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Zoology > Principles of Development ch 8 > Flashcards

Principles of Development ch 8 Flashcards

1
Q

What are the stages in animal developement?

A

1.Gamete formation
2. Fertilization
3. cleavage
4. gastrulation
5. Organogenesis
6. growth

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2
Q

Gamete formation

A

Sperm and eggs form, mature

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3
Q

Fertilization

A

the union of male and female gametes to form a zygote

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4
Q

Cleavage

A

a series of mitotic divisions whereby the enormous volume of egg cytoplasm is divided into numerous smaller, nucleated cells.

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5
Q

Gastrulation

A

-converts the spherical blastula into a two- or three- layered embryo
-Germ layers form
establish body plan

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6
Q

What is a hollow ball of cells called?

A

blastula

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7
Q

Cleavage subdivides the mass of the zygote until a cluster of cells called a __________

A

Blastula

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8
Q

Prior to fertilization egg accumulates yolk & contain ________ ____________such as transcription factors and inducing factors, that switch genes on or off following fertilization.

A

Morphogenetic
Determinants

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9
Q

Entrance of more than one sperm, called ________, must be prevented because union of more than two haploid nuclei would be ruinous for normal development. Entrance of more than one sperm produces a polyploid egg nucleus, which cannot undergo normal division: more than two mitotic spindles form, so chromosomes are unevenly di- vided among daughter cells.

A

polyspermy

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10
Q

Fast block

A
  • change membrane potential-contact of the first sperm with the egg membrane is instantly followed by an electrical potential change in the egg membrane that acts as a transient electrical barrier to pre- vent additional sperm from fusing with the membrane
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11
Q

what comes first, fast block or slow block?

A

fast block

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12
Q

slow block

A
  • cortical reaction; form fertilization membrane
    -a cortical reaction in which thousands of enzyme-rich cortical granules located just beneath the egg membrane fuse with the membrane and release their contents into the space between the egg membrane and the overlying vitelline envelope
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13
Q

zygote

A
  • fused egg + sperm
    -fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm)
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14
Q

cleavage

A

a series of mitotic divisions whereby the enormous volume of egg cytoplasm is divided into numerous smaller, nucleated cells.

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15
Q

Single cell (zygote) divides into many cells (blastomeres)

A

cleavage

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16
Q

Blastula

A

hollow ball of cells

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17
Q

Blastocoel

A

fluid filled space in center of a blastula

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18
Q

is a blastula a single cell?

A

no it is many cells

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19
Q

cleavage planes
at 90°; blastomeres lie atop each other

A

radial cleavage

20
Q

cleavage planes
at 45° angle; blastomeres lie in
cleavage furrows

A

Spiral Cleavage

21
Q

divide completely
through the egg

A

Holoblastic cleavage

22
Q

When little yolk is present, cleavage furrows extend completely through the egg in _________ _________

A

holoblastic cleavage

23
Q

the cleavage furrow does not completely divide the cytoplasm of the egg at each cell division. When much yolk is present, cleavage is__________ , with cells sitting atop a mass of undivided yolk

A

meroblastic

24
Q

____________ converts the spherical blastula into a two- or three- layered embryo.

A

Gastrulation

25
Q

Archenteron

A

primitive gut
-the cavity within an embryo at the gastrula stage of development that eventually becomes the digestive cavity.

26
Q

Blastopore

A

opening for gut

27
Q

Diploblastic

A

2 tissue layers
ectoderm and endoderm

28
Q

ectoderm

A

outer layer

29
Q

endoderm

A

inner layer, lines gut

30
Q

what is a blastopore mouth called?

A

Protostome

31
Q

what is a blastopore anus called?

A

Deuterostome

32
Q

Triploblastic

A

3 tissue layers
ectoderm, mesoderm, and endoderm

33
Q

Acoelomate

A

no body cavity; mesoderm fills
blastocoel

34
Q

Animals without a coelom are called what?

A

acoelomate

35
Q

Pseudocoelomate

A

mesoderm partially fills
blastocoel; lines ectoderm
-organisms that have false body cavities

36
Q

Coelomate

A

body cavity is
completely surrounded by
mesoderm

37
Q

After Coelom Formation:

A

 3 tissue layers: ectoderm, mesoderm, endoderm
 2 body cavities: gut cavity & fluid filled coelom (body cavity)

38
Q

Cytoplasmic Specification

A

The cytoplasm of a fertilized egg is not homogeneous. It contains unequally distributed morphogenetic components such as mRNAs and proteins, which act as enzymes or as transcription factors. These components may be tethered to the cytoskeleton. As cleavage pro- ceeds, the mRNAs and proteins are unequally partitioned among the resulting new cells (blastomeres). Thus, the fate of each cell is spec- ified by the type of cytoplasm it acquires in cleavage, and even iso- lated cells differentiate along the path dictated by the cytoplasmic components. Cytoplasmic specification, sometimes called autono- mous specification, causes mosaic development of the embryo. The term “mosaic” is used because the embryo appears to be a composite of independently developing parts rather than of interacting parts

39
Q

Conditional Specification (Induction)

A

What a cell becomes depends upon its position in the embryo. Its fate is determined by interactions with neighboring cells.

40
Q

_______________ _____________ leads to regulative development; early blastomeres can be separated and form a complete individual

A

Conditional specification

41
Q

How is cytoplasmic specification different from induction?

A

-cytoplasmic specification
Each cell with different instructions, Most Protostomes
-induction
Early blastomeres not fated
Deuterostomes

42
Q

Protostome vs. Deuterostome Development

A

Protostome:
spiral cleavage, mosaic, blastopore=mouth, Enterocoelous
Deuterostome:
radial cleavage, regulative, blastopore= anus,
Schizocoelous

43
Q

8.9 Name the derivatives of ectoderm, endoderm, and mesoderm.

A

Ectoderm: Skin, hair, nails, Nervous system
Mesoderm: Circ. System, Line body coelom, Somites (bone & muscle)
Endoderm: Respiratory tract, Gut tube, Liver, pancreas

44
Q

How do cells get committed to their fate?

A

– Cytoplasmic Specification
– Conditional Specification (Induction)

45
Q

8.7 What is the importance of homeotic genes in animal development?

A

specifying cell identity and positioning during embryonic development

Zoology (23 decks)

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