Multicellular organisms constantly need to make more cells!

• Each minute your body needs to make ...oh...about 300 MILLION NEW CELLS! A cell spends most of its life working and growing, breaking down sugars, synthesizing proteins, enzymes, and other macromolecules, but cells inevitably wear out, break down and suffer injuries.
• In addition, as organisms grow and change, they need new cells to make more skin tissue, bone tissue, muscle tissue. These new cells can only come from one place: OTHER CELLS - through the process of cell division, or mitosis.
• For multicellular organisms (like us) cell division allows an organism to grow and develop from a single cell to trillions of cells, and also  to repair and replace cells worn out and used up by everyday life

On Thursday we will finish off our Mitosis unit by looking at photographs of real cells and trying to figure out which stage the cell is in.  By looking at the pictures above, you can see the difference between a diagram and the real thing.

HOMEWORK: Review chapter two - re-read sections 1-3 and answer the end of chapter review questions.  This chapter has covered the cell membrane and how materials pass through it, photosynthesis and respiration, and the cell cycle- how a cell duplicates itself.