Mitosis & Meiosis

How cell division works


  • The series of event that cells go through as they grow/divide
  • Process:
  1. Grows (Interphase/G1/S/G2)
  2. Prepares for division (Mitosis/Prophase/Metaphase/Anaphase/Telophase)
  3. Cytoplasm divides to form two daughter cells
  • Interphase
  1. Longest phase
  2. Cell appears to be at rest
  • G1 phase
  1. Period where cells do most of growing
  • S phase
  1. DNA is copied
  • G2 phase
  1. Shortest phase
  2. Organelles needed for cell division are produced
  • At the end of this phase cell gets ready to divide/start M phase
  • M phase
  1. Mitosis (preparation) and cytokinesis (cell division)
  2. Cell division has two stages in eukaryotes
  • Stage 1: Mitosis
  • Prophase
  1. Nuclear membrane breaks down
  2. Nucleolus disappears
  3. Chromatin condenses into chromosones
  4. Centrioles separate and a spindle begins to form
  • Metaphase
  1. Chromosomes line up across the middle
  2. Each chromosome connects to a spindle fiber at its centromere
  • Anaphase
  1. Sister chromatids separate into individual chromosomes and move to opposite ends
  • Telophase
  1. Nucleolus reappears
  2. Chromosomes gather at the opposite ends
  3. They lose their shape
  4. New nuclear envelopes begin to form
  • Stage 2: Cytokinesis
  1. Cytoplasm pinched in half
  2. Each daughter now has all chromosomes (diploid-2n cells)


Onion Cell Mitosis