cell and the outside three vulval precursor cells were killed
with a laser beam (total =3)
1°
____________
2°
_____________
4
3°
_____________
en
NAME____________________________________
In an animal which is mutant for lin-12 and in which all vulval precursor cells are genetically
engineered to make high levels of the anchor cell signal (total =6)
1°
____________
2°
_____________
3°
_____________
16. (8 points) You are "knocking-out" wnt1.
The ES cell line which is crucial for this procedure was derived from what source?
_______________
These cells differ from those of most other cultured cells in a way which is critical for this procedure;
what can they do that most cultured cells cannot?
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You add to these cells cloned DNA carrying the wnt1 gene. You modified the wnt1 gene by adding
a second gene in the middle of it. From what group of organisms was the second gene originally
derived? ___________________________________________
Most cells do not incorporate the second gene into their own DNA-- only a very small percentage do
so. How do you select these cells? ___________________________________________________
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Having a pure population of cells that are heterozygous mutant, what is your next step (the very next
step, not the whole process!)?
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17. (4 points; choose the best answer-- use each answer only once, and pick a property of that cell,
not its descendents) We discussed how virtually all of the properties of cancer cells are also
possessed by normal cells. Choose from the list ONE normal cell type that has the listed cell
property:
Divides indefinitely without differentiating: ___________________
Migrates to a new cellular location: ____________________
Divides rapidly even though in contact with neighbors: ___________________
Can penetrate the walls of blood vessels and thus move to distant locations: _________________
A.
B.
C.
D.
E.
Skin cells
Bone marrow stem cells.
Kidney cells.
Neurons of the adult brain.
T lymphocytes of the immune system.
F.
G.
H.
I.
Neural crest cells.
Preblastoderm embryonic cells.
Ectoderm.
Liver cells.
18. The following four true-or-false questions are worth 5 points in total. Mark each as T or F and
for any that is/are false, indicate briefly why in the space below.
a. T F Metastatic tumors generally gain the ability to digest and thus penetrate the basal lamina.
b. T F Activation of the Src kinase stimulates skin cells to migrate.
c. T F Metastatic tumors generally lose expression or function of integrins.
d. T F Retroviral activation of the mouse wingless homolog Wnt-1 can cause breast cancer in
mice.
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19. (2 points- fill in the blanks) choose the correct genotype from among those listed:
A. + / +
B. Rbmutant / +
C. Rbmutant / Rbmutant
A kidney cell from a normal individual? ___________
A cell in a sporadic retinoblastoma tumor that arose in a normal individual? ___________
A kidney cell from an individual with a familial predisposition to retinoblastoma? _________
A retinoblastoma tumor cell from an individual with a familial predisposition to retinoblastoma?
_____
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(One point: Circle one) The cell biological function of the normal Retinoblastoma protein is to:
A. Repair damaged DNA.
C. Phosphorylate integrins, promoting cell motility.
B. Turn on genes required for cell proliferation. D. Turn off genes required for cell proliferation.
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20. (7 points) Skin cells normally proliferate at a slow rate in the body, replacing those lost due to
normal attrition. When the skin is wounded, what happens to the cell proliferation rate of skin cells?
(Choose ONE)
It increases
/
It remains the same
/
It decreases.
When wounded, skin cells are exposed to PDGF. What cell type makes PDGF? ____________
What cell type has cell surface receptors for PDGF? __________________
Imagine two different types of mutation in the PDGF receptor tyrosine kinase. Mutation 1 (PDGFRACTIVATED) renders it constitutively active. Mutation 2 (PDGFR-INACTIVE) kills the normal
function. Normal PDGF receptor is designated +.
What would be the rate of cell proliferation in skin cells of the following genotypes, in the absence
and presence of PDGF? In each blank, fill in the rate of proliferation, either SLOW or FAST :
Absence of PDGF
Presence of PDGF
+ / +
_____________
_____________
PDGFR-ACTIVATED / +
_____________
_____________
PDGFR-ACTIVATED / PDGFR-ACTIVATED
_____________
_____________
PDGFR-INACTIVE / PDGFR-INACTIVE
_____________
_____________
21. (3 points) If a person suffers from Xeroderma pigmentosum, they are excessively sensitive to a
particular mutagen. Which one? _______________ What biochemical/cell biological process is
impaired in these individuals? _______________________________ The incidence of which
disease
is thus increased in these individuals? ________________________
22. (2 points) The p53 protein is often called the "guardian of the genome". It carries out this role
by acting as part of a checkpoint in the cell cycle. Choose from the list the most likely immediate
response of the following cells if DNA is damaged:
Normal (i.e., wild-type) cell
________
Cell which lacks p53 protein
A. Metastasize to a distant place in the body.
B. Halt the cell cycle until the DNA is repaired.
________
C. Lose contact inhibition of growth.
D. Continue the cell cycle without halt.
I certify that I have performed my work on this examination in full conformity with the provisions of
the Honor Code.
Signature___________________________________
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