Cell biology (Discovery of cells) Flashcards
Discovery of cells
Followed from the work of Robert Hooke (1635-1703) done with an early model of the microscope
Robert Hooke
An english scientist an philosopher who contributed to the improvement of the microscope and explored the structure of snowflakes, fleas, lice, and plants
He coined the term “cell” from the latin word cella which means small room
Cell Theory
- All living organisms are composed of one or more cells
- The cell is the basic unit of life
(Schleiden and Schwann in 1839) - All cells only arise from pre-existing cells
(Rudolf Virchow 1855)
Prokaryotes
Were the only form of life on earth for millions of years until more complicated eukaryotic cells came into being through the process of evolution
Lack a defined nucleus
Features of prokaryotic cells
- Single cell organism
- Size 1-10 um
- No nucleus or organelles
- Ribosomes are present but small
- Reproduce asexually
- Genetic material found in nucleoid (like a nucleus) but not actually a true chromosome (DNA arranged in a circular fashion) plasmid
Examples of prokaryotic cells
- Archaea
- Bacteria
Eukaryotic cells
Organisms that have eukaryotic cells typically include protozoa (single celled eukaryotes), fungi, plants, and animals
Features of eukaryotic cells
- Size: typically 10-100 μm
- Nucleus and organelles
- Ribosomes are large
- Genetic material found in nuclear compartment and arranged as chromosomes