BIOA01H3 Chapter 20: Notes
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Chapter 20: Genes and Development
Gene expression in the development off organisms is hierarchical pattern. This means that one gene’s
activation triggers another’s in a chain reaction.
Regionalization and Specialization in Evo-Devo
Apart from genes only being hierarchical, they must also have the correct pattern and type of cells in
different parts of the embryo. There are 3 classes of genes that are responsible for pattern formation.
Segment Polarity genes
The Drosophila Fly
The embryonic development of the Drosophila fly is important for hierarchical control development.
Unlike mammals, the fly doesn’t have a zygote uses cell division. Instead, a concentration of nuclei
found in the center of the egg form a preliminary developmental structure (found in animals where it is
called a blastocyst) called a cellular blastoderm.
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