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Explore the multiple mechanisms and interactions that regulate the timing, coordination, and differentiation of molecular, physiological, and behavioral events during organism development. Discover how gene expression, homeotic genes, apoptosis, and environmental stimuli shape the development process.
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Chapter 21 The Genetic Basis of Development Chapter 21 The Genetic Basis of Development
Organism Development • Multiple mechanisms regulate the timing and coordination of molecular, physiological and behavioral events that are necessary for the normal development of an organism.
Molecular • Cell differentiation results from the expression of genes for tissue-specific proteins. • Cell differentiation can also result from specific gene silencing. • Induction of transcription factors during development results in sequential gene expression.
Embryonic induction in development results in the correct timing of events • Cell division • Cell differentiation • Morphogenesis
Homeotic genes are involved in developmental patterns and sequences. ie. involved in determining where, when, and how body segments develop in flies. • Gene mutations in homeotic genes can result in abnormal development.
Apoptosis - Programmed cell death plays a role in normal development and differentiation. • Encoded for by a signal cascade of “suicide proteins”. • Essential to development in animals for normal nervous and immune systems. • Also important in limb development
Physiological • Events in organisms can involve interactions between environmental stimuli and internal molecular signals ie. Circadian rhythms, seasonal responses in animals and phototropism's in plants
Behavioral • Individuals can act on information and communicate to others. Responses to information are vital to natural selection. ie. Hibernation, migration and courtship rituals