Cells - Botany

Cells -

  • Smallest living unit

  • Most are microscopic


Discovery of Cells -

  • Robert Hooke (mid - 1600’s)

  • Observed sliver of cork

  • Saw “row of empty boxes”

  • Coined the term cell


Cell Theory -

  • (1839) Theodor Schwann (animals) & Matthias Schleiden (plants)

  • “all living things are made of cells”

  • (50 yrs. later) Rudolf Virchow

“all cells come from cells”


Principles of Cell Theory -

  • All living things are made of cells

    • Schleiden (plants) & Schwann (animals)

  • Smallest living unit of structure and function in all organisms is the cell

    • Hooke

  • All cells arise from preexisting cells

(this principle discarded the idea of 

spontaneous generation; Virchow)


Characteristics of all Cells -

  • Surrounding membrane

  • Cytoplasm – cell contents in thick fluid

  • Ribosomes (protein synthesis)

  • Control center with DNA



Cell Types -

  • Prokaryotic 

  • Eukaryotic



Prokaryotic Cells

  • First cell type on earth

  • Cell type of Bacteria and Archaea



Prokaryotic Cells -

  • No membrane-bound nucleus

  • Nucleoid = region of DNA concentration

  • No membrane-bound organelles

  • Ribosomes

  • Cell walls



Eukaryotic Cells -

  • Include fungi, protists, plant, and animal cells

  • Membrane-bound organelles

  • Nucleus



Organelles

  • Cellular machinery 

  • Two general kinds

    • Derived from membranes

    • Bacteria-like organelles