Genetic and Cellular Principles – Model organisms & General principles of
Development
Define the terms: determination, differentiation, and morphogenesis
Determination - The commitment of a cell to a particular path of differentiation, even though there
may be no morphological features that reveal this determination.
Differentiation - The normal process by which a less specialized cell develops or matures to become
more distinct in form and function
Morphogenesis - The development of form; the overall consequence
of determination, differentiation, and growth.
Understand that genes control the detailed process of development, but to do so they must
be responsive to signals from outside the cells
In the previous notes (Mammalian development)
Understand how model organisms such as the fruit fly Drosophila melanogaster have played
a critical role in our current understanding of the molecular principles of development
• The Homeotic genes specify regional identity to body segments. They define what structures
are produced by a particular segment.
• The Homeotic genes encode transcription factors.
• Homeotic genes all contain a conserved “Homeobox” DNA motif (Hox). A cluster of related
homeotic genes – the Hox gene cluster(s).
• Encodes a DNA binding domain in proteins.
• HOX genes encode transcription factors - regulate expression of other genes.
• Expression of HOX proteins is a Global Positioning System giving Regional Identity in animals.
Development
Define the terms: determination, differentiation, and morphogenesis
Determination - The commitment of a cell to a particular path of differentiation, even though there
may be no morphological features that reveal this determination.
Differentiation - The normal process by which a less specialized cell develops or matures to become
more distinct in form and function
Morphogenesis - The development of form; the overall consequence
of determination, differentiation, and growth.
Understand that genes control the detailed process of development, but to do so they must
be responsive to signals from outside the cells
In the previous notes (Mammalian development)
Understand how model organisms such as the fruit fly Drosophila melanogaster have played
a critical role in our current understanding of the molecular principles of development
• The Homeotic genes specify regional identity to body segments. They define what structures
are produced by a particular segment.
• The Homeotic genes encode transcription factors.
• Homeotic genes all contain a conserved “Homeobox” DNA motif (Hox). A cluster of related
homeotic genes – the Hox gene cluster(s).
• Encodes a DNA binding domain in proteins.
• HOX genes encode transcription factors - regulate expression of other genes.
• Expression of HOX proteins is a Global Positioning System giving Regional Identity in animals.
