Transcript BACTERIA
The virus “For about 100 years, the scientific community has repeatedly changed its collective mind over what viruses are. First seen as poisons, then as life-forms, then biological chemicals, viruses today are thought of as being in a gray area between living and nonliving: they cannot replicate on their own but can do so in truly living cells and can also affect the behavior of their hosts profoundly. The categorization of viruses as nonliving during much of the modern era of biological science has had an unintended consequence: it has led most researchers to ignore viruses in the study of evolution. Finally, however, scientists are beginning to appreciate viruses as fundamental players in the history of life.” What is a virus??? Particles of nucleic acid, proteins, and in some cases, lipids Reproduce only by infecting other cells Vary widely in size and structure BACTERIOPHAGE The Common Cold Virus HIV Virus “life” cycle retroviruses All viruses enter living cells and, once inside, use the machinery of the infecte cell to produce more viruses How a Virus Invades Your Body BACTERIA microscopic life that covers nearly every square centimeter of the Earth yet was completely unknown until the invention of the microscope “ What are bacteria??? • • • • Prokaryotic cells- which means what exactly? Smallest and most common microorganism Range in size from 1 to 5 micrometers (unless you are a Epulopiscium fisheloni in which case you are much larger) Often thought of as bad guys but really not so much Classification of bacteria Eubacteria • • • Largest group, quite varied Find living almost everywhere Cell wall made of a carbohydrate called “Peptidoglycan” The cell wall: 1. protects from injury 2. determines shape of bacteria ARCHAEBACTERIA • Cell wall lacks peptidoglycans • DNA sequences more similar to that of Eukaryotes suggesting they may be the early ancestors of eukaryotic organisms • Able to live in very harsh environments such as salt water and hot springs. • Methanogens live in oxygen-free environments such as thick mud and intestines of animals methane gas We can identify bacteria by their : 1. Shape a. Cocci b. Bacilli c. Spirilli 2. Nature of Cell Wall GRAM + (with peptidoglycan) GRAM - (without peptidoglycan) 3. Movement- if and how flagella or slime Flagellar Motion Bacteria can be heterotophic or autotrophic when they eat. Bacteria can be aerobic and carry out respiration, anaerobic causing fermentation or a Bit of both- facultative Bacteria make more bacteria through: Binary Fission b.f. Spore Formation Conjugation Significance of bacteria 1. 2. 3. 4. 5. 6. 7. 8. Capture energy through photosynthesis Decomposers Nitrogen-fixers Produce food and beverages “Eat” small oil spills Purify H2O Synthesize drugs, chemicals Produce vitamins in human gut And sometimes they make us sick… Pathogens 120,000 to 150,000 different species of bacteria are thought to exist. But less than 1% of these make us sick Antibiotic resistance