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CHAPTER 19

CHAPTER 19. BACTERIA AND VIRUSES. 19.1 Bacteria. I. Prokaryotes – single-celled organisms that lack a nucleus . Prokaryotes are commonly called bacteria . structures of bacteria: cytoplasm, cell membrane, cell wall, DNA/RNA, ribosomes , flagella

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CHAPTER 19

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  1. CHAPTER 19 BACTERIA AND VIRUSES

  2. 19.1 Bacteria I. Prokaryotes – single-celled organisms that lack a nucleus. • Prokaryotes are commonly called bacteria. structures of bacteria: cytoplasm, cell membrane, cell wall, DNA/RNA, ribosomes, flagella B. They cover nearly every square centimeter of Earth.

  3. Bacteria in moist environments have whiplike tails called flagella that help them move.

  4. 19.1 Bacteria C. Eubacteria- Larger of the two kingdoms of prokaryotes. 1. They live almost everywhere. 2. Most have a cell wall that give it shape and protect from injury. 3. The cell wall contains peptidoglycan.

  5. Ribosome Cell wall Cell membrane Peptidoglycan Pili Flagellum DNA The Structure of a Eubacterium

  6. 19.1 Bacteria D. Archaebacteria- Look similar to eubacteria but are chemically different. 1. Archaebacteria lack the peptidoglycanof eubacteria and also have different membrane lipids.

  7. 19.1 Bacteria 2. Live in extremely harsh environments. EX: oxygen-freeenvironments, extremely salty environments, hot springs.

  8. Eubacteria Archaebacteria Living in soil Infecting large organisms Thick mud Animal digestive tracts Salty lakes Hot springs Concept Map Section 19-1 Bacteria are classified into the kingdoms of include a variety of lifestyles such as live in harsh environments such as

  9. 19.1 Bacteria III. Identifying Prokaryotes A. Prokaryotes are identified by characteristics such as shape, the chemical nature of their cell walls, the way they move, and the way they obtain energy. 1. Shapes: Rod shaped = bacilli, spherical = cocci, spiral = spirilla.

  10. Rod-shaped bacteria (bacilli) Some types of these bacteria also have whiplike structures called flagella to help them move around. Escherichia coli or E.coli(found in the intestines of mammals)Salmonella typhi(causes typhoid fever and food poisoning) Bacilli

  11. Sphere-shaped bacteria (cocci) Streptococcus(strep throat)Staphylococci (responsible for "staph" infections and gangrene) Streptococcus(strep throat)Staphylococci (responsible for "staph" infections and gangrene) Cocci

  12. Spiral-shaped bacteria (spirilla)can use their shape to propel themselves by twisting like a corkscrew. Treponema pallidumcholera(syphilis)Borreliaburgdorferi (Lyme disease) Spirilla

  13. Streptococcus Streptococcus: chains of nearly spherical bacteria.

  14. Streptobacillus Streptobacillus: chains of rod-shaped bacteria.

  15. Staphylococcus Staphylococcus : spherical bacterium occurring in grape-like clusters.

  16. 19.1 Bacteria 2. Cell Walls: Gram-positive bacteria have thick cell walls and stain violet. Gram-negative have thinner walls outside the lipid layer and stain pink or light red. 3. Movement: you can also classify prokaryotes by whether they move and how they move. Ex. Flagella, snake or spiral forward, glide on slime.

  17. 19.1 Bacteria IV. Metabolic Diversity – how prokaryotes obtain their energy. • Heterotrophs or autotrophs- Some bacteria eat other organisms for energy while some can make their own food using light (photosynthesis) or chemicals (chemosynthesis).

  18. 19.1 Bacteria B. Releasing energy – energy is released by cellular respirationor fermentation or both. • Aerobic – bacteria that requireoxygento survive • Anaerobic – bacteria that can live with or without oxygen

  19. 19.1 Bacteria V. Growth and Reproduction A. Binary fission: bacteria grow until it has doubled in size, then it replicates its DNA and divides in half. • Conjugation: one bacterium uses a pilus to connect to another bacterial cell and exchange DNA. This allows for exchange of genetic information and increases genetic diversity.

  20. Conjugation

  21. Binary Fission

  22. 19.1 Bacteria C. Spore Formation: When conditions become unfavorable some bacteria form spores. Spores can remain dormant while waiting for more favorable conditions. 1. endospore – formed when a bacteria produces a thick internal wall that encloses its DNA and a portion of its cytoplasm.

  23. Endospore

  24. 19.1 Bacteria VI. Importance of Bacteria • Bacteria are vital to maintaining the living world. 1. Producers that capture energy by photosynthesis. 2. Decomposers – bacteria help ecosystems recycle nutrients by breaking down dead organic matter.

  25. 19.1 Bacteria • Nitrogen fixers– bacteria can convert nitrogen gas into ammonia; a form that can be used by plants. 3 ½. Denitrification – bacteria convert nitrates in soil into nitrogen gas for the atmosphere 4. Some bacteria produce chemicals called antibiotics that limit the growth of other bacteria. This helps keep us healthy.

  26. 5. Human uses a. Bacteria is used to produce a wide variety of foods,beverages, and medicines. b. Our intestines are inhabited by a large number of bacteria including E. coli. The bacteria produce vitamins for us and we provide a home and food for the bacteria.

  27. 19.3 Diseases Caused by Bacteria A. All bacteria require nutrients and energy; however disease results when bacteria interfere with the host’s ability to obtain enough nutrients to function properly.

  28. 19.3 Diseases Caused by Bacteria I. Bacterial Diseases in Humans A. The growth of pathogenic bacteria disrupts the body’s equilibrium by interfering with its normal activities and producing disease.

  29. 19.3 Diseases Caused by Bacteria and Viruses B. Louis Pasteur developed pasteurization – a process that is used to kill most harmful bacteria during food processing. C. Bacteria produce in one of two general ways: 1. Some bacteria damage the cells and tissues of the infected organism directly by breaking down the cells for food. Ex. Tuberculosis damages lung cells

  30. 19.3 Diseases Caused by Bacteria and Viruses 2. Other bacteria release toxins (poisons)that travel through the body interfering with the normal activity of the host. Ex. Streptococcus release toxins that can cause scarlet fever; botulism is a type of food poisoning that results from toxins

  31. 19.3 Diseases Caused by Bacteria D. Preventing Bacterial Diseases 1. A vaccine is a preparation of weakened or killed pathogens. A vaccine prompts the body to produce immunity to the disease. 2. Antibiotics are compounds that block the growth and reproduction of bacteria. Used to attack the cell walls of bacteria.

  32. Common Diseases Caused by Bacteria Section 19-3 Prevention Disease Pathogen Streptococcus mutans Borreliaburgdorferi Clostridium tetani Mycobacterium tuberculosis Salmonella enteritidis Streptococcus pneumoniae Vibriocholerae Regular dental hygiene Prevent tick bites Tetanus vaccination Vaccination Proper food-handling Maintaining good health Clean water supplies Tooth decay Lyme disease Tetanus Tuberculosis Salmonella food poisoning Pneumonia Cholera

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