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Cell biology. Mrs. Stewart Central Magnet School Honors Biology. The discovery of cells. Robert Hooke Used an “early” Light Microscope to observe dead “cells” in bark of a Cork Oak tree.
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Cell biology Mrs. Stewart Central Magnet School Honors Biology
The discovery of cells • Robert Hooke • Used an “early” Light Microscope to observe dead “cells” in bark of a Cork Oak tree He coined the term “cells” because he described what he saw as “many little boxes” that reminded him of the cubicles, or cells, where monks live.
The discovery of cells • Anton Van Leeuwenhoek- • Made microscopes – able to grind lenses to increase magnification to 10x Hooke’s microscope • First to observe living cells • Spyrogyra genus – type of algae • Termed them Animalcules (protists)
The cell theory • All living organisms are composed of one or more cells • Matthias Schleiden – plants • Theodor Schwann – animals • Cells are the basic units of structure and function in an organism • Cells come only from the reproduction of existing cells • Rudolf Virchow
Microscopes • Microscopes are why scientists were able to stop speculating and start observing and exploring the “unseen” world of living and non-living things. • Microscopes helped scientists clarify our definition of life
Characteristics of life • Consist of cells • Cells display organization • Obtain and use energy to perform chemical reactions (metabolism) • Change through time (adapt) • Respond to their environment/stimulus • Reproduce • Growth and development • Homeostasis
Cell diversity • Shape • Cell shapes reflect the different functions of cells
Cell diversity • Size • A few cells are large enough to be seen by the “naked” eye • Surface area-to-volume ratio determines cell size. • All materials needed by the cell must enter and exit through the surface (cell membrane/wall) • Nutrients come in • Wastes are excreted out • As a cell becomes larger, the volume increases more than the surface area. There is a point where there is not enough surface area to sustain transport in/out of necessary materials to keep up with volume of cell.
Prokaryote vs eukaryote • Prokaryotes • Smaller • No nucleus, but a nucleoid • DNA is in one circular chromosome • No plasma membrane • No membrane bound organelles • Eukaryotes • Larger • Nucleus • Plasma membrane • Membrane bound organelles • Organelles carry out life processes within cell • DNA in multiple chromosomes within nucleus Pro = NO Eu = DO
Characteristics that distinguish plant cells from animal cells • Cell wall • Large central vacuole • plastids