分类细菌和病毒的极光高中课件

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, Linnaeuss classification/taxonomy system expanded to organize living things further. This includes: Kingdom Phlyum Class Order Family Genus Species,Classification,Classification,Cladogram- a 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, Plants, Fungi, Protists *We 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 m) 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 part of the prokaryotic cell where the DNA is found Cell membrane innermost covering of the cell Cell wall 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) long, whiplike structure that moves bacteria Endospore A thick wall that encloses DNA; resistance structure enabling bacteria to survive harsh conditions Pili short, hair-like projection used to stick to other surfaces and for conjugation (exchange of genetic materials between bacteria) Cytoplasm 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 as either: Staph- clusters Strep-chains Spirilla Spiral-shaped,Bacteria-shapes,Bacteria- modes of nutrition,Heterotroph Consume other organisms: Clostridium Photoheterotroph Consume other organisms and can use light energy: Rhodobacter Photoautotroph 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 (microorganismviruses 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: vaccine- A 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 Cant 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),Bacteriophage,Helical,Spherical,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 des