4

CHAPTER

67

Prokaryotic Cells

and Eukaryotic Cells

What do you and Athletes Foothave in common? You’ll recall from Chapter 1
that Tinea pedisis the scientific name for athlete’s foot and that it is caused by
the Trichophytonfungus. Both of you are alive. Sometimes it’s hard to imagine
that microorganisms are alive because we can’t see them with our naked eye—
although they make their presence known to us in annoying ways.
Humans, Trichophyton, and all other living things are alive because they
carry on the six life processes, something non-living things do not do. The six life
processesrequire a living thing to:

• Metabolize.Breakdown nutrients for energy or extract energy from the
  environment.


• Be responsive. React to internal and external environmental changes.


• Move.Whether it is the entire organism relocating within its environment,
  cells within that organism or the organelles inside those cells.


• Grow. Increase the size or number of cells.


• Differentiate. The process where cells that are unspecialized become spe-
  cialized. (An example would be a single fertilized human egg, developing
  into an individual). Prokaryotic cells do not differentiate.


• Reproduce. Form new cells to create a new individual.

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