1. Survey of Microorganisms
Chapter 2:
Survey of Microorganisms

2. Microscopes We will discuss this in lab.
You can refer to your textbook for background information.

3. Prokaryotes vs. Eukaryotes
See table

4. Structure of prokaryotic vs. eukaryotic cell

5. Why are viruses different?
Do they have nucleic acids? If so, what kind?
Do they have plasma membranes or something else?

6. Size of prokaroytes
Look at handouts

7. Comparative ribosomal RNA sequencing has defined the three domains of life: Bacteria, Archaea, and Eukarya
Bacteria and archae are prokaryotes but archae are more closely related to eukaryotes

8. Origin of life Common ancestor – over 3.8 billion years ago
Three lines of descent leading to three domains
Archae
Bacteria
Eukarya
Archae and Eukarya more closely related than bacteria and Eukarya
Universal ancestor
(procell)
Bacteria
Eukarya
Archaea

9. Phylogeny The study of the evolutionary relation of distinct organisms
Phylogenetic relationship deduction
Trait based: compare the presence or absence of the trait
Molecular based: compare sequences from common molecules from organisms or interest
rRNA comparison
Tree of life

10. rRNA Phylogeny

11. Tree of life figure

12. Different mechanisms for energy and source of carbon for different organisms

13. Physiological Diversity of Microorganisms
Chemoorganotrophs
Obtain their energy from the oxidation of organic molecules
Chemolithotrophs
Obtain their energy from the oxidation or inorganic molecules
Process found only in prokaryotes

14. Physiological Diversity of Microorganisms
Phototrophs
Contain pigments that allow them to use light as an energy source
Oxygenic photosynthesis produces oxygen
Anoxygenic photosynthesis does not produce oxygen

15. Physiological Diversity of Microorganisms
All cells require carbon as a major nutrient
Autotrophs
Use carbon dioxide as their carbon source
Sometimes referred to as primary producers
Heterotrophs
Require one or more organic molecules for their carbon source
Feed directly on autotrophs or live off products produced by autotrophs

16. Physiological Diversity of Microorganisms
Nutritional type
Energy source
Carbon source
Photoautotroph
light
CO2
Photoheterotroph
Organic compounds
Lithoautotroph or lithotroph (chemolithotroph or chemoautotroph)
Inorganic compounds
(H2, NH3, NO2, H2S)
Heterotroph or chemoheterotroph (chemoorganotrophs)

17. Metabolic Options for Conserving Energy

18. Physiological Diversity of Microorganisms
Organisms that inhabit extreme environments are called extremophiles
Habitats include boiling hot springs, glaciers, extremely salty bodies of water, and high pH environments
Extremophiles thrive under environmental conditions in which higher organisms cannot survive

20. Extremophiles Many prokaryotes are extremophiles
No environment is devoid of prokaryotic life
Salt concentrations up to 30% for some
halophiles
pH 0-12
Acidophiles and alkaliphiles
Temps below 0 ºC to above 100 ºC
Psychrophiles and hyperthermophiles
High pressure
barophiles

21. Bacteria contain an enormous variety of prokaryotes
The Proteobacteria make up the largest division of Bacteria.
Gram-negative
E.G., E. coli, Pseudomonas and Salmonella
Cyanobacteria are relatives of gram-positive bacteria

22. Phylogenetic Tree of Archaea

23. Eukaryotic Microorganisms
Eukaryotic microorganisms are collectively known as protists
Major groups of protists are algae, fungi, protozoa, and slime molds