CHAPTER Bacteria

Classifying Prokaryotes Divided into two different groups: 1. Eubacteria Larger of the 2 domains Live almost everywhere Cell wall contain peptidoglycan 2. Archaebacteria Lack peptidoglycan and have different membrane lipids DNA are more like eukaryotes than eubacteria Live in extremely harsh environments

Identifying Prokaryotes Prokaryotes are identified by characteristics such as shape, the chemical nature of their cell walls, the way they move, and the way they obtain energy. Shapes: Bacilli, cocci, and spirilla

Identifying Prokaryotes Cell Walls—Gram staining method is used to identify the two different types of cell walls in eubacteria. One stain is violet and the other red. Movement—identified by whether they move and how they move.  Some prokaryotes do not move at all  Some are propelled by flagella  Others lash, snake, or spiral forward  Others glide along on a layer of slimelike material they secrete.

Metabolic Diversity Best illustrates the diversity of bacteria. Ways in which they obtain energy 1. Heterotrophs—Obtain energy from foods they consume 1. Chemoheterotrophs—must take in organic molecules for both energy and a supply of carbon 1. Most animals, including humans, are chemoheterotrophs 2. Photoheterotrophs—these organisms are photosynthetic but they need to take in organic compounds as a carbon source.

Metabolic Diversity 2. Autotrophs—are able to produce their own energy/food 1. Photoautotrophs—use sunlight energy to convert CO2 and H2O to carbon compounds and oxygen 1. Found where light is plentiful 2. Ex. cyanobacteria 2. Chemoautotrophs—make organic compounds from carbon dioxide but do not require light as a source of energy. 1. Instead they use energy directly from chemical reactions involving ammonia, hydrogen sulfide, nitrites, sulfur, or iron.

Growth and Reproduction When conditions are favorable, bacteria can grow and divide at astonishing rates. If unlimited space and food were available and if all of its offspring divided every 20 minutes, in just 48 hours they would reach a mass 4000 times the mass of the Earth. Types of reproduction:  1. Binary Fission  2. Conjugation  3. Spore Formation

Importance of Bacteria Bacteria are vital to maintaining the living world. Some are producers that capture energy by photosynthesis. Others are decomposers that break down the nutrients in dead matter and the atmosphere. Still other bacteria have human uses. Decomposers—bacteria help the ecosystem recycle nutrients, therefore maintaining equilibrium in the environment

Importance of Bacteria Nitrogen Fixers—plants and animals depend on bacteria for nitrogen. Plants need nitrogen to make amino acids, the building blocks of proteins Nitrogen fixers convert nitrogen gas from the atmosphere into ammonia or other nitrogen compounds Human Uses—Clean-up (oil spills, poisons from water, etc.), mining, synthesis of drugs and chemicals. E. coli—bacteria in our intestines that aid in digestion.

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