• Stem Cells: unspecialized cells during early stage of embryonic development that can reproduce indefinitely and differentiate (become any) into specialized cells
    • But as development continues → cells differentiate & become specialized → cell divisions make more specialized cells
    • Cells become specialized because transcription factors activate some genes while suppressing others               
      • Process is self-reinforcing as the cell can signal to itself
      • Genes permanently turned off associated with DNA methylation and histone modification
    • Embryonic stem cells (ES): Can become any kind of cell (including sperm and egg)
    • Adult body stem cells: can only replace non-reproducing specialized cells (not sperm and egg)
    • Pluripotent: can become any type of cell
    • Totipotent: cells that can form new fetus
    • Unipotent: a cell that has differentiated and cannot become any type of new cell
    • Differential Gene Expression: expression of different genes by cells with the same genome

Morphogenesis, Pattern Formation, and Axis Development

  • Pattern Formation: the process of organizing tissues and organs that begins in early embryo
    • Various genes code for pattern formation of organisms
  • Positional Information: molecular cues that control pattern formation, tells a cell its location relative to the body’s axes and to other cells
  • Maternal effect: offsprings axes encoded by mother’s genes (ie. Cytoplasmic determinants),

So mutations passed to all