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The Six Kingdoms: Chapter 17 Viruses: Microscopic particles that invade cells and cause disease Non-living because they do not grow or develop or carry out respiration; they can only reproduce inside living cells (called a host cell) Structure of a virus: Nucleic acid core: either DNA or RNA Capsid: outer protein coat Tail fibers: used to attach to host cell Viruses replicate in lytic or lysogenic cycles: (make a copy) Lytic cycle (active): Virus attaches to host cell Injects viral nucleic acid which destroys host’s DNA New viruses made inside the cell Host cell pops, releasing virus to infect other cells Lytic Cycle: Lysogenic Cycle: Viral DNA is joined with the host cell’s DNA (chromosomes) and can be passed on to daughter cells Virus is present but not active Explains why some diseases seem to go away only to reappear later and why some diseases don’t show up for many years Lytic and Lysogenic Cycle: Amoeba sisters … Examples of Viruses: HIV, flu, chicken pox, colds, hepatitis, measles Can you guess which diseases are caused by lysogenic cycles and lytic cycles? Vaccinations: Use weakened or dead form of a virus to create antibodies against the virus How do they work? 6 Kingdoms Archaebacteria Eubacteria Protist Fungi Plant Animal Bacteria: Archaebacteria: Prokaryotes Hetero/autotrophic Most ancient kingdom – 3.5 billion years Live in extreme environments (deep sea vents/swamps/no oxygen) Eubacteria: Prokaryotes Hetero/autotrophic Live everywhere (except extreme environments) Ex: Strep, Tetanus Structure of a Bacterial Cell: DNA Strong cell wall; prevents bursting DNA in single circular chromosome Plasmid: small ring of DNA Bacteria replicate by Binary Fission Binary Fission: Bacteria reproduce by dividing in half The importance of bacteria: Cause disease (pathogens) Ex: strep throat, tetanus, Lyme disease Fewer deaths from bacterial infections because of sanitation and hygiene The importance of bacteria: Recycle nutrients through decomposition Foods: cheese, yogurt Medicines: produce antibiotics to kill bacteria Antibiotic resistance Yes you need to know this!
