BIOLOGY Unit 4 Notes: Cell Division Basics & The Cell Cycle

(1) What is Cell Division? Processes cells use to make copies of themselves. Single Celled organisms can use it to reproduce. Types of Division: Mitosis Meiosis

(2) Why Do Cells Divide? Grow (make an organism larger and more complex) Repair (tissues that were damaged) Replace (lost / broken down cells) Reproduce (to make more cells or organisms)

(3) When do cells use Mitosis vs Meiosis? Make more NON-SEX CELLS (Somatic Cells). Make exact copies of cells. Maintains full set of genetic info in each new cell. Make more SEX CELLS (Gamete Cells). Increase genetic diversity in the organisms in a population. Cuts the amount of genetic info in ½.

(4) The Cell Cycle The cycle used to cells to prepare for cell division + divide: Makes copies of organelles. Doubles the size of the cell. Checks DNA for errors. Cells complete cell division after preparation.

(5) Cell Cycle Diagram Interphase: G1 S G2 G1 PHASE G1 CkPt M PHASE G2 S PHASE G2 PHASE

(6) Cell Cycle Stages G1 Phase = 1st Growth Phase Cell copies organelles and increases size. G1 Check Point Cell Makes sure cell is growing properly. S Phase = DNA Synthesis Phase Cell copies DNA G2 Phase = 2nd Growth Phase Cell continues to copy organelles and increase size. G2 Check Point Cell makes sure DNA was copied properly. M Phase = Mitosis or Meiosis Phase Cell actually divides.

(7) Cancer & The Cell Cycle If cells do not accurately check for errors during the G1 or G2 check points, defective or mutated cells will begin dividing in the organism. Cancer: Malfunctioning cells which divide and grow uncontrollably.