Cells

Discovery of Cell

Antonie van Leeuwenhoek 1632-1723

* Developed microscopes for observing living organisms

* 1674 discovered live protist cells
* 1677 discovered spermatozoa
* 1682 discovered striated muscle fibers

Cell Theory

1. All living organisms consist of one or more cells.
2. Some organisms are unicellular, so cells are the fundamental unit of life.
3. New cells come from pre-existing cells by cell division.
4. Cells must show all the properties of life.
5. All cells are basically similar in chemical and structural composition.

Comparing Cell Sizes

* Mycoplasma 0.3-0.8 µm

* E. coli 1x2 µm

* Cyanobacteria 10 µm diam

Cell Structure: Nucleoid

Nucleoid - genome:- one circular DNA moleculeno histone protein association attached to cell membrane

  • Process called binary fission NOT mitosis!
  • Genome and copy are identical
  • Genome is haploid
  • There is no synapsis
  • There is no recombination
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