Classification, Bacteria, and Viruses notes
advertisement
CLASSIFICATION, BACTERIA, AND VIRUSES Biology Classification Taxonomy is: the science of naming and classifying organisms Linnaeus developed a two-word naming systems called binomial nomenclature. Each species is assigned a two-part scientific name. Written in italic, with just the first word capitalized First word: Genus Second word: species For examples, humans are Homo sapiens Classification Overtime, Linnaeus’s classification/taxonomy system expanded to organize living things further. This includes: Kingdom Phlyum Class Order Family Genus Species Classification Classification Cladograma model used by evolutionary biologists to represent evolutionary history among species Clade- a group of species that includes a single common ancestor and all descendants of that ancestor. Derived character- a trait that arose in the most recent common ancestor of a particular lineage and was passed along to its descendants. Classification Classification Classification has broaden beyond kingdoms to domains: Bacteria Archaea Eukarya Domain Bacteria Characteristics: Unicellular prokaryotes Peptidoglycan cell wall, cell membrane, ribosomes No membrane-bound organelles Naked DNA, single circular chromosome Asexual reproduction= binary fission Heterotrophs, photoautotrophs, chemoautotrophs Rods, spheres, spirals: Gram positive and gram negative Domain Bacteria Domain Bacteria Examples include: Bacillus, E. Coli, Streptococcus Domain Archaea Characteristics Unicellular prokaryotes Cell wall (no peptidoglycans), cell membrane, ribosomes, no membrane-bound organelles DNA + histone proteins, single circular chromosome Asexual reproduction = binary fission Extremophiles: halophiles, thermophiles, methanogens Domain Archaea Examples: Methancoccus, Halobacterium, Thermoproteus Domain Eukarya Examples: Animals, *We Plants, Fungi, Protists will explore each Kingdom in more detail throughout the remainder of the year Prokaryotes All bacteria are prokaryotes unicellular organism that lack a nucleus. small cells (about 1-10 µm) that do not have membrane-bound organelles Found in bacteria and archaebacteria Prokaryotes Bacteria Surrounded by cell wall which contains peptidoglycan Archaebacteria Look similar to bacteria Lack peptidoglycan in cell walls Live in harsh environments Bacteria Prokaryotic Cell Structures: Nucleoid region – Cell membrane – innermost covering of the cell Cell wall – part of the prokaryotic cell where the DNA is found outside of cell membrane Capsule – outside of the cell wall, protective covering (not all bacteria have it) Bacteria Prokaryotic Cell Structures (continued): Flagella (sing. Flagellum) – Endospore short, hair-like projection used to stick to other surfaces and for conjugation (exchange of genetic materials between bacteria) Cytoplasm – A thick wall that encloses DNA; resistance structure enabling bacteria to survive harsh conditions Pili – long, whiplike structure that moves bacteria jelly-like fluid that dissolves substances and holds organelles Ribosomes – organelles that make proteins in the cytoplasm Bacteria Bacterial cell walls In bacteria, the cell wall consists of a protein/carbohydrate complex called carbohydrate called peptidoglycan. They are classified based on their cell walls: Gram positive bacteria More peptidoglycan in cell walls Appear purple under the microscope after gram stain Gram negative bacteria Have less peptidoglycan in cell walls Have outer membrane Apper pink under the microscope after gram stain Bacteria- shapes Bacilli Rod-shaped Cocci Spherical-shaped Staph- clusters Strep-chains Spirilla Spiral-shaped as either: Bacteria-shapes Bacteria- modes of nutrition Heterotroph Photoheterotroph Consume other organisms and can use light energy: Rhodobacter Photoautotroph Consume other organisms: Clostridium Use light energy to make carbon compounds; Cyanobacteria Chemoautotroph Use chemicals, like ammonia and hydrogen sulfide, to obtain energy; Nitrogen-fixing bacteria Bacteria- Aerobic, Anaerobic, and Facultative Anaerobes Aerobic Need oxygen to live Anaerobic Cannot live with oxygen Facultative anaerobes Can live with or without oxygen Bacteria- Binary Fission Binary fission Process by prokaryotes reproduce by cell division. Steps: Duplication of chromosomes and separation of copies. Cell elongates Divides into two daughter cells Bacteria- Binary Fission Bacteria and Disease Pathology- the study of disease caused by pathogens (microorganism—viruses or prokaryotes– that cause disease) Bacteria and disease Bacteria cause disease by destroying living cells or by releasing chemicals that upset homeostasis. Damaging host tissue Releasing toxins Bacteria and Disease Bacteria can be controlled via: Physical removal Disinfectants Food storage Food processing Sterilization by heat Bacteria and Disease Bacterial diseases can be treated via Antibiotics Blocks the growth and reproduction of bacteria Examples: penicillin, streptomycin, and tetracycline Bacteria and Disease Prevention of a bacterial disease via: vaccineA preparation of weakened or killed pathogens or inactivated toxins that prompt the body to produce immunity to a specific disease upon injection. Virus Virus A nonliving particle made of proteins and nucleic acids. Can reproduce only by infecting living cells. Have no cytoplasm or organelles Cannot carryout metabolism or homeostasis Can’t grow like cells. Virus Viruses consist of… Capsid- protein coat surrounding a virus Some viruses have an envelop that surrounds the capsid (Influenza) Nucleic acids (either DNA or RNA) Virus Shapes Helical- Tobacco Mosaic Virus (contains RNA) Polyhedral- Herpes (contains DNA) , Chicken Pox (contains DNA), Polio (contains RNA) Spherical (enveloped)- Influenza (contains RNA) Bacteriophage- T4 (contains DNA) Helical Spherical Bacteriophage Virus Viral Infections In order to infect a cell, a virus must be able to recognize it. Viruses must bind the proteins on their capsid specifically to the proteins on their specific host. Viruses then “trick” the cell to take in its genetic material. Viruses will then make multiple copies of themselves inside the cell, ultimately destroying the cell. Virus Viral Infections can take place in two ways Lytic infection Lysogenic infection Virus Lytic Infection The virus infects a cell, it replicates, and the new viruses burst or “lyse” from the cell. Virus Lysogenic Infection host cell is not immediately taken over The virus infects a cell, the viral DNA integrates with host DNA where it may stay for a long period of time. The viral DNA multiplies as the host cells multiply. Eventually, it will become lytic, and the viruses will burst from the cell. Viruses and Disease Viruses cause disease by directly destroying living cells or by affecting cellular processes in ways that upset homeostasis. Diseases include: Common cold Influenza AIDS Chicken pox Hepatitis Wes Nile Virus HPV (Human papillomavirus) Viruses and Disease Ways to fight viruses Hygiene Washing hands, avoiding contact with sick individuals, coughing or sneezing into a tissue or your sleeve Vaccinations Exposure to inactive forms of the virus that prompt the body to produce immunity to a specific disease upon injection. Vector control West Nile Virus is carried by mosquitoes (the vector). Controlling the population mosquitoes could eliminate the spread of the virus. Antiviral Attack drug therapy virual enzymes that in turn slow down or stop the infection cycle of the virus.
