BIO 349 Developmental Biology (K. Kalthoff)

Exams Summer 1997

First Midterm Exam (23 July 1997)

EXCHANGE WORDS (Maximum 2 points each)

The following statements are erroneous. However, each one can be corrected by exchanging (swapping) two single words. Circle these two words within each statement. A hyphenated word counts as one word.

1./2. Meroblastic cleavage is characteristic of telolecithal and centrolecithal yolk, which contain too much eggs to be cleaved completely.

3./4. The gray cortex of the amphibian egg arises when the egg crescent rotates toward the sperm entry point.

MULTIPLE CHOICE (1 point each)

In the following questions or statements, circle the letter associated with the one answer or version of the statement that you consider to be the correct one.

5. The onset of the midblastula transition is controlled by
a. centrioles
b. contractile rings
c. localized cytoplasmic determinants
d. none of the above is correct

6. The supply of M phase-promoting factor (MPF) controls
a. the arrest of growing amphibian oocytes in prophase I of meiosis
b. the arrest of mature amphibian oocytes in metaphase II of meiosis
c. the mid-blastula transition in Drosophila
d. all of the above are correct

7. Discoidal cleavage is characteristic of
a. amphibians
b. insects
c. mammals
d. none of the above is correct

8. Cells are considered to be determined when
a. their potency equals their fate
b. their potency is larger than their fate
c. both of the above are correct
d. none of the above is correct

9. A compartment in insect epidermis is
a. defined by clonal restriction lines
b. filled with a polyclone
c. both of the above are correct
d. none of the above is correct

10. Nuclei from frog kidney, upon transplantation into newt oocytes, support the synthesis of
a. frog kidney-specific proteins
b. frog oocyte-specific proteins
c. newt kidney-specific proteins
d. none of the above is correct

11. Dorsal vegetal blastomeres of frog embryos at the 32/64-cell stage will form
a. the Nieuwkoop center
b. the Spemann organizer
c. both of the above are correct
d. none of the above is correct

FILL IN THE BLANKS

Complete each of the following sentences by inserting one word into each blank space so that a scientifically and linguistically correct statement results. A hyphenated word counts as one word.

12./13. The midblastula transition (MBT) is thought to be triggered when embryonic cells reach a certain _______________ ratio. In accord with this hypothesis, MBT occurs one cell cycle _______________ than normal if half of the egg cytoplasm is removed after fertilization.

14./15. The phenomenon of transdetermination was first observed in Drosophila _______________ discs that had been forced through many extra rounds of cell _______________.

16./17. Along with _______________ localization, _______________ is the most common way of cell determination.

PICK THE ODD STATEMENT (1 point each)

For the following questions, either three of the statements are correct and one is false, or three are false and one is correct. Pick out the one odd statement, be it correct or false, and circle the respective letter.

18. Clonal Analysis
a. A cell clone is defined as all cells within a compartment.
b. A cell clone can be labeled by somatic crossover.
c. A cell clone always consists of cells that are differentiated in the same way.
d All cells of a clone divide in synchrony.

19. Genomic Equivalence
a. Differentiated plant cells have been shown to be totipotent.
b. The cloned sheep "Dolly" was obtained by transferring the nucleus of a plant cell into a sheep egg.
c. In animals, each cell retains only those genes that it needs according to its fate.
d. All spermatozoa produced by a given mammalian male are genetically equivalent.

20. Mesoderm Induction in Amphibians
a. The potency of equatorial (marginal) blastula cells to form mesodermal structures is acquired gradually during cleavage.
b. Animal cells induce their vegetal neighbors to form mesoderm.
c. Dorsal vegetal blastomeres induces neighboring equatorial cells to form notochord.
d. Dorsal equatorial cells induce their lateral neighbors to form intermediate mesoderm.

21-30. SHORT ESSAY (Max. 10 pts.) Mammalian Gametogenesis

Outline four differences between spermatogenesis and oogenesis in mammals. Relate each difference to the overall functions of egg and sperm.

31-40. SHORT ESSAY (Max. 10 pts.) Slow Block to Polyspermy

A. Outline briefly the process of cortical reaction and explain in an overall way why the cortical reaction is called a slow block to polyspermy.
B. Describe three molecular mechanisms that occur as part of the cortical reaction and that - each by itself - inhibit fertilization of the egg by multiple sperm.
C. State a general principle in development that is illustrated by the mechanisms discussed in part B.

41-50. SHORT ESSAY (Max. 10 pts.) Rescue Criterion for Localized Cytoplasmic Determinants

A. Outline the "rescue" operation used to demonstrate the existence of localized cytoplasmic determinants in animal eggs. Remember the control that must be done to make this criterion valid.
B. Which two types of recipients have been used for the rescue operation?
C. Describe one example to illustrate the use of the rescue criterion.


Second Midterm Exam (6 August, 1997)

MULTIPLE CHOICE (1 point each)

In the following questions or statements, circle the letter associated with the one answer or version of the statement that you consider to be correct.

1. Additional notochord transplanted to the side of a closing neural tube induces the formation of extra
a. floor plate
b. alar plate
c. both of the above are correct
d. none of the above is correct

2. Which of the following structures is not derived from neural crest cells
a. adrenal medulla
b. basal plate
c. pigment cells
d. sympathetic ganglia

3. Differential gene expression can be shown directly by
a. in situ hybridization of a labeled cDNA probe to histological sections
b. immunostaining
c. both of the above are correct
d. none of the above is correct

FILL IN THE BLANKS

Complete each of the following sentences by inserting one word into each blank space so that a scientifically and linguistically correct statement results. A hyphenated word counts as one word.

4/5. All vertebrates look very _______________ after organogenesis; this stage is therefore known as the _______________ stage of vertebrates.

6/7. Before and after oocyte maturation in mammals, there is a general _______________ between the _______________ activity of a mRNA and its polyadenylation.

PICK THE ODD STATEMENT (1 point each)

For the following questions, either three of the statements are correct and one is false, or three are false and one is correct. Pick out the one odd statement, be it correct or false, and circle the respective letter.

8. Eukaryotic Gene Structure
a. The transcribed region of most eukaryotic genes contains introns and exons.
b. The TATA box is an enhancer sequence.
c. The introns are spliced out of the genomic DNA before transcription.
d. Each gene has only one promoter.

9. Positional Information
a. According to Wolpert, the cells of an embryonic field receive positional values with respect to certain reference points.
b. Positional values are interpreted by cells according to their genotype.
c. Various positional values may be conferred by a single morphogen.
d. Once specified, positional information does never change.

10. Morphogen Gradients
a. A morphogen gradient specifies a range of positional values to a field.
b. Morphogen gradients follow the shortest intercalation rule.
c. Morphogen gradients may confer size invariance to a field.
d. Different morphogen concentrations may elicit different gene activities.

11-20.MATCH UP (maximum 10 points)

Below are a list of embryonic structures (1-10) and a list of cellular and epithelial movements (a-h). Match up by entering one appropriate letter in the space behind each number. If an embryonic structures shows more than one type of cellular or epithelial movement, enter the letter for the most significant movement. Note that some epithelial movements may not be carried out by any of the embryonic structures listed. Each correct entry earns a one-point credit. Maximum credit for this entire question is ten points.

1.___ frog gastrula animal cap

2.___ frog gastrula bottle cells

3.___ frog gastrula deep zone (head mesoderm)

4.___ frog gastrula non-involuting marginal zone

5.___ frog gastrula vegetal base

6.___ frog neural plate

7.___ mammalian sclerotome

8.___ neural crest cells after neurulation

9.___ sea urchin achenteron

10.___ sea urchin vegetal plate

a. convergent extension
b. delamination
c. epiboly
d. ingression
e. invagination
f. involution
g. migration
h. passive movements

21-30. SHORT ESSAY (Max. 10 pts.) Organizer Experiment

A. Describe the organizer experiment of Spemann and Mangold, including
a. the experimental procedure,
b. the results, including which structures were formed by the graft and which by the host, and how the experimentors could tell
c. the major conclusions.
B. How did the age of the donor embryo affect the result of the experiment, and how do you interpret this causal relationship?

31-40. SHORT ESSAY (Max. 10 pts.) Transgenic Cells

A. Define what a genetically transformed cell is.
B. Outline a general procedure to create genetically transformed cells using a selectable marker.
C. How can cell transformation be used to create the equivalent of a loss-of-function allele for a gene?

41-50. SHORT ESSAY (Max. 10 pts.) RNA Splicing in Drosophila Sex Differentiation

A. Outline the genetic hierarchy that controls somatic sex differentiation in Drosophila.
B. Name or mark in particular the two pre-mRNAs that interact with Sexlethal protein according to the cascade outlined in part (A).
C. Describe the nature of the interactions through which Sexlethal protein controls the processing of the two pre-mRNAs named in part (B).


Final Exam (16 August 1997)

MATCH UP (Maximum 10 points)

The following are lists of Drosophila gene names (1-10) and their descriptions (a-j). Match up by entering the appropriate letters in the spaces behind the numbers. The correct answer shows a one-to-one correlation.

1. ______ Antennapedia+

2. ______ bicoid+

3. ______ engrailed+

4. ______ fushi tarazu+

5. ______ hairy+

6. ______ hunchback+

7. ______ Krüppel+

8. ______ sisterless+

9. ______ transformer+

10. ______ Ultrabithorax+

a. controls sexual development, encodes RNA-binding protein
b. controls sexual development, encodes transcription factor
c. gap gene, expressed in anterior and posterior domain
d. gap gene; expressed in middle band
e. homeotic gene; directs leg formation
f. homeotic gene; directs metathorax formation
g. maternally expressed gene; directs anterior body pattern
h. primary pair rule gene
i. secondary pair rule gene
j. segment polarity gene; expressed in posterior compartment of each segment

EXCHANGE WORDS (Maximum 2 points each)

The following statements are erroneous. However, each one can be corrected by exchanging (swapping) two single words. Circle these two words within each statement. A hyphenated word counts as one word.

11/12.Atavisms are reappearances of phylogenetically older traits in normal development whereas recapitulations are abnormal reappearances of ancient features.

13/14.Many useful fusion genes combine the eukaryotic region of a regulatory gene with the transcribed region of a bacterial gene.

15/16.In surf clam oocytes, certain mRNAs are stored in polysomes while other mRNAs are translated in subribosomal RNP particles.

MULTIPLE CHOICE (1 point each)

In the following questions or statements, circle the letter associated with the one answer or version of the statement that you consider to be the correct one.

17. Which of the following structures are derived from neural crest cells?
a. dorsal root ganglia
b. pigment cells
c. both of the above
d. none of the above

18. Which of the following processes is regulated by RNA-binding proteins?
a. splicing of pre-mRNA
b. RNA translation
c. RNA degradation
d. all of the above

19. Embryonic cells are determined by
a. localized cytoplasmic components
b. induction
c. both of the above are correct
d. none of the above is correct

20. The mammalian sex hormone, testosterone, is produced by
a. interstitial cells (Leydig cells) of the testis
b. ovarian theca cells
c. both of the above are correct
d. none of the above is correct

FILL IN THE BLANKS

Complete each of the following sentences by inserting one word into each blank space so that a scientifically and linguistically correct statement results. A hyphenated word counts as one word.

21/22. According to the compartment hypothesis, each epidermal compartment is characterized by a unique _______________ of active selector genes, which affect cell surfaces so as to prevent the _______________ of cells from neighboring compartments.

23/24. Mammalian XY indidividuals without a functional _______________ receptor gene develop as females but lack all _______________ duct derivatives.

25/26. While proto-oncogenes have been discovered through their _______________ alleles, tumor suppressor genes were recognized after analysis of their _______________ alleles.

PICK THE ODD STATEMENT (1 point each)

For the following questions, either three of the statements are correct and one is false, or three are false and one is correct. Pick out the one odd statement, be it correct or false, and circle the respective letter.

27. Phylotypic Stage
a. All vertebrates are very similar to one another after organogenesis (phylotypic stage).
b. Among adult vertebrates, mammals remain closest to the phylotypic organization.
c. The secondary jaw joint of mammals is part of the phylotypic organization of vertebrates.
d. Multiple aortic arches are normal in adult mammals but occur only as atavisms in fish.

28. Control of Transcription
a. Transcription of eukaryotic genes is controlled by promoter and enhancer elements.
b. Promoters and enhancers are bound specifically by transcription factors.
c. All cells of an organism contain the same mixture of transcription factors.
d. Transcription factors position RNA polymerase at the transcription startpoint.

29. Protein Synthesis during Spermiogenesis
a. The sperm nucleus is compacted as histone proteins are replaced with protamine.
b. Protamine mRNA is immediately translated in the developing sperm.
c. Protamine mRNA has a longer half-life than most other mRNAs in the developing sperm.
d. The signals for the timing of protamine mRNA translation and breakdown are contained in the trailer region.

30. Compartments
a. Compartments have been defined in insect epidermis by clonal restriction lines.
b. All cells within a compartment share the same positional values.
c. Some compartments coincide with the realms of maternal effect genes.
d. Each compartment is filled by one cell clone.

31-40.SHORT ESSAY (max. 10 points) Principle of Default Programs
A. State the principle of default programs in development.
B. Illustate the principle using two examples.

41-50.SHORT ESSAY (max. 10 points) Shell Coiling in Lymnea peregra
A. What is a maternal effect mutation?
B. As an example, outline the inheritance of dextral and sinistral shell coiling in the snail Lymnea peregra. Diagram reciprocal crossings between dextral (+/+) and sinistral (s/s) individuals as parents (P generation). (Remember that snails are hermaphrodites, and that the dextral allele is dominant over the sinistral allele.) Show the genotypes occurring in the offspring (F1 generation) of each crossing and their phenotypes.
C. At which stage of development can the dextral and sinistral phenotypes first be distinguished? Characterize the difference between the two phenotypes at this stage.
D. Outline briefly the connection between the earliest phenotypical difference, as characterized in part C, and the eventual difference in shell coiling.

51-60.SHORT ESSAY (Max. 10 pts.) Cell Fate, Potency, and Determination
A. What is the fate of embryonic cells, and how is it revealed experimentally?
B. What is the potency of embryonic cells, and how is it tested experimentally?
C. Define cell determination in terms of fate and potency.

61-70.SHORT ESSAY (Max. 10 pts.) Drosophila Mutant and Wolpert's Concept of Pattern Formation
Background information: A Drosophila homeotic mutant showing a replacement of antenna with leg was caused by a chromosomal inversion, which brought a homeotic gene near the promoter of an unrelated gene. However, the connection between the homeotic gene and the unrelated promoter was shaky, so that the homeotic gene was active in some patches of cells but not in others.
A. Name the homeotic gene that could have caused this phenotype.
B. Name the body region where this homeotic gene is most active in wild-type flies.
C. Describe - in some detail - and preferably with the aid of a diagram - the results of the homeotic gene's patchwise activity in the imaginal disk that normally forms antenna.
D. Interpret the observations described in part C in terms of Wolpert's concept of pattern formation.

71-80.SHORT ESSAY (Max. 10 pts.) Homeotic Genes and Hox Genes
Describe four features that Drosophila homeotic genes and mouse Hox genes have in common. Outline in a few sentences how each feature was discovered.


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