1. Bacteria and Viruses Chapter 18

2. Bacteria Prokaryotes-single-celled organisms without an nucleus Prokaryotes-single-celled organisms without an nucleus Two kingdoms Two kingdoms Eubacteria-live anywhere; cell wall of peptidoglycan Eubacteria-live anywhere; cell wall of peptidoglycan Archaebacteria-live in extreme environments; no peptidoglycan; most live without oxygen Archaebacteria-live in extreme environments; no peptidoglycan; most live without oxygen

3. Prokaryotes Identified by Identified by Shape Shape Cocci-round Cocci-round Spirilli-spiral shaped Spirilli-spiral shaped Bacilli-rod Bacilli-rod Chemical nature of cell walls Chemical nature of cell walls Thick peptidoglycan stains purple; thin walls stain pink Thick peptidoglycan stains purple; thin walls stain pink Movement: flagella, twisting, secretions Movement: flagella, twisting, secretions Method of obtaining energy Method of obtaining energy

4. To return to the chapter summary click escape or close this document. Typical Bacteria Cell

5. Metabolic diversity Heterotrophs Heterotrophs Chemoheterotrophs-take in organic chemicals for energy and carbon Chemoheterotrophs-take in organic chemicals for energy and carbon Photoheterotrophs-photosynthesize for energy but take in chemicals for carbon Photoheterotrophs-photosynthesize for energy but take in chemicals for carbon Autotrophs Autotrophs Photoautotrophs-use light for energy and carbon Photoautotrophs-use light for energy and carbon Chemoautotrophs-use chemicals for energy and carbon Chemoautotrophs-use chemicals for energy and carbon

6. Releasing energy Occurs by cell respiration, fermentation, or both Occurs by cell respiration, fermentation, or both Obligate aerobes-require oxygen for survival Obligate aerobes-require oxygen for survival Obligate anaerobes-do not need oxygen and are often killed in oxygen Obligate anaerobes-do not need oxygen and are often killed in oxygen Facultative anaerobes-can live with or without oxygen Facultative anaerobes-can live with or without oxygen

7. Bacterial reproduction Binary fission-1.cell doubles in size; 2.replicates its DNA; 3.cell divides in half to make 2 new cells (identical) Binary fission-1.cell doubles in size; 2.replicates its DNA; 3.cell divides in half to make 2 new cells (identical) Conjugation-1.one bacterium hooks to another bacterium with a pilus; 2. genes are exchanged between the two cells Conjugation-1.one bacterium hooks to another bacterium with a pilus; 2. genes are exchanged between the two cells Spore formation-thick coverings or endospores form to protect the bacterium in unfavorable conditions Spore formation-thick coverings or endospores form to protect the bacterium in unfavorable conditions

8. Importance of bacteria Help maintain the living world Help maintain the living world Decomposers-recycle nutrients in the environment (decaying organisms, sewage) Decomposers-recycle nutrients in the environment (decaying organisms, sewage) Nitrogen fixers-convert gaseous nitrogen to a useable form Nitrogen fixers-convert gaseous nitrogen to a useable form Industrial uses-used to make food products, remove waste, digest petroleum, mine minerals Industrial uses-used to make food products, remove waste, digest petroleum, mine minerals

9. Viruses Particles of nucleic acid, protein, and sometimes lipids Particles of nucleic acid, protein, and sometimes lipids Reproduce only by infecting other cells Reproduce only by infecting other cells Differ in size and structure Differ in size and structure Highly specific in cells they infect Highly specific in cells they infect

10. Typical virus structure Capsid- protein coat, includes proteins that enable virus to enter a host cell Capsid- protein coat, includes proteins that enable virus to enter a host cell Nucleic acid core- made of DNA or RNA but not both Nucleic acid core- made of DNA or RNA but not both

11. To return to the chapter summary click escape or close this document. Influenza Virus

12. To return to the chapter summary click escape or close this document. T4 Virus

13. Viral infection: Lytic 1. virus attaches to outside of cell and inserts its nucleic acid into the host 1. virus attaches to outside of cell and inserts its nucleic acid into the host Viral DNA destroys host DNA and takes over the cells metabolism Viral DNA destroys host DNA and takes over the cells metabolism Host is used to make new viral particles, DNA and protein Host is used to make new viral particles, DNA and protein Host bursts open to release new viruses Host bursts open to release new viruses

14. Viral infection: Lysogenic 1. virus attaches to host and inserts its nucleic acid 1. virus attaches to host and inserts its nucleic acid Viral DNA is inserted into the host DNA and is replicated with host DNA for an unlimited amount of time Viral DNA is inserted into the host DNA and is replicated with host DNA for an unlimited amount of time Viral DNA removes itself from host DNA and destroys host DNA Viral DNA removes itself from host DNA and destroys host DNA New viral particles are produced New viral particles are produced Cell bursts open and releases new viruses Cell bursts open and releases new viruses

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16. Retroviruses Contain only RNA Contain only RNA After infection, produce a DNA copy of their RNA After infection, produce a DNA copy of their RNA DNA is inserted into host DNA DNA is inserted into host DNA Can be dormant for unlimited amount of time Can be dormant for unlimited amount of time Includes some cancers and HIV Includes some cancers and HIV

17. Viruses are NOT alive Viruses must infect another cell in order to reproduce Viruses must infect another cell in order to reproduce Use host’s respiration, nutrition, and other functions Use host’s respiration, nutrition, and other functions Are parasites Are parasites

18. Diseases Pathogens-disease causing agents Pathogens-disease causing agents Disease – conflict between the pathogen and the host; results when infection causes harm to the host; interferes with the host’s ability to obtain nutrients and energy needed to function properly Disease – conflict between the pathogen and the host; results when infection causes harm to the host; interferes with the host’s ability to obtain nutrients and energy needed to function properly

19. Bacterial disease in humans First discovered by Louis Pasteur First discovered by Louis Pasteur Some bacteria damage cells and tissues directly Some bacteria damage cells and tissues directly Some bacteria release toxins that travel through the blood then damage tissues Some bacteria release toxins that travel through the blood then damage tissues

20. Preventing bacterial disease Vaccines-preparation of weakened or killed pathogens that is injected into the body to stimulate the immune system Vaccines-preparation of weakened or killed pathogens that is injected into the body to stimulate the immune system Antibiotics-compounds that block the growth and reproduction of bacteria Antibiotics-compounds that block the growth and reproduction of bacteria

21. Controlling bacteria Sterilization by heat-destroys most bacteria since most cannot survive at high temperatures Sterilization by heat-destroys most bacteria since most cannot survive at high temperatures Disinfectants- chemicals used to kill bacteria Disinfectants- chemicals used to kill bacteria Food preparation and storage-canning or using preservatives such as salt, sugar, pickling Food preparation and storage-canning or using preservatives such as salt, sugar, pickling

22. Antibacterials Added to most soaps and cleaning agents Added to most soaps and cleaning agents Becoming problematic Becoming problematic Allowing many bacteria to become resistant to antibacterial agents Allowing many bacteria to become resistant to antibacterial agents Makes bacteria harder to kill with medications Makes bacteria harder to kill with medications

23. Viral disease Disrupt normal equilibrium in the cells Disrupt normal equilibrium in the cells Specific to species they infect Specific to species they infect Only be prevented with vaccines before infection Only be prevented with vaccines before infection

24. Viroids Single-stranded RNA molecules with no capsid Single-stranded RNA molecules with no capsid Enter cell and direct synthesis of new viroids Enter cell and direct synthesis of new viroids Infect plants and disrupt metabolism, stunt growth Infect plants and disrupt metabolism, stunt growth

25. Prions Protein-infectious particles Protein-infectious particles Cause disease by forming protein clumps which induce normal proteins to become prions Cause disease by forming protein clumps which induce normal proteins to become prions Damage nerve tissue and cells Damage nerve tissue and cells Mad-cow disease; Creutzfeldt-Jakob in humans Mad-cow disease; Creutzfeldt-Jakob in humans