Ch.26/27
•I. History of life
•A. Earth formed about 4.5 billion yearsago
•B. Life began a few 1,000,000 years later
•1. Metabolic activity found in 3.5 billion year old rocks
•2. 3.5 billion year old fossils have been found
•C. Major happenings
•1. RNA sequence datashows 2 distinct groupsof prokaryotes whichsplit about 2 billionyears ago.
a. Archeabacteria
b. Eubacteria
•2. 2.5 billion yearsago production ofoxygen created anaerobic environment.
–a. More diversityexists betweenprokaryotes than alleukaryotescombined.
•3. 2.2 billion years is the oldest fossils ofeukaryotes
–a. Mitochondria and chloroplasts were probably cellswithin cells. ( endosymbiosis)
–b. RNA was probably the first genetic material
•4. Plants arose from green algae
•5. Fungi and animals arose fromdifferent groups of heterotrophicorganisms.
–a. Molecular evidence suggests animals are moreclosely related to fungi than to plants.
–b. Oldest animal fossils are invertebrates from 700million years ago.
•6. Plants and fungi came on land about 475 million years ago
•There is a lot of speculation on how life first came to be and the subject is stillopen to debate.
•D. RNA: the first genetic material
•1. Now it is DNA->RNA->protein
2. A more simple version would have been RNA-> protein
–a. RNA has been found to act like a catalyst and these are calledribozymes.
Endosymbiosis
•II. The major lineage's of life
•A. The 5 kingdom system recognizes tofundamentally different types of cells,prokaryote and eukaryote.
•1. Kingdom Monera - lumps all bacteriatogether
–2. The plant, fungi and animal kingdoms are allmulticellular organisms.
•a. Plants are autotrophic
•b. Fungi are heterotrophic but absorbtheir food
•c. Animals are heterotrophic but ingestand digest
•3. The protist kingdom contains all thesingle celled eukaryotes and any thatdid not fit the other kingdoms.
•B. The domains
•1. Superkingdoms _Bacteria, Archaea andEukarya also referred to as domains
Ch. 27Prokaryotes
•I. The two main branches ofprokaryotes
A. Archea - means ancient-thought to be most likelythe earliest cells, butwrong.
•B. Eubacteria
•C. Shapes and sizes ofprokaryotes
•1. spheres- cocci (goahead laugh now and get it outof your system)
•2. rods- bacilli
•3. helices
•D. Reproduction
•1. binary fission
•2.Transformation-_genes taken upfrom surroundings, like pGlo_
•3.Conjugation-_transfer of genesfrom one prokaryote to another
4.Transduction-genes from virusacquired by bacteria
•E. Nutrition
•1. Photoautotrophs =Photosynthesis yields organic compounds
• 2. Chemoautotrophs - oxidize chemicals like, hydrogen sulfide andammonia instead of using light for energy (only found inprokaryote nutrition)
•3. Photoheterotrophs - use light and organic compounds, can not usecarbon dioxide.
•4. Chemoheterotrophs - must consume organic molecules.
•5. Cyanobacteria were the first to use water instead ofhydrogen sulfide
•Phylogeny
•A. Archea
•1. Methanogens produce methane from hydrogen gasand carbon dioxide- oxygen is poison to them
•2.Halophiles live in saline places.
•3.Thermophiles like high heat
•B. Bacteria
•1. Make up the majority of prokaryotes
•III. Importance of prokaryotes
•A. Decomposers- they return elements to the environment
•B. Symbiosis- relationships _between organisms
–1. Mutualism- Rhizobium and legumes, nitrogen is fixedfor the plants to use
–2. Commensalism- Bacteria living in the vagina keep itbasic to prevent yeast growth
•C. Diseases
•1. Endotoxin- proteins on the prokaryote membranes
»Exotoxin- proteins secreted by prokaryotes, exbotulism toxin- 1 gram can kill 1 million people
•D. Research
Lyme disease, or borreliosis, is an emerging infectious diseasecaused by bacteria from the genus Borrelia
