Hox genes
Segment identity regulators
Hox genes are regulatory genes that direct the formation of body segments and structures during embryonic development.
They act as master switches, telling cells their position and what body part to become.
The genes are arranged on chromosomes in the same order as the body parts they control—a phenomenon called colinearity: Hox genes explain why vertebrates share the same basic body organization. (Lowercase hox genes is an alternate form.)
Division into sections
- bilateral symmetryEqual halves along midline
- appendagesProjecting body parts
- thoraxCentral body cavity
- abdomenTorso's lower cavity
vertebrae · limbs · fins · wings · head · tail · dorsal · ventral
Formation of early life
- morphogenesisDevelopmental shape emergence
- cell fateCell's developmental outcome
- differentiationRecognizing meaningful differences
- organogenesisEmbryonic tissue becoming structures
Points sharing a line
- conservationPreventing waste or loss
- common ancestorOrigin point of descendants
- phylogenyEvolutionary relationships among organisms
- Cambrian explosionSudden appearance of complex life
segmentation
Division into sections
- bilateral symmetryEqual halves along midline
- appendagesProjecting body parts
- thoraxCentral body cavity
abdomen · vertebrae · limbs · fins · wings · head · tail · dorsal · ventral
embryogenesis
Formation of early life
- morphogenesisDevelopmental shape emergence
- cell fateCell's developmental outcome
- differentiationRecognizing meaningful differences
collinearity
Points sharing a line
- conservationPreventing waste or loss
- common ancestorOrigin point of descendants
- phylogenyEvolutionary relationships among organisms
Cambrian explosion · homology · co-option · macroevolution · diversification
enhancer
Agent of improvement
- developmental biologymorphogenesis, embryogenesis, gastrulation, organogenesis, ectoderm
- evo-devobody plan, serial homology, evolvability, modularity
- Conserved SequencesTATA box, histone, transfer RNA
- Developmental Genesdeformed, labial, caudal, nanos, wingless
- Drosophila geneticsMorgan, Muller, balancers, wingless, hedgehog
- gene familiesoncogenes