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Flashcards in MBB 142 lec Drosophila Deck (121)
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1
Q

The best understood of all developmental model systems

A

Drosophila

2
Q

Drosophila hatches from the egg as a/an?

A

Larva

3
Q

Two axes which define early Drosophila body patterning

A

Antero-posterior and Dorso-ventral axes

4
Q

The four regions that the dorso-ventral axis of Drosophila is divided into (from ventral to dorsal)

A

Mesoderm, Neuroectoderm/ Ventral ectoderm, Dorsal ectoderm, Amnioserosa

5
Q

What is the amnioserosa?

A

An extraembryonic membrane that is sloughed off during development

6
Q

The region/s that the ventral ectoderm will develop into

A

Ventral epidermis and Neural tissue

7
Q

The region/s that the dorsal ectoderm will develop into

A

Epithelium

8
Q

The regions that the antero-posterior axis will develop into (3)

A

Head, Thorax, and Abdomen

9
Q

Number of parasegments

A

14

10
Q

Number of thoracic and abdominal segments

A

3 and 8

11
Q

Distinguishing characteristics of the segments (2)

A

Denticles and Bristles

12
Q

Specialized structure at the posterior end of the larva

A

Telson

13
Q

Specialized structure at the anterior end of the larva

A

Acron

14
Q

Process of change from larva to adult

A

Metamorphosis

15
Q

Group of cells set aside in the embryo that eventually give rise to adult structures, such as the wings and legs

A

Imaginal discs

16
Q

Does the antero-posterior axis finish developing first before development of the dorso-ventral axis begins?

A

No, they occur simultaneously

17
Q

The early multinucleate stage in Drosophila development

A

Syncytial blastoderm

18
Q

What is the third dimension in the development of Drosophila, and when does this dimension form?

A

The proximal-distal axis, which forms during gastrulation

19
Q

These genes set up the body axes

A

Maternal genes

20
Q

Those genes which are required for subsequent development of Drosophila at later developmental stages

A

Zygotic genes

21
Q

The four main classes of zygotic genes

A

Gap genes, Pair-rule genes, Segment polarity genes, and Homeotic/Selector genes

22
Q

Selector genes depend on which sets of zygotic genes?

A

Gap genes, and Pair-rule genes

23
Q

Three classes of maternal genes that define the antero-posterior axis

A

Those that affect anterior regions, posterior regions, and the terminal regions

24
Q

T/F: Maternal genes establish differences in the antero-posterior axis after fertilization

A

F

25
Q

Mutations that, when present in the mother, do not affect her but affects her progeny

A

Maternal-effect mutations

26
Q

T/F: Bicoid gene expression affect nanos gene expression

A

F, they work independently

27
Q

Mutations in what maternal gene will lead to the absence of the acron and telson?

A

Torso

28
Q

From what germ layer does the ovary of the mother derive from?

A

Mesoderm

29
Q

Where in the unfertilized egg is bicoid mRNA localized?

A

Anterior end

30
Q

When is bicoid mRNA translated?

A

At fertilization

31
Q

If a normal fertilized egg has parts A, B, C, D, and E (from anterior to posterior), and a mutant bicoid fertilized egg was injected with external bicoid at site C. What will be the arrangement of parts in the injected bicoid mutant? Assume that a larva can only have 5 parts in its antero-posterior axis.

A

C, B, A, B, C

32
Q

What is the maternal gene that encodes for a protein that relocates bicoid mRNA to the anterior end of an egg?

A

Exuperantia

33
Q

What is the half-life of the bicoid protein?

A

30 minutes

34
Q

T/F: For proper patterning of the antero-posterior axis, a functioning bicoid gradient is enough.

A

F, both ends must be specified

35
Q

This group of maternal genes control the posterior development of the Drosophila body plan

A

Posterior group genes

36
Q

The development of what structure is impeded by mutations in posterior group genes?

A

Abdomen

37
Q

This maternal gene product localizes nanos mRNA to the posterior end of the fertilized egg

A

Oskar

38
Q

This maternal gene product specifies the posterior germ plasm, which eventually gives rise to the germ cells of Drosophila

A

Oskar

39
Q

Nanos is present in the unfertilized egg as what?

A

mRNA

40
Q

What maternal gene product/s makes a morphogen gradient with its highest level at the posterior end?

A

Nanos and Caudal

41
Q

The expression of what (specify source) is inhibited by nanos protein?

A

Maternal hunchback

42
Q

What causes the translation of zygotic hunchback?

A

Bicoid

43
Q

Nanos prevents the expression of maternal hunchback by binding to the complex of? (2)

A

Maternal hunchback mRNA and Pumilio

44
Q

If a maternal hunchback mutant were to be created, but somehow nanos expression was disturbed in the process, will the egg develop to be normal still? Why?

A

Yes, because the only function of nanos is to suppress maternal hunchback expression

45
Q

Where is caudal mRNA initially found?

A

Uniformly distributed in the egg

46
Q

What inhibits caudal protein expression?

A

Bicoid

47
Q

Does the development of the two terminal regions utilize separate pathways?

A

No, both use the same pathway

48
Q

What is the receptor protein that is important in specifying the terminal regions of the egg?

A

Torso

49
Q

What is the ligand of the torso protein?

A

Trunk

50
Q

Before fertilization, where (specify region) is the ligand of torso bound to?

A

The terminal portions of the side of the vitelline envelope facing the egg

51
Q

What do you call the space in between the vitelline envelope and the cell membrane?

A

Perivitelline space

52
Q

What prevents the ligand of torso from dispersing to the non-terminal regions of the egg?

A

The low amount of the ligand and the fact that most of it gets bound by torso at the terminal leads to a lack of dispersal.

53
Q

What is the receptor type of the torso protein?

A

Receptor tyrosine kinase

54
Q

What secretes the spatzle protein into the vitelline space?

A

Follicle cells

55
Q

Where is pipe mRNA transcribed in the vitelline space by follicle cells?

A

Ventral 1/3 of the egg

56
Q

What other maternal genes, aside from pipe, are important in the processing of spatzle? (3)

A

Easter, Nudel, and Windbeutel

57
Q

What receptor accepts a particular form of spatzle as its ligand?

A

Toll

58
Q

What is the form of spatzle accepted by its ligand?

A

Fragmented form

59
Q

In what regions of the egg is Toll located in the plasma membrane?

A

Everywhere

60
Q

What is the original location of the dorsal protein?

A

At the cytosolic periphery of the egg

61
Q

T/F: The dorsal protein acts as both a morphogen and a transcription factor.

A

T

62
Q

The term used to describe embryos in which no ventral structures develop.

A

Dorsalized

63
Q

What prevents the dorsal protein from prematurely entering the nuclei?

A

Cactus

64
Q

What are the human homologs of dorsal and cactus proteins?

A

NF-kB, and I-kB

65
Q

Give the two maternal gene products that help in the transduction of the signal by Toll to allow the entry of dorsal protein inside the nuclei of the syncytial blastoderm.

A

Tube and Pelle

66
Q

What is the effect of the signal from the activated Toll protein that allows for nuclear dorsal protein entry?

A

Degradation of bound cactus protein

67
Q

What is the structure in which the original stem cell (that gives rise to the oocyte and nurse cells) is contained?

A

Germarium

68
Q

What do you call the outgrowths of the germarium containing the developing oocyte?

A

Egg chamber

69
Q

How many times does the original stem cell divide to give rise to the oocyte as well as its nurse cells?

A

4 times

70
Q

What allows the nurse cells to provide to the oocyte the various maternal mRNAs that it needs for development?

A

Cytoplasmic bridges

71
Q

What cells are mainly responsible for the patterning of the developing oocyte?

A

Follicle cells

72
Q

What secretes the vitelline envelope, as well as the chorion of the Drosophila egg?

A

Follicle cells

73
Q

First visible sign of antero-posterior axis development in the egg

A

Movement of egg towards one end of the egg chamber

74
Q

What facilitates the attachment of the oocyte to the follicle cells?

A

E-cadherin

75
Q

What facilitates the inductive signal produced by the oocyte to the follicle cells it contacts?

A

Gurken

76
Q

What family does the gurken protein belong to?

A

TGF-alpha family of proteins

77
Q

The receptor for the gurken protein is located where?

A

On the follicle cells contacting the oocyte

78
Q

What is the receptor for the gurken protein?

A

Torpedo

79
Q

What is the kind of receptor for the gurken protein receptor?

A

Receptor tyrosine kinase

80
Q

What is the response of the egg upon receiving the signal from the follicle cells due to activation of torpedo?

A

Reorganization of microtubules on the antero-posterior axis

81
Q

Where is bicoid mRNA produced?

A

By the nurse cells on the anterior portion of the egg

82
Q

Which occurs first, the organization of the antero-posterior axis or the dorso-ventral axis, at least in the developing oocyte?

A

Antero-posterior axis is first

83
Q

How many times is gurken protein expression activated during the determination of the axes of the developing oocyte?

A

Two times, one during antero-posterior axis determination, and another time during dorso-ventral axis determination

84
Q

Most of the zygotic genes encode what type of proteins?

A

Transcription factors

85
Q

What are the different regions present in the dorso-ventral axis, and what genes are expressed in each?

A

Mesoderm - Twist and Snail
Between the mesoderm and the neuroectoderm - Single-minded)
Ventral ectoderm/ Neuroectoderm - Rhomboid
Dorsal ectoderm - Tolloid and Decapentaplegic
Amnioserosa - Zerknullt

86
Q

The expression of what genes is activated by high amounts of dorsal protein?

A

Twist and Snail

87
Q

What activates rhomboid gene expression? What represses it?

A

Low amounts of dorsal protein; Snail

88
Q

Are there regions in the fertilized egg in which both twist and decapentaplegic expression is absent? Where would this region most likely be?

A

Yes. It would most likely be at the neuroectoderm.

89
Q

What determines the ventral pattern of early embryo?

A

Decapentaplegic

90
Q

What is the homolog of decapentaplegic?

A

BMP-4

91
Q

When does the embryo become cellular? (in terms of the development of the dorso-ventral axis)

A

After the establishment of the dorsal protein gradient/ After twist and snail expression

92
Q

Why is sog necessary in the determination of the dorso-ventral axis?

A

It is because decapentaplegic (dpp) is an autoregulator, meaning that is activates its own expression. Sog helps prevent the spread of dpp to the ventral regions by preventing its autoregulatory effect.

93
Q

What are the first genes to be expressed in the antero-posterior axis?

A

Gap genes

94
Q

T/F: Some gap genes do not code for transcription factors, and merely code for proteins that function in the stabilization of parasegmentation.

A

F, all gap genes code for transcription factors.

95
Q

Name five examples of gap genes.

A

Hunchback, Knirps, Giant, Kruppel, and Tailless

96
Q

T/F: The phenotype of gap gene mutants only involves the lack of certain parts of the mutant embryo.

A

F, gap genes are known to have effects other than the determination of the antero-posterior axis.

97
Q

T/F: The multiple regions of giant expression is indicative of an aperiodic pattern of transcription.

A

T

98
Q

Is the embryo a syncytial or cellular blastoderm at the time of gap gene expression?

A

The embryo is still a syncytial blastoderm.

99
Q

The expression of gap genes is controlled by…

A

Bicoid, hunchback, as well as the expression of other gap genes

100
Q

Bicoid is a member of what family of transcriptional activators?

A

Homeodomain family

101
Q

The transposon used to artificially introduce genes in Drosophila

A

P-element

102
Q

The enzyme responsible for the hopping of P-elements from one region of the Drosophila chromosome to another

A

Transposase

103
Q

An exogenous protein that can be used to temporally and spatially control the expression of the inserted genes in Drosophila.

A

GAL4

104
Q

A technique in which a gene is randomly inserted into regions in the chromosome, and leads to the temporal and spatial expression of the inserted gene depending on the promoter and enhancer regions found near the insert site.

A

Enhancer trap

105
Q

Describe the dependence of Kruppel expression on the levels of hunchback protein.

A

Kruppel expression is inhibited by both high and low levels of hunchback expression.

106
Q

Describe the dependence of knirps expression on the levels of hunchback and tailless.

A

Knirps expression is inhibited both by high levels of hunchback, as well as the presence of tailless

107
Q

This is the modules from which segments derive.

A

Parasegments

108
Q

The segments that will fuse to form the head.

A

C1, C2, and C3.

109
Q

First visible signs of segmentation in the embryo.

A

The formation of transient grooves.

110
Q

Each segment is made out of? (in terms of parasegments)

A

The anterior portion of one parasegment, and the posterior portion of the next

111
Q

The parasegments are delimited by the action of what genes?

A

Pair-rule genes

112
Q

T/F: Pair-rule gene expression, as well as gap gene expression, are both periodic in that multiple regions of expression are found in each.

A

F, pair-rule gene expression is periodic, while that of gap genes is aperiodic

113
Q

Does the expression of pair-rule genes depend on the wave-like expression of a corresponding morphogen?

A

No, pair-rule gene expression depends on the combination of particular transcription factors, such as bicoid, hunchback, as well as the gap genes.

114
Q

The boundaries of the second even-skipped gene is determined by…

A

The levels of Kruppel and giant expression

115
Q

Give three examples of pair-rule genes.

A

Even-skipped, Hairy, and Fushi tarazu

116
Q

The expression of fushi tarazu depends on…

A

Expression of primary pair-rule genes, such as even-skipped and hairy

117
Q

The formation of the third parasegment depends on activation of even-skipped by…

A

Expression of bicoid and hunchback above a certain threshold level

118
Q

T/F: Segment polarity genes encode for transcription factors only.

A

F, they encode for a diverse kind of proteins.

119
Q

The segment polarity genes act in a syncytial or cellular environment?

A

Cellular

120
Q

The expression of this gene allows for setting up cell lineage boundaries

A

Engrailed

121
Q

What do you call a gene which confers an identity to specific regions, and so is required to be activated for extended periods of time?

A

Selector genes