Coding 10 Flashcards

1
Q

What happens to the energids in a syncitial drosophila embryo?

A

The nuclei and the energids migrate to the periphery and use ingression to make the syncitial blastoderm

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1
Q

What is an energid?

A

The cytoplasmic space that the nuclei in a syncitial blastoderm interact with

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2
Q

What do the pole cells form?

A

The posterior and the germ cell precursors

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3
Q

Relative to nuclear division when can cleavage occur?

A

When there are the right number of nuclei to form the syncitium

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4
Q

What is superficial cleavage?

A

When the yolk limits the cleavage of the embryo to the rim of the egg

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5
Q

What is a syncitial blastoderm?

A

A blastoderm is an embryo that has undergone cleavage and has a cavity and in this case the only membrane is the one surrounding the egg

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6
Q

What is the cellular blastoderm?

A

When the cell membranes fold inward between the nuclei and divide into individual cells

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7
Q

What are the maternal affect genes?

A

These are the genes that are needed for early embryonic development

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8
Q

What is the mid-blastula transition?

A

When the maternal mRNA are degraded the gap stages are added and the synchonicity of the cell division is lost

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9
Q

When do zygotes produce their own genes?

A

Cycle 11

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10
Q

When does zygote transcription get enhanced?

A

Cycle 14

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11
Q

How does the ventral tube form?

A

when the ventral midline folds inwards and then the ventral furrow forms which then pinches into the tube (analogous to the neural tube forming)

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12
Q

How does the germ band for?

A

When the cells converge at the ventral midline to form the embyo’s trunk

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13
Q

How do germ line cells form?

A

An oogonium generates an oocyte which divides and gives rise to 16 cells

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14
Q

What do germ line cells do?

A

They activate nurse cells

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15
Q

What do nurse cells do?

A

They make proteins and mRNA which are then transported into the oocyte

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16
Q

When are zygotic genes activated? (Before Vs. After)

A

After fertilization

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17
Q

What are gap genes?

A

Encodes for transcription factor that divides the embryo into 3 segments

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18
Q

What are pair-rule genes?

A

Divides the embryo into 7 segments and it is regulated by various gap gene products

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19
Q

What are segment polarity genes?

A

Transcription factors from pair-rule genes activate these genes to make 14 segments

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20
Q

How are bicoid and nanos tethered to the anterior or posterior?

A

By the 3’UTR to the unfertilized egg

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21
Q

When are bicoid and nanos translated?

A

After ovulation and fertilization

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22
Q

Since there is no cell membrane in a syncitial blastoderm what happens?

A

Polarity is established

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23
Q

What is the role of the nurse cells in relation to other genes?

A

It produces transcription factors that are used to regulate the expression of hunchback and caudal

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24
Q

How does bicoid repress caudal?

A

Bicoid proteins bind to the 3’UTR of the caudal and prevent the addition of the 5’ Cap which prevents caudal to be translated

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25
Q

Why does bicoid repress caudal?

A

If both are expressed the head and the thorax fail to synthesize proper regions in the anterior

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26
Q

How does nanos repress hunchback?

A

The nanos proteins bind to the 3’UTR of the hunchback mRNA and prevent the addition of the 5’Cap

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27
Q

What is bicoid?

A

A gene responsible for making the head in the anterior of the fly

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28
Q

What is nanos?

A

A gene responsible for making the tail in the posterior of the fly

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29
Q

What is caudal?

A

It activates genes responsible for making the hindgut

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30
Q

How is bicoid related to hunchback?

A

It upregulates and activates it

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31
Q

What impact drosophila cell fate?

A

Protein gradients and signals from other cells

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32
Q

What is the effect of gap mutants?

A

Lack large regions of the body

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33
Q

What is the effect of pair rule mutatations?

A

Lacks every other segment

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34
Q

What is the effect of segment polarity mutations?

A

Defects in every segment

35
Q

Do the mutations impact the segment?

A

No, it impacts the sub-segments or the parasegments which are also divided into anterior and posterior

36
Q

What happens if kruppel expression is absent?

A

The parasegments are lost

37
Q

What happens after the inital gap genes are expressed from the MEGs?

A

They are stabalized by the gene products from one another

38
Q

What cycle are pair-rule genes activated?

A

Cycle 13

39
Q

What proteins do segment polarity genes encode for?

A

Wnt and Hit

40
Q

What is the function of engrailed?

A

Engrailed activates hedghog

41
Q

When is engrailed activated?

A

When there are high levels of even-skipped genes such as fushi tarazu or paired

42
Q

When is engrailed repressed?

A

When there are high levels of odd-skipped genes

43
Q

Where is engrailed activated?

A

In the anterior of the parasegment and posterior of the segment

44
Q

Where is wingless transcribed?

A

Anterior to where engrailed is transcribed

45
Q

What is wingless?

A

A type of Wnt protein

46
Q

Since RNA and proteins are short lived how can the cell regulate this?

A

By nearby cells producing wingless to regulate hedgehog

47
Q

What are homeotic selector genes?

A

These genes specify the characteristics and structures for each segment

48
Q

What leads to specification in flies?

A

Signalling cascades from the MEG

49
Q

When does the Gurken gene lead to ventral-dorsal axis formation?

A

When the nucleus is pushed into the corner of the oocyte

50
Q

What is the dorsal protein?

A

It is a transcription factor that is also a morphogen and generates the ventrum

51
Q

What produces the dorsal protein?

A

MEG

52
Q

Is the dorsal protein in the energrid?

A

So long as it is bound to the protein, cactus

53
Q

What happens when gurken inhibits pipe in the dorsal follicle?

A

Pipe is expressed in the ventral follicle which leads to cactus phosphorylation which detatches from the dorsal protein and allows it to translocate into the nucleus

54
Q

What does pipe produce?

A

The mesoderm

55
Q

What is the homolog for dorsal?

A

NF-kb transcription factor

56
Q

What is the homolog for toll?

A

Toll-like receptor

57
Q

What is the homolog for gurken?

A

Epidermal growth factor ligand (RTK ligand)

58
Q

What is the homolog for torpedo?

A

Epidermal growth factor receptor (RTK ligand)

59
Q

What is the homolog for SOG?

A

Chordin (BMP inhibitor)

60
Q

What is the homolog for DPP?

A

BMP

61
Q

What is the homolog for MAD?

A

SMADs 1/5

62
Q

What is gurken?

A

MEG

63
Q

When is dorsal mRNA translated?

A

After fertilization it is a MEG

64
Q

What is the effect of segment polarity genes, HH, ultrabithorax, and antennapedia on the dorsal release?

A

No effect you would get the wild type because these genes are expressed after cycle 14 for cellularization

65
Q

What happens at cycle 10-12?

A

Syncitial blastoderm

66
Q

What happens at cycle 13?

A

MBT

67
Q

What happens at cycle 14?

A

Cellularization

68
Q

What gene is activated at cycle 10?

A

Gap genes

69
Q

What gene is activated at cycle 13?

A

Pair rule genes

70
Q

What gene is activated at cycle 14?

A

Segment polarity genes

71
Q

In a wild type what does the dorsal gradient look like?

A

High translocation to the nuclei in the ventral side and nothing in the dorsal

72
Q

What causes all the nuclei to have translocated dorsal proteins?

A

The absence of cactus

73
Q

What protein causes none of the nuclei to have translocated dorsal proteins?

A

The removal of pelle

74
Q

What is twist?

A

This gene’s expression leads to gastrulation and the formation of the mesoderm by the invagination at the ventral furrow

75
Q

What activates twist?

A

Dorsal proteins

76
Q

What is the process of the ventral-dorsal polarity in drosophila?

A
  1. The oocyte nucleus moves to the dorsal side of the oocyte
  2. After fertilization gurken is translated and the torpedo receptor receives the signal at the dorsal end
  3. The torpedo signals the follicle cells to form the dorsal morphology (not in the embryo)
  4. The pipe synthesis is inhibited in the dorsal follicle cells
  5. Gurken does not diffuse to the ventral side because of the distance
  6. The ventral follicle cells produce pipe
  7. Pipe sulfates the ventral vitelline membrane
  8. A protease called the gastrulation defective binds to the sulfated vitelline membrane
  9. GD cleaves the snake protease and activates it
  10. Snake cleaves the easter protease
  11. Easter binds to the spatcle protein
  12. Spatzle binds to the toll receptor as a ligand
  13. Spatzle activates pelle in the embryo
  14. Pelle phosphorylates cactus and releases it from dorsal
  15. Dorsal is then translocated into the nucleus and acts as a transcription factor
77
Q

If the process of the ventral-dorsal polarity is in the embryo only at the spatzle phase where were the processes happening before that?

A

The paravitelline membrane

78
Q

What is a zymogen?

A

When a protein is cleaved it is activated

79
Q

Where is the DPP the highest?

A

Dorsal

80
Q

Where is MAD the highest?

A

Dorsal

81
Q

Where is dorsal the highest?

A

Ventral

82
Q

What does inhibiting DPP/BMP do?

A

Leads to the induction of the nervous system

83
Q

What is tolloid?

A

A protease that removes SOG

84
Q
A