Bacteria Eubacteria n n n Larger of two

Bacteria

Eubacteria n n n Larger of two bacteria kingdoms Live almost everywhere Many types of metabolism n n Heterotrophs Photosynthetic Autotrophs Chemosynthetic Autotrophs Cell walls contain peptidoglycan, a carbohydrate

Archaebacteria n n Lack peptidoglycan in their cell walls Different membrane lipids DNA sequence is different Live in extremely harsh environments n n n Oxygen-free Concentrated salt water Hot springs

Identifying Prokaryotes n Prokaryotes are identified by characteristics such as: n n Shape (round, rod, spiral) Chemical nature of cell walls (Gram – or +) The way they move (none, flagella, slime) The way they use energy

Bacterial Shapes and Arrangements

Gram Stain Procedure

Diversity of Metabolism n n Heterotrophs (most) Autotrophs (some) n n n Photoautotrophs Chemoautotrophs Obligate aerobes Obligate anaerobes Facultative anaerobes

Bacterial Growth and Reproduction n In favorable conditions, some bacteria divide as often as every 20 minutes! If unlimited space and food were available to every bacterium, in 48 hours they and their offspring could reach a mass of 4000 x the mass of Earth! Fortunately, availability of food and the production of waste products keeps bacterial growth in check.

Bacterial Reproduction n n Bacteria reproduce asexually through a process called binary fission. Many bacteria also have a simple form of sexual reproduction called conjugation.

Endospores n n n Hard outer coverings called endospores are formed by many bacteria when they face unfavorable environmental conditions. Endospores are resistant to drying out, boiling, and many chemicals. They can remain dormant for months or even years!

Bacteria are “Survivors!” n n Some of the oldest known fossils are of bacteria Broad variety of metabolic pathways Endospores Asexual and sexual reproduction

Importance of Bacteria n n n n Nitrogen fixation Decomposition Photosynthesis Foods: vinegar, yogurt, butter, cheese, pickles, etc. Synthesize drugs and chemicals Make vitamins Digest petroleum

Review Question #1 n How are eubacteria and archaebacteria alike and different?

Review Question #2 n Describe some adaptations of bacteria.

Review Question #3 n Bacteria are essential to life. Why do you think this statement is true?