Cell Cycle

• Levels of Organization

  1. Atom
  2. Molecule
  3. Macromolecule
  4. Organelle
  5. Cell
  6. Tissue
  7. Organ
  8. Organ systems
  9. Organism
  10. Population
  11. Community
  12. Ecosystem
  13. Biosphere
• A cell is the smallest unit that is capable of performing life functions. They are the building blocks of life, and can either be unicellular or multicellular
• The human body is made up of 37.2 trillion cells.
• Zacharias Janssen invented the microscope in 1590.
• Robert Hooke discovered the cell in 1665. He used the light microscope to observe cork cells.
• Matthias Schleiden and Theodore Schwann proposed the first two postulates of the cell theory in 1838.
• Robert Remak discovered the third postulate of the cell theory.
• The Cell Theory

  1. All organisms are made up of one or more cells.
  2. Cells are the basic units of life.
  3. All living cells come from other living cells.
• Cell Division - The process by which a cell divides to produce two identical daughter cells.
• Prokaryotes (bacteria)

  Binary Fission - divides forming two new identical cells
• Eukaryotes

  Mitosis - Cell or organism growth, replacement or repair of damaged cells
• Meiosis - formation of sex cells, or gametes
• Why do cells divide?

  • DNA overload
  • Exchange of materials (food and oxygen have to cross membrane very quickly and waste must get out)
  • Growth and development
  • Cell replacement
  • Asexual Reproduction
• Chromatids - the duplicated chromosome attached at the point of the centromere.
• Chromatin - uncoiled DNA wrapped around histones to form chromatin fibers
• Chromosome - A long, coiled DNA molecule that carries genetic information