Genes and body plans

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  • Created by: Steff06
  • Created on: 17-06-16 18:28
What happens when Drosophila eggs are laid?
A series of mitotic divisions are triggered.
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What happens at first?
No new cell membranes form and a multinucleate syncytium is formed.
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What happens after the 8th division?
The 256 nuclei migrate to the outer part and by the 11th division, the nuclei form an outer layer around a central, yolk-filled core.
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What happens to the division rate?
Division rate slows and nuclear genes switch from replicating to transcribing.
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What does the plasma membrane do?
Folds inwards around the nuclei and the resulting cells form a single outer layer.
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Describe the division of the embryo
Embryo divides into a series of segments which correspond to the organism's organisation.
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How is the head formed and how many segments are there?
3 segments merge to produce the head. There are 3 thoracic segments and 8 abdominal segments.
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When do the legs, wings and antennae develop?
When the larval form becomes an adult.
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What is the development genetically mediated by?
Homeobox genes.
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What can some genes also determine?
The embryo's polarity.
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What do homeotic selector genes specify?
Specify the identity of each segment and direct the development of individual body segments.
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What are the 2 gene families?
Complex that regulates development of thorax and abdomen segments and the complex that regulates development of head and thorax segments.
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What is antennapedia?
A condition where the antennae look more like legs.
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What do the homeobox genes each contain?
Contain a sequence of 180 base pairs and this sequence produces polypeptides of 60 amino acids.
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What are some of these polypeptides?
Transcription factors that bind to genes upstream and initiate transcription.
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What are the clusters called that Homeobox genes are arranged in?
Hox clusters.
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How many clusters do Drosophila and vertebrates have?
Drosophila have 2 clusters and vertebrates have 4 clusters.
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How are the homeobox genes expressed?
Expressed in specific patterns in certain stages during the development of the embryo.
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Other cards in this set

Card 2

Front

What happens at first?

Back

No new cell membranes form and a multinucleate syncytium is formed.

Card 3

Front

What happens after the 8th division?

Back

Preview of the front of card 3

Card 4

Front

What happens to the division rate?

Back

Preview of the front of card 4

Card 5

Front

What does the plasma membrane do?

Back

Preview of the front of card 5
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