- Domains and Kingdoms Three Domains of Life In the three-domain system of classifications, all known organisms belong to one of three domains–Bacteria, Archaea, or Eukarya.

Life Comes From Life Francesco Redi designed one of the first controlled experiments. In his experiment, Redi showed that flies do not spontaneously arise from decaying meat. -

Life Comes From Life Louis Pasteur’s carefully controlled experiment demonstrated that bacteria arise only from existing bacteria. - What Is Life?

What do all living things have in Common?

All living things are made of cells Unicellular- one cell Multicellular- many celled Eukaryotic- has a nucleus Prokaryotic- no nucleus

All living things are organized. From as small as a molecule to as large as an organism. – atom, compound, cell, tissue, organ, organ system, organism Organization depends on their function

All living things use energy? Metabolism----the chemical reactions of all the energy intake and use People take chemical energy (food) and change it in heat and mechanical energy Plants take light energy(sun) and change it into chemical energy(food)

All living things maintain a stable internal environment Homeostasis Examples: – Sweating – Shivering – goosebumps

All living thing grow and develop Growing is getting more and more cells in body – As you get bigger you have more cells Development is when the cells become specialized and have a particular job or function….example of blood cells All is determined by the genetic code for life

All living things reproduce Sexual reproduction- require two cells and creates a unique offspring Asexual reproduction- only requires one cell that simply splits or makes a copy of them selves Both occur in the human body

- Discovering Cells Development of the Cell Theory The cell theory states the following: All living things are composed of cells. Cells are the basic units of structure and function in living things. All cells are produced from other cells.

how the work of Hooke, Leeuwenhoek, Schleiden, Schwann, and Virchow contributed to scientific understanding of cells. Discovering Cells Hooke sees cells in cork. Leeuwenhoek sees many one-celled organisms. Schleiden concludes that all plants are made of cells. Schwann concludes that all animals (and all living things) are made of cells. Virchow proposes that new cells form only from cells that already exist. - Discovering Cells