1. Chapter 17 Domain (Kingdom) Bacteria, Domain (Kingdom) Archaea, and Viruses

2. Nomenclature  Domain Bacteria Kingdom Bacteria – The True Bacterial Phylum Bacteriophyta – Class Cyanobacteriae – The Cyanobacteria (Blue-Green Bacteria) – Class Prochlorobacteriae – The Prochlorobacteria  Domain Archaea Kingdom Archaea – The Archaebacteria Methane Bacteria Salt Bacteria Sulfolobus Bacteria  Viruses  Viroids and Prions

3. Introduction  Fossils of bacteria - 3.5 billion years old  Fossils of first eukaryotic cells - 1.3 billion years old  Bacteria are found in astronomical numbers today. Approximately 10 million to 1 billion

4. Features of Kingdoms Bacteria and Archaea  All have prokaryotic cells. No nuclear envelopes Have long circular strand of DNA, ribosomes, membranes and plasmids No membrane-bound organelles Section of Prochloron cell

5. Features of Kingdoms Bacteria and Archaea  Nutrition: Primarily by absorption of food in solution through cell wall Some by chemosynthesis or by photosynthesis  Reproduction predominately asexual, by fission. Binary Fission - No mitosis, DNA strand duplicates and is distributed to new cells.

6. Features of Kingdoms Bacteria and Archaea Cellular Detail and Reproduction of Bacteria  Ribosomes present, but about half the size as those of eukaryotic cells.  Nucleoid - Single chromosome in form of ring  30 or 40 plasmids may be present. Plasmids - Small circular DNA molecules that replicate independently of chromosome

7.  Most bacteria less than 2 or 3 micrometers in diameter.  Occur primarily in three forms: Features of Kingdoms Bacteria and Archaea Size, Form, and Classification of Bacteria Cocci Spherical or elliptical Bacilli Rod-shaped or cylindrical Spirilla Helix or spiral

8.  Also classified by: Presence of sheath around cells, of hair-like or bud-like appendages, of endospores, of pili or of flagella Mechanisms of movement Biochemical characteristics Reaction of cell walls to dye – Gram-negative – Gram-positive Features of Kingdoms Bacteria and Archaea Size, Form, and Classification of Bacteria

9. Domain Bacteria (Kingdom Bacteria) – The True Bacteria  Phylum Bacteriophyta Class Bacteriae - Unpigmented, purple, and green sulfur bacteria – Most heterotrophic - Cannot synthesize own food o Majority saprobes - Food from nonliving organic matter « Responsible for decay and recycling of organic matter in soil o Some parasites - Depend on living organisms for food

10. Domain Bacteria – The True Bacteria  Phylum Bacteriophyta Autotrophic bacteria - Synthesize organic compounds from simple inorganic substances – Photosynthetic without producing oxygen o Purple sulfur bacteria - Bacteriochlorophyll pigments, use hydrogen sulfide o Purple nonsulfur bacteria - Bacteriochlorophyll pigments, use hydrogen o Green sulfur bacteria - Chlorobium chlorophyll pigments, use hydrogen sulfide – Photosynthetic and produce oxygen - Cyanobacteria and chloroxybacteria

11. Domain Bacteria (Kingdom Bacteria) – The True Bacteria  Phylum Bacteriophyta Autotrophic bacteria – Chemotrophic bacteria - Obtain energy from various compounds or elements through oxidation o Iron bacteria - Transform soluble iron to insoluble o Sulfur bacteria - Convert hydrogen sulfide gas to sulfur or sulfur to sulfate o Hydrogen bacteria - Use molecular hydrogen derived from anaerobic or nitrogen-fixing bacteria

12. Human Relevance of the Unpigmented, Purple, and Green Sulfur Bacteria  True bacteria and disease: Modes of access of disease bacteria: o Food poisoning and diseases associated with natural disasters « Cholera, dysentery, Staphylococcus and Salmonella food poisoning o Legionnaire disease o Botulism o Escherichia coli

13. Human Relevance of the Unpigmented, Purple, and Green Sulfur Bacteria  True bacteria and disease: Modes of access of disease bacteria: – Access through direct contact - Enter through skin or mucus membranes o Syphilis, Gonorrhea, Chlamydia, anthrax – Access through wounds o Tetanus and gas gangrene – Access through bites of insects and other organisms o Bubonic plague and Lyme disease

14. Human Relevance of the Unpigmented, Purple, and Green Sulfur Bacteria  True bacteria useful to humans: Biological control organisms – Bacillus thuringiensis (B t ) - Effective against caterpillars and worms o Destroys digestive tract – Bacillus popilliae - Effective against Japanese beetle grubs Bioremediation - Use of living organisms in cleanup of toxic waste and pollution Affect of Bacillus thuringiensis on tomato hornworm

15. Class Cyanobacteriae – The Cyanobacteria (Blue-Green Bacteria) Fresh and marine water, but not acidic water – Principal photosynthetic organisms in plankton Symbiotic with other organisms – Amoebae, sea anemones, fungi (producing lichens), cycads  Distribution - In diverse variety of habitats Pools and ditches, particularly if polluted Yellowstone

16. Class Cyanobacteriae – The Cyanobacteria (Blue-Green Bacteria)  Form, metabolism, and reproduction: Often in chains, or colonies held together by gelatinous sheaths Cells blue-green in color in about half of the approximately 1,500 species. Produce nitrogenous food reserve - Cyanophycin

17. Class Cyanobacteriae – The Cyanobacteria (Blue-Green Bacteria) In Nostoc and Anabaena, fragmentation often occurs at heterocyst. – Heterocyst - Large colorless, nitrogen-fixing cell

18. Class Cyanobacteriae – The Cyanobacteria (Blue-Green Bacteria)  Cyanobacteria, chloroplasts, and oxygen Thought that chloroplasts originated as cyanobacteria or prochlorobacteria living within other cells. Fossils of cyanobacteria, 3.5 billion years old, found in Australia. 3 billion years ago, cyanobacteria produced oxygen as by- product of photosynthesis. Oxygen accumulated in atmosphere, becoming substantial 1 billion years ago. As oxygen accumulated, other photosynthetic organisms appeared and forms of aerobic respiration developed. In last half billion years enough ozone formed to shield UV and for photosynthetic organisms to survive on land.

19. Kingdom Archaea (Domain Archaea) – The Archaebacteria  Metabolism is fundamentally different from other lines of bacteria.  Differ from true bacteria by unique sequences of bases in RNA, by lack of muramic acid in walls, and by production of distinct lipids  Methane bacteria Killed by oxygen Active only under anaerobic conditions – Energy derived from generation of methane gas from carbon dioxide and hydrogen.

20. Kingdom Archaea (Domain Archaea) – The Archaebacteria  Salt bacteria Metabolism enables these bacteria to thrive under extreme salinity. – Carry out simple photosynthesis with aid of bacterial rhodopsin. Lake Bonneville, Utah with very high salt content

21. Kingdom Archaea (Domain Archaea) – The Archaebacteria  Sulfolobus bacteria Occur in sulfur hot springs Metabolism allows these species to thrive at very high temperatures. – Mostly in vicinity of 80 o C (170 o F), some even higher Shape of ribosomes and chemistry of sulfolobus bacteria distinguishes them from other archaebacteria, true bacteria and eukaryotes.

22. Viruses  Size and structure: Represent interface between biochemistry and life – Lack cytoplasm or cellular structure o Do not grow by increasing in size or dividing o Do not respond to external stimuli o Cannot move on their own o Cannot carry on independent metabolism o Inside living cells, they express their genes and use cellular machinery to produce more virus particles. – About size of large molecules, 15-300 nanometers Papavoviruses in a human wart

23. Viruses  Viral reproduction: Viruses replicate at the expense of their host cells. – Attach to susceptible cell – Penetrate to cell interior – DNA or RNA dictates synthesis of new molecules. – New viruses released from host cell. o Host cell dies. – Some can mutate very rapidly. o As a result, new vaccines need to be developed. Bacteriophage replication

24. Viruses  Human relevance of viruses: Retrovirus - A virus with two identical nuclear strands o Evolves extremely quickly « About a million times faster than cellular organisms o AIDS

25. Viroids and Prions  Viroids - Circular strands of RNA that occur in nuclei of infected plant cells Transmitted from plant to plant via pollen or ovules – Cause more than a dozen plant diseases  Prions - Appears to be particles of protein that cause diseases of animals and humans Believed to cause disease by inducing abnormal folding of proteins in brain, resulting in brain damage – Cruetzfeldt-Jacob disease