Question 1

Which of the groups of early developmental genes in Drosophila act across segment boundaries to produce parasegments?

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Question 2

Cell signaling during much of C. elegans development occurs along concentration gradients. What kind of signaling does this represent?

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Question 3

The maternal effect bicoid protein is a transcription factor that binds to the promoter of a zygotic gene to activate its expression. What is this second gene?

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Question 4

The establishment of the axes of the body plan occurs during which stage of Drosophila development?

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Question 5

Homeotic genes in virtually all animals are said to show colinearity between the spatial arrangement of the tissues they act on as well as what other feature?

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Question 6

In the development of C. elegans, an embryo of 1090 cells then loses 131 cells. This is an example of what process?

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Question 7

Holoprosencephaly is a highly variable condition in mammals, including humans. Its effects range from an absence of brain areas, mid-face disorders, and cyclopia to slight dental abnormalities. One form, HPE3, is caused by Shh mutations. Familial cases are inherited as dominants. Which of the following do you expect?
A)HPE3 is actually a multigene complex.
B)Each type of malformation is due to a different HPE3 allele.
C)HPE3 expression is modified by genetic background.
D)HPE3 individuals also share a common environmental exposure.
E)All mutations in Shh that result in HPE3 are due to frameshifts.

Accepted Answer

The fact that Holoprosencephaly is highly variable suggests that the phenotype is modified by genetic background. As it is inherited as a dominant, it is unlikely that it is a multigene complex, and there is no evidence to suggest that each type of malformation is due to a different allele. There is also no evidence that HPE3 individuals share a common environmental exposure. In addition, while frameshift mutations can certainly cause disease, there is no information provided to suggest that all Shh mutations that result in HPE3 are due to frameshifts.

Question 8

What characteristic of a cellular blastoderm in Drosophila embryogenesis distinguishes it from the syncytial blastoderm?

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Question 9

Certain mutations in non-Hox genes actually produce homeotic mutants due to a failure to modulate chromatin acetylation appropriately. This influence on cellular "memory" is called what?

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Question 10

A highly conserved protein domain of 60 amino acids is found in a large number of animals. This domain allows the proteins in question to bind to what?

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Question 11

Flower homoeotic genes encode: __________.
A)MADS box genes
B)homeobox genes
C)pair-rule genes
D)housekeeping genes
E)morphogen genes

Accepted Answer

Flower homoeotic genes encode MADS box genes, which are involved in determining the identity of floral organs. Homoeotic genes are responsible for defining the identity of each segment in the floral meristem.

Question 12

Cell autonomous genes affect only those cells in which they are expressed. Which group of early developmental genes are not cell autonomous?

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Question 13

What substance, in different concentrations, directs developmental fates?

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Question 14

The Antennapedia complex and the bithorax complex of genes all encode transcription factors that have a 180-bp DNA-binding domain. What is this domain called?

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Question 15

A homeotic mutant flower has an arrangement (from outside in)of carpels, stamens, stamens, carpels instead of the usual sepal, petals, stamens, carpels. In general, Class A genes specify sepals, Class A and B genes specify petals, Class B and C genes specify stamens, and Class C specifies carpels. This mutant must therefore have a mutation in __________.
A)a Class A gene
B)a Class B gene
C)a Class C gene
D)both A and B
E)both B and C

Accepted Answer

The mutant flower has carpels where there should be sepals and petals, indicating a loss of Class A gene function, which is responsible for specifying sepals and, together with Class B, for specifying petals.

Question 16

What term describes the process by which a cell acquires a certain fate from its neighboring cell?

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Question 17

During the evolution of development in animals, it is found that many regulatory genes have been co-opted for the development of different structures, such as limbs or digits. This is an example of what current area of research?

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Question 18

Which group of genes in Drosophila embryos must be mutated if the result is elimination of a significantly sized, contiguous region of segmentation?

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Question 19

An embryonic stem cell has the potential to differentiate into any cell or tissue type. Is it differentiated, pluripotent, or totipotent?

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Question 20

If a cell from the blastoderm of the Drosophila embryo is committed to form part of an abdominal segment of the adult, such as the sixth one, and this cell is transplanted into the thorax-committed region of another embryo, will it develop properties of a thoracic or an abdominal segment?

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Quiz 20: Developmental Genetics