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Cell Bio & Developmental Genetics > Minitest 1 - Drosophila Mutants > Flashcards

Minitest 1 - Drosophila Mutants Flashcards

1
Q

Orientation of Drosophila embryos

A
  • dorsal = flat
  • ventral = curved
  • anterior = pointed
  • posterior = blunt
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2
Q

Why is it difficult to identify all different stages?

A

some stages are shorter/longer than others

• embryogenes is fast - it takes only 13 hours from stage 1 to stage 17

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3
Q

What cell type is formed in stage 4?

A

pole cells

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4
Q

4 embryonic stages that are completed by stage 5

A
  • pole cell formation
  • cleavage divisions
  • cellularization
  • blastoderm nuclei migration
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5
Q

Physical features of stage 4

A
  • yolk
  • blastoderm nuclei
  • pole cells
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6
Q

Physical features of stage 5

A
  • blastoderm nuclei
  • yolk
  • visible border margin
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7
Q

Physical features of stage 7

A
  • cephalic furrow

* proctodeal invagination (aka-ish posterior furrow)

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8
Q

Stomodeum vs proctodeal

A

stomodeum –> foregut

proctodeal –> hindgut

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9
Q

Pole cells become incorporated into the

A

posterior midgut and form a pocket visible as a groove

proctodeall invagination

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10
Q

What is the proctodeal invagination?

A
  • a dorsal plate of blastoderm cells that carries the pole cells, tilts inward anteriorly and forms a pocket
  • the pocket now contains the pole cells
  • the pocket is called the proctodeal invagination
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11
Q

“Proctodeum”

A

part of the anal passage

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12
Q

3 folds that are clearly visible at stage 7

A

• cephalic furrow
• anterior furrow
• posterior furrow
(and proctodeal invagination)

  AF   PF   PI CF
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13
Q

Physical features of stage 11

A
  • clypeolabrum
  • mesoderm
  • stomodeal invagination
  • yolk
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14
Q

The … forms the insect’s face

A

clypeolabrum - delimits the lower margin of the face

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15
Q

At stage 11 the … is the innermost layer of the germ band

A

mesoderm

• muscles derive from mesoderm

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16
Q

The stomodeal invagination listed under stage

A

10
• stage 10 lasts for 1h
• onset characterized by the appearance of the stomodeum which eventually gives rise to the foregutand its annexes
• the cells that form the stomodeum are internalized at the anterior ventral side of the embryo - the site of invagination is called the stomodeal invagination

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17
Q

Syncytium

A

a large cell containing multiple scattered nuclei

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18
Q

What do you call the early embryonic stage when cellularization takes place?

A

Blastoderm

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19
Q

The name of the outer egg shell

A

chorion

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20
Q

The name of the inner egg shell

A

vitalline membrane

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21
Q

Type of gene: Hunchback

A
  • maternal effect gene

* gap gene

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22
Q

Type of gene: Kruppel

A

gap gene

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23
Q

Type of gene: Knirps

A

gap gene

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24
Q

type of gene: odd-skipped

A

pair-rule gene

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25
Q

Type of gene: wingless

A

segment polarity gene

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26
Q

Type of gene: patched

A

segment polarity gene

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27
Q

Formation of the dorso-ventral axis

A

Dorsal - the ventral morphogen

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28
Q

Dpp is expressed in

A

the dorsal ectoderm

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29
Q

Twist is expressed in

A

the ventral mesoderm

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30
Q

Hunchback is an

A

anterior morphogen

anterior –> posterior

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31
Q

…required for the formation of the anterior part of the embryo

A

Bicoid AND Hunchback

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32
Q

Hunchback missing

Hunchback cuticle phenotype

A

• still has bicoid –> still has head
• 3 thoracic segments missing
(most anterior structures co-depend on bicoid)
• shorter - only see the abdomen and head
• head involution is incomplete
• fusion of A7 and A8

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33
Q

Head involution

A

during late embryogenesis the head jis folded back into the embryo

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34
Q

In hunchback mutants the dorsal part of the embryo/larva is missing

A

FALSE

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35
Q

In hunchback mutants head involution is affected

A

TRUE

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36
Q

In hunchback mutants abdominal segents 7 and 8 are fused

A

TRUE

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37
Q

In hunchback mutants thoracic segments 1 to 3 are missing

A

TRUE

38
Q

In hunchback mutants denticle belts are dorsally expanded

A

FALSE

39
Q

Gap gene expression patterns are

A
  • extablished by maternal morphogens
  • maintained by mutual repression
  • high levels of Bicoid and Huncback activate Giant
  • low levels of Hunchback activate Kruppel
  • Caudal activates Knirps and Giant
40
Q

High levels of Bicoid and Hunchback activate

A

Giant

bicoid and hunchback = gap genes

41
Q

Low levels of Hunchback activate

A

Kruppel

Hunchback = gap gene

42
Q

Caudal activates

A

Knirps and Giant

43
Q

Kruppel is expressed in the area which will develop into

A

T1 - A5

44
Q

Knirps is expressed in the area which will develop into

A

A2 - A5

45
Q

Kruppel mutant embryos

gap genotypes

A

deletions between T1 and A5

see few abdominal

46
Q

Knirps mutant embryos

gap phenotypes

A

A2 to A5 are affected

47
Q

In Kruppel mutants all abdominal segments are deleted

A

FALSE

48
Q

In Kruppel mutants all thoracic segments are deleted

A

TRUE

49
Q

In Kruppel mutants the segments betwen T1 and A5 are deleted

A

TRUE

50
Q

In Kruppel mutants abdominal segments A1 to A5 are fused

A

FALSE

51
Q

In Kruppel mutants thoracic segments T1 to T3 are fused

A

FALSE

52
Q

In knirps mutants abdominal segments are deleted

A

TRUE

53
Q

In knirps mutants denticle belts are dorsally expanded

A

FALSE

54
Q

In knirps mutants all cells form dorsal cuticle (ie hairs)

A

FALSE

55
Q

In knirps mutants T1 to T3 are missing

A

FALSE

56
Q

In knirps mutants abdominal segments can be fused

A

TRUE

57
Q

The pair-rule gene expression patterns divide the embryo into

A

precursors of the segmental units

58
Q

In odd-skipped mutants

pair-rule

A 
• every other segment is missing
• have 2468 but no 1357
  (thoracic misses even)
• ventral denticles in anterior
• deletion of all or half of the denticle belts in odd-numbered segments
59
Q

In odd-skipped mutants, the denticle belts of … are present

A

denticle belts of

T1, T3, A2, A4, A6, and A8 are present

60
Q

In odd-skipped mutants denticle belts in odd numbered segments can be completely absent

A

TRUE

61
Q

In odd-skipped mutants half of the denticle belts in odd numbered segments can be absent

A

TRUE

62
Q

In odd-skipped mutants even-numbered denticle belts can be completely absent

A

TRUE

63
Q

In odd-skipped mutants the thoracic denticle belts are fused

A

FALSE

64
Q

In odd-skipped mutants abdominal denticle belts are fused

A

FALSE

65
Q

In early embryos, there are different gene expression domains
(Gap –> segment polarity)

A

segment polarity genes
• give 14 stripes (engrailed and wingless)
• anterior –> posterior identity of each segment
get morphogenically visible segments

66
Q

The expression of Wingless and Engrailed is maintained by

A

interactions between the products of these genes

67
Q

Maintenance of wingless and engrailed expression by

A

mutual regulation

68
Q

Wingless mutant

A 
• gradient of expression in segment
• anterior hairs in denticle belt
• remove wingless = smaller
• form naked cuticle --> get only denticle 
(no gap = HAIRY EMBRYO)
69
Q

Wingless and Hedgehog gradients are required for

A

the different fates of the epidermal cells

70
Q

Naked cuticle in area of

A

wingless expression

• fusion of denticle belt

71
Q

In wingless mutant embryos the denticle belts are dorsally expanded

A

FALSE

72
Q

In wingless mutant embryos the first abdominal segment is enlarged

A

FALSE

73
Q

In wingless mutant embryos the denticle belts are fused

A

TRUE

74
Q

In wingless mutant embryos head defects can be observed

A

TRUE

75
Q

In wingless mutant embryos the naked cuticle between denticle belts is reduced or absent

A

TRUE

76
Q

Formation of the dorso-ventral axis requires

A

Dorsal, the ventral morphogen

77
Q

Dorsal is only expressed in the

A

ventral part of the embryo

78
Q

Dorsal protein - wild-type

A

Dorsal in ventral nuclei –> both dorsal and ventral

79
Q

Dorsal protein in all nuclei

A

ventralized embryo

80
Q

Dorsal switches…

A
  • TWIST on in ventral

* DPP off in dorsal

81
Q

Dorsal protein activates and represses different

A

zygotic genes

depending on twist (?) nuclear concentration

82
Q

Genes downstream of Dorsal activate

A

other genes that further subdivide ventral cell fate

83
Q

Dpp cuticle phenotype

A

all structures above the H46 line are absent in the mutant embryos/larvae

84
Q

Dpp mutant - weak phenotype

A

deletions of dorsal-anterior structures

85
Q

Dpp mutant - strong phenotype

A

dorsal expansion of denticle belts up to denticle belts encircling whole embryo

86
Q

Dpp - need dorsal structures, repress –>

A

dorsal structures absent = expanded ventral structures

87
Q

In decapentaplegic mutants dorsal parts of the embryo/larva are missing

A

TRUE

88
Q

In decapentaplegic mutants the first abdominal segment is enlarged

A

FALSE

89
Q

In decapentaplegic mutants denticle belts are dorsally expanded

A

TRUE

90
Q

In decapentaplegic mutants there are deletions between T1 and a5

A

FALSE

91
Q

In decapentaplegic mutants abdominal segments are fused

A

FALSE

92
Q

Twist mutant phenotype

A
  • ventral structures are missing = dorsalized
  • no extension and return of germ band
  • so grow and eggshell prevents extension = twisted

Cell Bio & Developmental Genetics (27 decks)

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