7.1 Cell Discovery and Theory

Cell Discovery & TheorySection 7.1

1665 - Robert Hooke identified cells in cork and named them

Hooke 1683 - Anton van Leeuvenhoek 1st to describe living cells

1838 - Matthias Schleiden proposed plants were made of cells

1839 - Theodor Schwann concluded all living things are made of cells

1855 - Rudolf Virchow proposed all cells come from existing cells

Leeuvenhoek

Schleiden

Schwann

Virchow

Discovery of the Cell

Cell Theory1. all organisms are made of cells2. all existing cells are produced by other living cells3. the cell is the most basic unit of life

· vary in size and shape· tend to be microscopic· enclosed in a membrane· filled with cytoplasm

jellylike substance that contains dissolved molecular building blocks (proteins, nucleic acids, minerals, ions)· some cells have organelles

structures that perform a specific task in the cell

Cells in General

Prokaryotic Cells· NO nucleus· NO membrane-bound organelles· single-celled

· have a nucleus (houses genetic material - DNA)· have membrane-bound organelles· multicellular or single-celled

Eukaryotic Cells

7.1 Cell Discovery and Theory

Microscopes

· compound light microscopeuses lenses and light to magnify objectsmax magnification = 1000xocular (eyepiece) x lens = total magnificationoften uses stains to see cells better

· electron microscopetransmission electron microscope (TEM) uses

magnets to aim a beam of electrons through cells

max magnification = 500,000xspecimen must be dead, sliced very thin,

and stained with heavy metals