Survey of Microorganisms Chapter 2: Survey of Microorganisms

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

Prokaryotes vs. Eukaryotes See table

Structure of prokaryotic vs. eukaryotic cell

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

Size of prokaroytes Look at handouts

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 http://bcs.whfreeman.com/thelifewire/content/chp27/27020.html

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

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

rRNA Phylogeny

Tree of life figure

Different mechanisms for energy and source of carbon for different organisms

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

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

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

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)

Metabolic Options for Conserving Energy

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

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

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

Phylogenetic Tree of Archaea

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