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title: "Chapter\_3 Developmental Systems"

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# Chapter 3 Developmental Systems
##### P1 How does single cell with same genetic material turn into a multicellular organism?
##### P2 Development Stages
- **Ontogeny** - Entire development history from fertilized egg to adult
	- **Embryogenesis** - from fertilization to hatching of the egg
    - **Commitment** - staged process by which cell differences arise
        1. **Specification**
            - capable of autonomous differentiation in a neutral enviorment
            - location in embryo determines gene expression patterns, establishing certain cytoplasmic components and molecules that form gradients that establish cell identity and further development
            - not irreversibly determined, can still be transformed
        2. **Determination**
            - no longer reversible or transformable, even after transplantion
            - results in actual generation of morphological differences and specialized cell types
## Morphogens and Developmental Patterns
##### P1 Morphogen Gradients
- **Morphogens** - usually transcription factors
    - cells use conentration gradient to determine position in embryo
##### P2 Wolpert's 1960 'French Flag Model'
##### P3 Analogy to real organisms
- locally produced molecule produces gradient as it diffuses across cells
- indidivdual cells with receptors to the molecule use its concentration at their location in the gradient to respond proportionally
### Insect Eggs
##### P1 Chorion - insect eggshell
- keeps egg contents in, and environment out
- flexible enough to pass through ovipositor
- permit sperm for fertilization
- exachange oxygen and carbon dioxide
- allow escape of larva
- sometimes external structures for floating on water
- sometimes internal structures for respiration
##### P2 Balance between gaseous exchange and water loss
##### P3 Protection from evironmental assault
##### P4 Relative advancement of holometabolous eggs
#### Egg Membranes
##### P1 Chorion Synthesis
##### P2 Preparattion of follicle cells
##### P3 Vitreline and wax layer
##### P4 Endochorion and Exochorion
##### P5 Micropyle
##### P6 Respiratory appendages and operculum
##### P7 Temporal Expression profile of Genes coding for egg proteins
### Pattern Formation within the Oocyte
##### P1
##### P2
##### P3
##### P4
##### P5
##### P6
##### P7
##### P8
##### P9
### Hox Genes
##### P1
##### P2
##### P3
## Embryonic Development
##### P1
##### P2
### Blastoderm Formation
##### P1
##### P2
### Formation of the Germ Band
##### P1
##### P2
##### P3
##### P4
### Blastokinesis and Dorsal Closure
##### P1
### Formation of the Gut
##### P1
##### P2
### Formation of the Nervous System
##### P1
##### P2
### Formation of Eyes
##### P1
### Formation of Other Internal Organ Systems
##### P1
##### P2
##### P3
##### P4
### Eyespot Pattern Formation
##### P1
##### P2
##### P3
##### P4
##### P5
### Sex Determination
##### P1
##### P2
##### P3
##### P4
##### P5
##### P6
### Endocrinology of Embryonic Development
##### P1
##### P2
##### P3
##### P4
##### P5
##### P6
##### P7
##### P8