Mrs. Stewart Central Magnet School Honors Biology

 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.

 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)

 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 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

 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

 Shape  Cell shapes reflect the different functions of cells

 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.

Pro = NOEu = DO  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

 Cell wall  Large central vacuole  plastids