1.  Objective: Explain the contributions made by early scientists that have contributed to the discovery of the cell.  1. Chapter 2 Tests  2. Hand in your Enzyme Labs  3. History of the Cell ◦ Vocabulary HW Check  4. Homework and Review ◦ Guided Reading Packet 7-1 ◦ Finish your Venn Diagram

2. CHAPTER 7

3.  The CELL is the basic unit of structure and function in living things.  CELL THEORY states ◦ 1. All living things are composed of cells ◦ 2. Cells are the basic units of structure and function in living things ◦ 3. New cells are produced from living cells

4.  1. Robert Hooke – viewed a thin slice of cork with an early compound microscope (1665) ◦ Name them cells because of a monastery’s tiny rooms. 2. Anton van Leeuwenhoek - observed tiny organisms in drops of pond water (1674) 3. Matthias Schleiden – Concludes that all plants are made of cells (1838)

5.  4. Theodor Schwann – Based upon Schleiden’s work, concludes animals are living so all animals are also made up of cells (1839)  5. Rudolph Virchow – proposes that all cells come from existing cells completing the cell theory (1855)

6.  6. Lynn Margulis – idea that certain organelles were once free living organisms ◦ Mitochondria and chloroplast both contain their own DNA. ◦ Endosymbiont Theory – Prokaryotic organisms (mitochondria and chloroplasts) were once free living but began a symbiotic relationship with larger multi-cellular organisms.

7.  Follow molecules through cells using fluorescent labels and light microscopy  Build 3-D models with confocal light microscopy ◦ Scans cells with a laser beam  Produce movies of cells as they grow, divide, and develop with High-resolution Video Technology

8.  Light microscope –resolution of image limited ◦ Unable to visualize tiny structures  Electron microscope – electron wavelengths much shorter than light wavelengths ◦ View details up to 1000x smaller than light microscope images TEM (Transmission electron microscope) – explores cell structures and large protein molecules SEM (Scanning electron microscope) – scans surface of a specimen. 3-D images. Must be in a vacuum and specimens must be preserved Unable to study living things

9.  Scanning probe microscope – traces the surface of a sample. ◦ Able to observe single atoms ◦ Can operate in open air ◦ Show samples in solution ◦ Study surfaces ◦ Image DNA, Protein molecules, and other important biological structures

10.  Both are surrounded by a cell membrane  Both contain DNA – the molecule that carries biological information

11.  Do not contain a nucleus  Smaller and simpler  Genetic material is free floating within the cell  Grow, reproduce, respond to environment, and some can move along surfaces or swim through liquids  Examples are bacteria

12.  Contain a nucleus that contains DNA separate from rest of cell  Larger and more complex  Dozens of Highly specialized membranes and structures  Single celled to large complex multi-cellular organisms  Plants, animals, fungi, and protists (algae)

13.  Describe to ways in which prokaryotes and eukaryotes are similar.

14.  Both are surrounded by a cell membrane  Both contain genetic material - DNA