1. Developmental Biology
Embryology is the comparative study of the development of different organisms
Gene expression is
Temporal - genes expressed in relation to time
Spatial - genes expressed in relation to place in organism

2. Gene Regulation in Bacteria
Bacteria adapt to changes in their surroundings by using regulatory proteins to turn groups of genes on and off in response to various environmental signals
The DNA of Escherichia coli is sufficient to encode about 4000 proteins, but only a fraction of these are made at any one time. E. coli regulates the expression of many of its genes according to the food sources that are available to it.

3. The lac operon
The best understood cell system for explaining control through genetic induction is the lac operon
Jacob & Monod (1961) - regulation of lactose
metabolism in E.coli
Composed of 3 segments (GENES), or loci of DNA:
The REGULATOR - composed of gene that codes for a repressor protein which can repress the operon.
The OPERATOR - can start transcription of the structural genes
The STRUCTURAL - contains structural genes encoding the enzyme b-galactosidase

4. Embryonic development

5. Differentiation of cells into tissues and organs
Fertilisation produces zygote
Zygote divides by mitosis to produce ball of cells
(blastula – stem cells)
Ball of cells undergoes changes to give form to the developing organism with tissues and organs
Cells become specialised and differentiated
Controlled by genes being 'on' or 'off'

6. Neuralation - neural tissues form including brain and spinal cord
Cell migration - cells move to specific sites for tissue development
Organogenesis - basic body form completed, tissues and organs develop.
Growth - embryo grows
Future - birth and growth to maturity
Dynamic and interactive process between cells

8. Vertebrate embryonic development
Cleavage - zygote divides giving blastomere
Blastula - hollow ball of cells
Gastrulation - ball of cells folds in on itself, germ layers formed, symmetry fixed
Ectoderm - skin, epidermis(nails, skin glands), sense receptors, cornea/lens, nervous system, etc.
Endoderm - lining of digestive tract and respiratory system, liver, pancreas, thyroid, thymus, etc.
Mesoderm - spinal cord, skeleton, muscles, circulatory/excretory/reproductive systems, lining of body cavity.

9. Fruit Flies (Drosophila melanogaster)

10. Maternal effect genes
Gap genes
Pair rule genes
Segmentation
genes

11. Fruit fly head development