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Flashcards in Ch9 Deck (57)
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1

Superficial cleavage

cleavage confined to the cytoplasmic rim

2

Syncytial cytoplasm

all cleavage nuclei in a common cytoplasm

3

Energids

nuclei and their associated cytoplasmic islands

4

Nuclei move to the periphery in cycle

10

5

Membrane develops around nuclei in cycle

13

6

Cellular blastoderm

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

7

Blastoderm cellularization involves

furrow canals

8

Gastrulation

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

9

Distinguish the thoracic and abdominal regions by

differences in the cuticle

10

Anterior and posterior form from

the position of the egg in the ovary

11

Maternal effect genes

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

12

Bicoid and Hunchback

maternal effect genes that regulate the production of anterior structures

13

Nanos and Caudal

proteins that regulate the formation of posterior parts

14

Zygotic genes include

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

15

Gap genes

make broad, overlapping segments
• divide the embryo into broad regions with several parasegment primordia

16

Differing concentrations of gap genes cause trasncription of

pair-rule genes

17

Pair-rule genes

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

18

Pair-rule genes activate the transcription of

segment polarity genes

19

Segment polarity genes

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

20

Homeotic selector genes are regulated by

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

21

Homeotic selector genes

transcription determines the developmental fate of each segment

22

Axes patterned before

nuclei begin to function
(mRNA deposited)

23

Bicoid and hunchback are responsible for

head and thorax formation

24

Nanos and caudal are responsible for

abdomen formation

25

Tethered morphogens

bicoid and nanos

26

Hunchback and caudal are found

throughout the embryo

27

Fertilization leads to

translation of mRNAs to proteins

28

Bicoid is high in

the anterior region
• inhibits translation of caudal (in the anterior)

29

Nanos and pumilio bind

hunchback RNA
• no hunchback translation (in posterior)

30

Bicoid binds

hunchback enhancer
and stimulates transcription