Transcript Document
Ch.26/27 • I. History of life • A. Earth formed about 4.5 billion years ago • 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 data shows 2 distinct groups of prokaryotes which split about 2 billion years ago. a. Archeabacteria b. Eubacteria • 2. 2.5 billion years ago production of oxygen created an aerobic environment. – a. More diversity exists between prokaryotes than all eukaryotes combined. Evolution video clip • 3. 2.2 billion years is the oldest fossils of eukaryotes – a. Mitochondria and chloroplasts were probably cells within cells. ( endosymbiosis) – b. RNA was probably the first genetic material • 4. Plants arose from green algae • 5. Fungi and animals arose from different groups of heterotrophic organisms. – a. Molecular evidence suggests animals are more closely related to fungi than to plants. – b. Oldest animal fossils are invertebrates from 700 million 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 still open 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 called ribozymes. Endosymbiosis • II. The major lineage's of life • A. The 5 kingdom system recognizes to fundamentally different types of cells, prokaryote and eukaryote. • 1. Kingdom Monera - lumps all bacteria together – 2. The plant, fungi and animal kingdoms are all multicellular organisms. • a. Plants are autotrophic • b. Fungi are heterotrophic but absorb their food • c. Animals are heterotrophic but ingest and digest • 3. The protist kingdom contains all the single celled eukaryotes and any that did not fit the other kingdoms. • B. The domains • 1. Superkingdoms _Bacteria, Archaea and Eukarya also referred to as domains Ch. 27 Prokaryotes • • • • • • I. The two main branches of prokaryotes A. Archea - means ancientthought to be most likely the earliest cells, but wrong. B. Eubacteria C. Shapes and sizes of prokaryotes 1. spheres- cocci (go ahead laugh now and get it out of your system) 2. rods- bacilli 3. helices Conjugation • D. Reproduction • 1. binary fission • 2.Transformation-_genes taken up from surroundings, like pGlo_ • 3.Conjugation-_transfer of genes from one prokaryote to another 4.Transduction-genes from virus acquired by bacteria • • E. Nutrition • 1. Photoautotrophs =Photosynthesis yields organic compounds 2. Chemoautotrophs - oxidize chemicals like, hydrogen sulfide and ammonia instead of using light for energy (only found in prokaryote nutrition) • 3. Photoheterotrophs - use light and organic compounds, can not use carbon dioxide. • 4. Chemoheterotrophs - must consume organic molecules. • 5. Cyanobacteria were the first to use water instead of hydrogen sulfide • Phylogeny • A. Archea • 1. Methanogens produce methane from hydrogen gas and 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 fixed for the plants to use – 2. Commensalism- Bacteria living in the vagina keep it basic to prevent yeast growth C. Diseases 1. Endotoxin- proteins on the prokaryote membranes » Exotoxin- proteins secreted by prokaryotes, ex botulism toxin- 1 gram can kill 1 million people • D. Research Exotoxins Lyme disease, or borreliosis, is an emerging infectious disease caused by bacteria from the genus Borrelia