1. Bacteria and Viruses Chapter 19

2. Bacteria Bacterial cells do not have nuclei so they are Prokaryotic. Bacteria used to be collectively grouped into the Kingdom Monera but now it is separated into 2 Kingdoms: Eubacteria and Archaebacteria.

3. Eubacteria Common bacteria, wide variety of organisms that live almost everywhere Some can cause disease Eubacteria have a cell wall that contains a carbohydrate called peptidoglycan.

4. Archaebacteria Ancient bacteria that live in very harsh environments. Have cell walls that lack peptidoglycan. In fact their DNA is more like that of a eukaryote than a eubacteria’s. This is why many people believe that archaebacteria are the early ancestors of eukaryotes.

5. Structure Bacteria do not have a nucleus. Bacteria tend to be smaller than eukaryotic cells. Bacteria are single-celled organisms but sometimes they stick together and live in colonies.

6. Structure Bacteria have a single circular strand of DNA. Bacteria reproduce by binary fission, which is basically when the cell pinches in half. Some bacteria have flagella that help to propel them.

8. Shape Bacilli –rod shaped Cocci—spherical shaped Spirilla—spiral shaped

10. Cocci Bacteria Cocci bacteria can group together to form: –Chains—streptococci –Clusters—staphylococcus

11. Obtaining Energy Bacteria can be either autotrophs or heterotrophs.

12. Obtaining Energy Bacteria can be either autotrophs or heterotrophs. –Autotrophs—make their own energy photoautotroph –perform photosynthesis like plants (cyanobacteria) Chemoautotroph-obtain energy from inorganic materials like sulfur and ammonia –Heterotrophs—must obtain energy from another source

13. Releasing Energy Bacteria can release energy through cellular respiration (requires Oxygen) or fermentation (does not require Oxygen) –Obligate Aerobes—require Oxygen –Obligate Anaerobes—require Oxygen- free conditions –Facultative Anaerobes—do not require Oxygen but can survive in its presence

14. Reproduction Bacteria can reproduce at an incredible rate. Some will divide in as little as 20 minutes. If there were unlimited resources, bacteria could reproduce to equal 4000 times the mass of the Earth in 48 hours. Binary fission (assexual)

15. Endospore Some bacteria like anthrax form spores that allow them to remain dormant for months, years, even centuries. This allows them to survive through extreme heat or total lack of nutrients.

16. Bacteria in Nature Bacteria can be useful. Many help to capture energy from the sun others breakdown dead or decaying material so that the nutrients and materials can be recycled into a form that other organisms can use.

17. Human Uses Food processing Digest oil spills Synthesize drugs and chemicals

18. Bacteria and Disease Bacteria cause disease in 2 ways: –Destroy the hosts tissues (Tb) –Release toxins that poison the host (C. botulism) See chart p. 486/489

19. Antibiotics Antibiotics are used to block the growth and reproduction of bacteria. Why are some bacteria drug resistant?

20. Controlling Bacteria Sterilization—is the process of destroying the bacteria on a nonliving surface by extreme heat or chemicals. What is the difference between an antiseptic and a disinfectant?

21. STOP

22. Viruses Viruses are particles of nucleic acid (either DNA or RNA) surrounded by a protein coat (called a capsid). Viruses vary in size and structure. Viruses can only replicate by entering a host cell and using that cell’s materials to copy itself.

23. Viral Infection When a virus enters a cell it will begin one of 2 cycles: p 481 –Lytic Cycle—virus enters a cell, copies itself, and bursts the cell –Lysogenic Cycle—virus enters a cell, embeds its DNA into the cell’s DNA so that it is replicated along with the host cell, eventually this virus will wake up and begin destroying the cells.

24. HIV Human Immunodeficiency Virus—The virus that causes AIDS HIV attaches to and enters macrophages ( a type of white blood cell). It then uses an enzyme called reverse transcriptase to change its RNA into DNA. This process causes many mistakes (mutations). This is why HIV mutates or changes so easily. This new DNA is embedded in the host cell’s DNA. When the virus replicates it does not burst the cell, instead the new viruses are released by budding. A person with HIV usually shows no symptoms of the disease for at least 8-10 years.

25. HIV Eventually the HIV virus begins to invade T cells. When the virus replicates in the T cells it burst and destroys them. It is the low number of T cells that leave the body unable to protect itself against infection thus the onset of AIDS.

26. http://learn.genetics.utah.edu/content/begin/cells/scale/

27. Emerging Viruses 1. West Nile 2. Avian Flu 3. Hanta Virus

28. Prions Prions are disease-causing proteins with no nucleic acid. These proteins are folded into shapes that prevent them from working. Contact with a prion will cause a protein in your body to become folded incorrectly and not function. Mad Cow disease or Creutzfeldt- Jakob Disease is caused by prions. Prions cannot be destroyed by cooking

29. Bacteria… Single Cell Organism This type of infection is treated with antibiotics Can be harmful or beneficial to humans Capable of multiplying by themselves Meningitis Pneumonia Strep Throat Staph Infection All of these photos are of different types of bacteria. Many bacteria have cilia and/or flagellum for locomotion. These are single celled organisms Rigid Cell Wall

30. Viruses… Viruses are not considered living organisms because they do not have the ability to reproduce on their own. They must have a host cell to reproduce. Viruses are very simple and contain either DNA or RNA. Non-living Has a protein coat Must have a host to reproduce HIV Flu Chicken Pox Common Cold

31. Viruses differ from bacteria in that all viruses — A cause insect-borne diseases B can be destroyed by antibiotics C have rigid cell walls D must be reproduced in living cells

32. D

33. Which of the following is found in both cells and viruses? A Silica B Genetic material C Digestive cavity D Flagella

34. B

35. Some antibiotics cause patients to exhibit digestive side effects. These side effects are most often the result of — A bacteria being killed in the digestive tract B the antibiotics being converted into stomach acids C too much water being drawn into the digestive tract Dthe stomach wall being torn

36. A

37. Which of the following explains why antibiotics can treat flu-like symptoms caused by bacteria but are ineffective against flu? A Flu is a response to an antigen. B Antibiotics require time to work. C Antibiotics strengthen antibodies. D Flu is caused by a virus.

38. D

39. Lactose is a naturally occurring sugar found in milk. Some dairy products, such as yogurt, may contain live bacteria. These products are useful to people who lack the ability to digest lactose. What does this information demonstrate? A Bacteria raise the acidity of processed foods. B Some bacteria interfere with digestion. C Bacteria can prevent insulin production. DSome bacteria are beneficial to human health.

40. D