Cell Theory

Microscopes and Cells: History Don’t copy down this slide – just listen Microscopes and Cells: History In 1663, __________ coined the term “cells” 10 years later, _________________ observed bacteria and protozoa In 1833, __________ observed and coined the term “nucleus” Robert Hooke Anton van Leeuwenhoek Robert Browne No nucleus DNA in nucleoid region

Guten Tag, Dr. Shwann Cell Theory: History Guten Tag, Dr. Schleiden It appears we have come up with a very similar theory… In 1838 (and 1839) German scientists, ________________ & ________________ independently came up with the “Cell Theory” Matthias Schleiden What shall we call this theory? Theodore Schwann

Cell Theory All living things are made up of one or more cells. Cells are the smallest basic unit of life, with structure, function, and organization.

all cells must come from pre-existing cells. In 1855, German physician Rudolph Virchow discovered that… all cells must come from pre-existing cells. Please add the above as point #3 to the cell theory

How big are cells? Eukaryotic cells include _______ & _______ cells. Most eukaryotic cells are between __ and ___ m. What is the limit of the light microscope? Why? What is used to see smaller objects? __________________ plant animal 10 100 0.2 m It is limited to the visible light spectrum Electron Microscopes

Electron Microscopy ___________ Electron Microscopes (TEM) emit light through a thin piece of heavy metal ion stained tissue ________ Electron Microscopes (SEM) reflect light off of a piece of heavy metal ion stained tissue Transmission Scanning

Prokaryotic Cells (cells without a nucleus) for ex. bacteria Label this diagram in your handout Cell Wall Circular DNA Ribosomes Plasma Membrane Cytoplasm Cilium Cilia Flagella Flagellum TEM of a bacterium

Eukaryotic Cells: cells with a nucleus (include plant and animal cells) Nucleus w/DNA wound in strands Plant cell Ribosome (dots) for making proteins Membrane organelles (more membranes within the cell Animal cell All organelles are suspended in the cytoplasm of both cells Plasma Membrane Cell Wall (not in animals cells)

Differences and similarities between Prokaryotes and Eukaryotes Prokaryotes Eukaryotes Has a nucleus Has “membrane” organelles or structures inside the cell Larger than prokaryotes 10-100 m (micrometers) in size Several DNA packaged into strands called chromatin No nucleus No “membrane” structures inside the cell Small 1-10 m (micrometers) in size One circular piece of DNA Plasma Membrane Cytoplasm DNA or genetic material Ribosomes that make protein