Cells and Cell Theory: Grade 11 Biology

Cells and Cell Theory: Grade 11 Biology.

CELLS & THE CELL THEORY

 

Cells were discovered by Robert Hooke in 1665.

 

 

The Cell Theory states:

1.   All living organisms are composed of cells. They may be unicellular or multicellular.

2.   The cell is the basic unit of life.

3.   Cells arise from pre-existing cells.

 

The modern version of the Cell Theory includes the ideas that:

  • The activity of an organism depends on the total activity of its individual cells.
  • Heredity information (DNA) is passed on from cell to cell during cell division.
  • Energy flow (metabolism) occurs within cells.
  • All cells have the same basic chemical composition.

There are two different categories of cells:

1.   Prokaryotes lack a nucleus (though they do have DNA) and other membrane-bound organelles.  The two kingdoms of prokaryotes are Bacteria & Archaea

  1. Eukaryotes have distinct nuclei bound by a nuclear membrane and membrane-bound organelles (mitochondria, chloroplasts, lysosomes, rough and smooth endoplasmic reticulum, vacuoles).                 

There are four kingdoms of eukaryotes:    Animal, Plant, Fungus and Protist

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