Cell Cycle

Cell Cycle

• The Cell goes through a cycle
• Most of the time the cell is in interphase which is where the cell does its work
• Specific interphase is dependent on cell type (ie Liver or Nerve, etc)
• During interphase the cell also prepares for cellular division by DNA duplication
• Cellular division occurs after DNA replication, afterward the cell cycle repeats
• A cell can only divide so many times, this is determined by the cellular clock
• The more specialized the cell, the less it divides. For example, nerve cells, muscle cells and secretory cells do not divide as much as skin cells and cells from the digestive tract.
• Cells that divide continuously include spermatocytes (one billion a day!!!!) and cancer cells

Cell Specialization

• After fertilization cells begin to rapidly divide and eventually differentiate into specialized cells.
• Every cell contains the same genetic material
• In specialized cells certain genes are activated, while others are inactivated.
• Gene expression determines cell type
• Once cells become specialized they can only produce more specialized cells (liver cells can only make other liver cells)
• Cells that are not specialized and that make all types of cells are called TOTIPOTENT
• an example of these cells are STEM CELLS