2.9 - Specialization  experimentally, cells maintained in tissue culture will divide 50 times, regardless of when they are frozen and thawed  cell division in organisms is determined by specialization  dermal cells divide more than muscle, nerve, or secretory cells  spermatocytes and cancer cells divide continuously  specialized sperm stop dividing while cancer cells divide too rapidly to specialize and thus lose their normal functions the cell clock is turned on when differentiation (specialization) begins

SPECIALIZED CELLS 2.9 Many complex organisms, such as a human being or a maple tree, begin life as a single fertilized egg or a single cell. The cells in a complex organism are not all identical. They have been created to perform specific functions, such as digesting food, fighting disease, or coordinating the body’s movements. Specialized cells have physical and chemical differences that allow each type to perform one job very well. For example, the specialized cells in the photo help keep dirt out of the lungs. The orange goblet cells secrete mucus, while the hair-like extensions of the cells (called cilia) move the mucus along the trachea to remove inhaled dust and dirt.Specialized cells specialized cells

Specialized Cells Blood cellsmuscle cellsfat cellsnerve cells

Specialized Cells Root cellxylemchloroplastphloem

White Blood Cells

Sperm Cell

Skin Cells

Bone Cells