Bacteria

Characteristics prokaryotic unicellular usually have locomotion reproduce sexually & asexually

Classification Kingdom Archaebacteria – “ancient bacteria” -able to live in extreme environments (thick mud, hot springs, salty environments) Kingdom Eubacteria – “true bacteria” -many are pathogenic (disease causing) -ex: E. coli

BACTERIA are classified according to:

1. Shapes of Bacteria

BASIC SHAPES: coccus-round, bacillus-rod, spirillum-spiral PREFIXES: diplo-pairs, tetra-fours, staphylo-clusters, strepto-chains

Identifying Prokaryotes 2. Structure of Cell Walls Two different types of cell walls are found in eubacteria. A method called gram staining tells them apart. Gram-positive bacteria have thinner cell walls with large amounts of peptidoglycan. Gram-negative bacteria have thick cell walls inside an outer lipid layer.

Nutrition autotrophic -photosynthesis – uses light -chemosynthesis - uses chemicals heterotrophic

3. Metabolic Diversity Prokaryotes are divided into two main groups: – Heterotrophs get their energy by consuming organic molecules made by other organisms. – Autotrophs make their own food from inorganic molecules.ex. Photoautotrophs and chemoautotrophs

Metabolic Diversity Three Types of Metabolism: a. Obligate aerobes-require a constant supply of oxygen. b. Obligate Anaerobes-Bacteria that live without oxygen because they may be killed by it. c. Facultative Anaerobes-Bacteria that can survive with or without oxygen.

Copyright Pearson Prentice Hall 4. Reproduction a. Binary Fission Binary fission is a type of asexual reproduction in which an organism replicates its DNA and divides in half, producing two identical daughter cells.

Copyright Pearson Prentice Hall Growth and Reproduction b. Conjugation During conjugation, a hollow bridge forms between two bacterial cells, and genes move from one cell to the other.

Growth and Reproduction c. Spore Formation In unfavorable growth conditions, many bacteria form spores. An endospore forms when a bacterium produces a thick internal wall that encloses its DNA and some of its cytoplasm.

binary fission

conjugation

Bacillus anthracis with endospore

Importance Beneficial: decomposers produce antibiotics break down sewer waste used in research used in food making form symbiotic relationships with humans (E. coli in intestine) nitrogen fixation

Importance Harmful: cause disease in humans cause disease in livestock cause disease in crops