Introduction to Animal Development Flashcards

1
Q

What is an animal model?

A

Any species that has been widely studied.

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2
Q

What are important features of animal models?

A

They are easy to maintain, breed, have a known genome sequence, have experimental advantages and a low cost.

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3
Q

What are important features of genetic models?

A

A large array of mutants available, a large number of offspring and a short generation time/gestation time.

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4
Q

What are important features of embryological models?

A

Robust embryos that can be easily manipulated, a large number of embryos and exhibit external development.

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5
Q

What are important features of genomic models?

A

Having relevance to the human genome, being good disease models and be able to used for drug testing.

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6
Q

What are common developmental models for invertebrates?

A

Nematode (worm - caenorhabitis elegans) and the drosophila melangaster - fruit fly.

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7
Q

What are the main advantages of the models used for invertebrates?

A

The worm has very few cells and the drosophila has lots of mutants.

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8
Q

What are common developmental models for vertebrates?

A

The zebrafish (danio rerio), the African clawed frog (xenopus laevis) the chicken (gallus gallus domesticus) and the mouse (mus musculus).

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9
Q

Why are these models for vertebrates useful?

A

The zebrafish and african frog have external development, fish has clear embryo for imaging, frog and chicken are good for experimental embryology and mouse is good for genetic modification.

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10
Q

How do xenopus (frog) eggs/embryos differ from mammals?

A

They have a dark pigmented animal pole and a egg-rich vegetal pole.

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11
Q

How does the rate of division for the blastomeres (cells of animal pole) vary compared to the yolk cells (cells of the vegetal pole)?

A

The blastomeres divide more rapidly and therefore become more numerous.

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12
Q

What is a key point about the blastula stage embryo?

A

It has not yet changed in size.

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13
Q

What happens when sperm enters the animal pole?

A

Rotation of the cortical cytoplasm to reveal a grey crescent region opposite the sperm entry point.

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14
Q

Where is the dorsal lip?

A

Just below the grey crescent region. It forms on the opposite side of where the sperm enters the animal pole.

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15
Q

When is the dorsal lip specified?

A

Right at the beginning of fertilisation. It is an important region.

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16
Q

What happens in gastrulation?

A

Cells move into the embryo and generate the 3 germ layers.

17
Q

What are the three germ layers?

A

The ectoderm, mesoderm and endoderm.

18
Q

What happens after the three layers are generated?

A

The animal pole cells at the dorsal lip of the blastopore begin to involute causing the future mesodermal and endodermal cells to be moved interiorly.

19
Q

What is formed and displaces the blastocoel?

A

The archenteron (primitive gut).

20
Q

Where will the head end (anterior end) be formed?

A

At the leading edge of the mesoderm.

21
Q

How is a neural tube formed?

A

Neural folds appear either side of a neural groove and they move together to form a closed neural tube.

22
Q

Define blastula stage.

A

A ball of cells.

23
Q

Define gastrulation.

A

Cell movements that produce germ layers.

24
Q

What is the neural plate stage?

A

The embrro after gastrulation.

25
Q

What is neurulation?

A

Cell movements which roll up the neural tube.

26
Q

What does dorsal mean?

A

Back.

27
Q

What does ventral mean?

A

Belly.

28
Q

What is the basic process for animal cloning?

A

An unfertilized egg is radiated with UV to remove the nucleus and a nucleus from a blastula is injected into the egg.

29
Q

How was it found that the frog produced was a clone of the nucleus that was injected?

A

An albino frog nucleus was taken and an albino frog was formed.

30
Q

How can a similar method be used to clone the frog from differentiated adult cells?

A

Adult skin cells can be cultured a nucleus can be removed. The nucleus can be inserted into a UV radiated egg and a tadpole will develop.

31
Q

How does the cortex differ from the rest of the cells in the fertilised egg?

A

It contains other important factors that make it special.

32
Q

When the sperm enters the cell, where is the movement of the cytoplasm?

A

The cytoplasm within the cortex only.

33
Q

What is the significance of the movement of the cytoplasm and the formation of the grey crescent area?

A

It means that key factors will be moved to another area that will trigger gastrulation.

34
Q

Define cell fate.

A

Depending on where a cell is in an embryo it is going to become a certain type of cell in the future.