1. Cell Structure and Function

2. Cell Theory  Based upon work of Theodor Schwann, Matthais Schleiden and Rudolph Virchow.  All organisms are composed of cells  Cells are the basic units of structure and function in organisms  Cells come only from preexisting cells because cells are self- reproducing.

3. Why are most cells microscopic?  Cells need a large surface area to adequately exchange nutrients and wastes  surface-area-to-volume ratio  Total surface area (HxWxSxC) divided by total volume (HxWxLxC)  Some organelles have microvilli, villi and rugae to increase surface area

4. Microscopes  17 th century – Leewenhooke  Compound Light Microscope  Uses light rays and glass lenses to focus

5. Transmission Electron Microscope  Electrons pass through the specimen  Focus by magnetic lenses  Image projected on fluorescent screen

6. Scanning electron microscope  Narrow beam of electrons scan surface of specimen  Specimen is coated with metal layer  Secondary electrons given off by metal produce an image on a screen

7. Magnification and Resolution  Light microscope = approx. 1000x  TEM = hundreds of thousands  Difference is in illumination – wavelength of electrons is shorter than wavelength of light.  Greater resolution=greater detail  Resolution – minimum distance between 2 objects at which they can still be seen as two separate objects.  If humans eyes are set at 1.0, LM=500, EM = 100,000 resolving power.

8. Viewing advancements  To increase the contrast of a specimen, different types of light, staining and optical methods can be used.  Confocal microscopy – 3-D using laser beam.  Video enhanced contrast microscopy

9. Prokaryotic Cells  Lack nucleus and membrane bound organelles  Can cause disease, decompose and help to make foods/chemicals  Classified into 2 Domains

10. Structure  Bacillus – rod shaped  Coccus – sphere shaped  Spirilla – rigid twisted rods (called spirochetes if flexible)

11. Cell envelope  Plasma membrane – phospholipid bilayer embedded with proteins Regulates materials into and out of the cytoplasm Internal pouches – mesosomes – increase surface area for enzymes Cell wall – contains peptidoglycan – maintains shape Glycocalyx – layer of polysaccharides outside of cell wall, aids in protection from immune system and attachment capsule – if organized and hard to remove slime layer – if unorganized and easy to remove

12. Cytoplasm  Nucleoid region – houses the single circular strand of DNA  Plasmid – extrachromosomal piece of circular DNA used as vector in GE  Ribosomes  Inclusion body – stored nutrients

13. Cyanobacteria  Photosynthetic bacteria  Contain thylakoids in cytoplasm that contain chlorophyll that absorb solar energy to produce carbs.  Release oxygen

14. Appendages – made of protein  Flagella – locomotion, made of filament, hook and basal body  Fimbriae – small, bristlelike fibers on surface of cell, attachment  Sex Pili – rigid tubular structures, exchanging DNA - conjugation

15. Domain: Archaea  No peptidoglycan in cell wall  More diverse in shape  May be more closely related to eukaryotes because of biochemical make-up.  Live in extreme habitats, like those of long ago…