7-1 Life is CELLULAR

Federoff

Key Questions

• What is the cell theory?• How do microscopes work?• How are prokaryotic and eukaryotic cells

different?

Discovery of the Cell• Microscopes allowed a new

world to open up.– Started in the late 1500’s with

eyeglass makers• Robert Hooke (1665)– Englishman– Studied Cork – Termed cells “cells” because of

their resemblance to monastery rooms.

Discovery of the Cell (cont.)

• Anton van Leewenhoek– Same time as Hooke– Documented first LIVING and moving cells we

know today as microorganisms

Cell Theory• Schleiden, Schwann and Virchow – Scientists contributors

• States that:– All living things are made of cells– Cells are the basic structure and function in all living things– New cells come from existing cells

Exploring the cell - Microscopes

• Light Microscopes– Have an objective and eyepiece (ocular) lens– Compound magnification– LIMITS• Detail• 1000x magnification• Requires a stain• Thin specimen for light to pass through

Microscopes (cont.)

• Electron Microscopes– Higher Resolution– Can view DNA and Viruses– Scanning and Transmission– LIMITS• Must chemically preserve• Needs to be DEAD• Need to add false color

Scanning

Transmission

Cell Types

• Lots of variety in size, shape and function• All contain DNA and a cell membrane• 2 Types– Eukaryotes – have DNA in a nucleus– Prokaryotes – Do not have a nucleus to contain

their DNA

Prokaryotes• Smaller• Simpler• Doesn’t separate DNA with a nucleus• Unicellular• Ex. Bacteria

Eukaryotes

• Larger• More complex• DNA in nucleus• Great variety• Unicellular or Multicellular• Ex. Your cells