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Cell Bio & Developmental Genetics > Ch9 > Flashcards

Ch9 Flashcards

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Biology 101 flashcards
1
Q

Superficial cleavage

A

cleavage confined to the cytoplasmic rim

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2
Q

Syncytial cytoplasm

A

all cleavage nuclei in a common cytoplasm

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3
Q

Energids

A

nuclei and their associated cytoplasmic islands

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4
Q

Nuclei move to the periphery in cycle

A

10

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5
Q

Membrane develops around nuclei in cycle

A

13

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6
Q

Cellular blastoderm

A

cells (nuclei + membrane) in a single layer around yolk core (around perimeter)

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7
Q

Blastoderm cellularization involves

A

furrow canals

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8
Q

Gastrulation

A
  1. segregation of the mesoderm, ectoderm, and endoderm
  2. mesoderm (at ventral midline) makes a ventral furrow - layer of mesoderm tissue beneath ventral ectoderm
  3. endoderm invaginates - 2 pockets and anterior and posterior of the ends of the ventral furrow (pole cells to posterior pocket)
  4. embryo bends –> cephalic furrow
  5. ectoderm on surface and and mesoderm converge and extend, migrate to ventral midline to make the germ band
  6. germ band extends posterioroly to the top (dorsal)
  7. the nervous system forms from 2 regions of ventral ectoderm
  8. specification of cell types along anteriorposterior and dorsal-ventral by interaction of cytoplasmic materials
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9
Q

Distinguish the thoracic and abdominal regions by

A

differences in the cuticle

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10
Q

Anterior and posterior form from

A

the position of the egg in the ovary

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11
Q

Maternal effect genes

A

encode translational/transcriptional proteins that activate/repress the expression of zygotic genes

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12
Q

Bicoid and Hunchback

A

maternal effect genes that regulate the production of anterior structures

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13
Q

Nanos and Caudal

A

proteins that regulate the formation of posterior parts

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14
Q

Zygotic genes include

A

gap, pair-rule, polarity, and homeotic sector genes

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15
Q

Gap genes

A

make broad, overlapping segments

• divide the embryo into broad regions with several parasegment primordia

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16
Q

Differing concentrations of gap genes cause trasncription of

A

pair-rule genes

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17
Q

Pair-rule genes

A
  • transcribed due to concentrations of gap genes
  • divide the embryo into periodic units (7 vertical bands)
  • subdivide the broad gap gene regions into parasegments
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18
Q

Pair-rule genes activate the transcription of

A

segment polarity genes

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19
Q

Segment polarity genes

A

mRNA and protein divide the embryo into 14 units, establishing periodicity
• responsible for maintaining certain repeated structures within each segment

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20
Q

Homeotic selector genes are regulated by

A

the products of
• gap genes
• pair-rule genes
• segment polarity genes

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21
Q

Homeotic selector genes

A

transcription determines the developmental fate of each segment

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22
Q

Axes patterned before

A

nuclei begin to function

mRNA deposited

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23
Q

Bicoid and hunchback are responsible for

A

head and thorax formation

24
Q

Nanos and caudal are responsible for

A

abdomen formation

25
Q

Tethered morphogens

A

bicoid and nanos

26
Q

Hunchback and caudal are found

A

throughout the embryo

27
Q

Fertilization leads to

A

translation of mRNAs to proteins

28
Q

Bicoid is high in

A

the anterior region

• inhibits translation of caudal (in the anterior)

29
Q

Nanos and pumilio bind

A

hunchback RNA

• no hunchback translation (in posterior)

30
Q

Bicoid binds

A

hunchback enhancer

and stimulates transcription

31
Q

The Bicoid, Hunchback, and Caudal proteins are

A

transcription factors whose concentration activates/represses zygotic genes (transcription)

32
Q

Anterior organizing center

A

Bicoid

33
Q

2 genes keep Bicoid

A

at anterior
• exuperantia and swallow
• absence = bicoid diffuses, less steep gradient, poorly formed head with extended mouth region

34
Q

Bicoid represses

A

translation of caudal RNA

35
Q

Bicoid is a

A

transcription factor that activates hunchback

36
Q

Genes for head formation need

A
  • Bicoid for activation

* Hunchback for transcription

37
Q

Nanos inhibits

A

hunchback transcription in the posterior
• hunchback bound by Pimilio
• Pumilion joined by Nanos
–> no hunchback translation in posterior

38
Q

Anterior and posterior termini

A 
anterior = acron
posterior = telson
39
Q

Torso gene

A

terminal gene
• activated in the ends
• found throughout

40
Q

Mutation in the torso gene leads to

A

no acron or telson

41
Q

The torso gene is activated by the

A

Torso-like protein
• activates production of kinases that inactivate the transcriptional inhibitor of tailless and huckebin gap genes that specify the termini

42
Q

Terminal genes alone

A

both terminal regions telsons

• bicoid also present = 1 acron

43
Q

The anterior-posterior axis involves 3 sets of genes

A
  • the anterior organizing center
  • the posterior organizing center
  • the terminal boundary region
44
Q

Cell fate commitment has 2 steps

A
  1. specification

2. determination

45
Q

Specification

A

a loose commitment

• flexible (can receive signals from environment eg morphogens)

46
Q

Determination

A

irreversible

47
Q

The transition from specification to determination is mediated by

A

segmentation genes

48
Q

Segmentation genes

A

genes that divide the early embryo into a repeating series of segmental primordia

49
Q

Mutations of segmentation genes often affect

A

parasegments

50
Q

Parasegments

A

regions of the embryo separated by mesodermal thickenings and ectodermal grooves
• 14 in total

51
Q

A parasegment consists of

A
  • the posterior of the anterior segment

* the anterior of the segment behind

52
Q

The transition from an embryo with gradients of morphogens into an embryo with distinct units is mediated by

A

gap genes

53
Q

Pair-rule genes are activated by

A

the products of gap genes interacting with products of neighboring gap genes

54
Q

Mutations of segment polarity genes leads to

A

a portion of each segment is deleted and replaced with a mirror image of another portion

55
Q

Segmentation genes are

A

transcription factors that use the gradients of the early cleavage embryo to transform the embryo into a periodic, parasegmental structure

56
Q

Homeotic selector genes are regulated by

A

gap and pair-rule genes

57
Q

Homeotic selector genes

A

determine the identity of each segment

Cell Bio & Developmental Genetics (27 decks)

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