![]() ![]() Prokaryotic Cells Prokaryotic cell walls -protect the cell and maintain cell shape Bacterial cell walls -may be composed of peptidoglycan -may be Gram positive or Gram negative Archaean cell walls lack peptidoglycan. Prokaryotic Cells Prokaryotic cells possess -genetic material in the nucleoid -cytoplasm -plasma membrane -cell wall -ribosomes -no membrane-bound organelles genetic material – in a nucleoid or nucleus 2. Electron microscopescan resolve structures that are 0.2nm apart.Īll cells have certain structures in common. Light microscopes can resolve structures that are 200nm apart. Microscopes are required to visualize cells. Sizes of Living Things Most cells are microscopic 5-100 microns Length of nerve cell 1 meter (m) Largest single cell Ostrich egg Cells specialized in absorption modified to greatly increase surface area per unit volume.As cell grows, volume increases faster than surface.Volume is living cytoplasm, which demands nutrients and produces wastes.Surface is membrane, across which cell acquires nutrients and expels wastes.Size restricted by Surface/Volume (S/V) ratio.Most much smaller than one millimeter (mm).Surface area-to-volume ratio: as a cell increases in size, the volume increases 10x faster than the surface area As cell size increases, it takes longer for material to diffuse from the cell membrane to the interior of the cell. German physician Rudolph Virchow in 1850’s Ĭell size is limited.All cells come only from preexisting cells.German zoologist Theodor Schwann in 1839.German botanist Matthais Schleiden in 1838.Originated from the work of biologists Schleiden and Schwann in 1838-9.Early studies of cells were conducted by - Mathias Schleiden (1838) - Theodor Schwann (1839) Cell Theory In 1665, the English scientist Robert Hooke coined the term “cellulae” for the small box-like structures he saw while examining a thin slice of cork under a microscope.Ĭells were discovered in 1665 by Robert Hooke. All cells are related by their descent from earlier cells.Cell structure is correlated to cellular function.The cell is the simplest collection of matter that can live. ![]()
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