Chapter 5 The Microbial World

Primary Producers Autotrophs- That convert inorganic carbon, usually in the form of CO2 in to organic compounds.

Prokaryotes Cells enclosed by a protective cell wall. Lack a nucleus and membrane bound organelles. Some have circular DNA (plasmids).

Domain Bacteria Prokarya Have many shapes Coccus- spherical Bacillus- rod-shaped Spirillum- spiral

Bacteria Structure All Bacteria have a cell wall. Some bacteria have capsules that are covered with a slimy mucous for extra protection.

Interesting fact 250,000 bacteria would fit on the period at the end of this sentence.

Bacteria grow in great numbers where detritus (dead organic matter) is present. Decay bacteria- break down organic matter and recycle it into the environment. Some are even used to clean up oil spills on the water.

Cyanobacteria Once called blue-green algae. They are photosynthetic. Contain the pigments chlorophyll a- green phycocyanin- blue phyoerythrin- red They were among the first organisms on earth and contributed to the oxygen in the atmosphere.

Cyanobacteria

Stromatolites Massive calcareous (calcium carbonate) mounds formed by cyanobacteria.

Stromatolites

Cyanobacteria can be found in a variety of environments even in polar bear hair!

Endolithic- burrow into rocks and coral skeletons. Planktonic- species can reproduce rapidly and cause red tides. (Give swimmers rashes.

Red Tides

Red Tide Rash

Epiphytes- bacteria that live on algae or plants. Endophytes- bacteria that live in algae or plants.

Domain Archaea Simplest and most primitive life forms. Live in extreme environments like hydrothermal vents, the Dead Sea, and anaerobic environments. Also found in other habitats.

Archaeabacteria are classified by their nucleic acids. (DNA and RNA)

Metabolism Some bacteria are autotrophic- photosynthesize or chemosynthesize. Some are heterotrophic- respirate after consuming or decomposing. Ex: Some anaerobic bacteria grow in sediments devoid of oxygen called-anoxic sediments.

Some benthic bacteria are nitrogen fixers and convert Nitrogen gas N2 into Ammonia (NH4) and Nitrates (NO3) for later use by primary producers.