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“Simple” Organisms

“Simple” Organisms. Is a virus a living thing?. Viruses , although not technically living due to the lack of cellular structure, are classified as microorganisms. Viruses- Not living. Reproduction- only with a host cell Genetic code- DNA or RNA Growth/ development- NO

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“Simple” Organisms

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  1. “Simple” Organisms

  2. Is a virus a living thing? • Viruses, although not technically living due to the lack of cellular structure, are classified as microorganisms.

  3. Viruses- Not living Reproduction- only with a host cell Genetic code- DNA or RNA Growth/ development- NO Obtain and use energy- NO Response to environment- NO Change overtime- Yes Asexual or sexual DNA Yes Yes Yes Virus Living Cell

  4. Virus- Latin= “poison” • Have nucleic acids, protein, and come have lipids • But they ARE NOT living • Core = RNA or DNA that is surrounded by protein coat • Will bind to a receptor on the host and infect their DNA into the host

  5. Is a virus a living thing? • Viruses are composed of a protein coat (called a capsid) that protects a nucleic acid - either DNA or RNA. • The shape of the capsid determines the type of cell the virus can infect.

  6. Is a virus a living thing? • A virus can only exist by infecting a host cell. • Viruses are classified by the reproductive cycle it uses to infect the host cell. Virus

  7. Fill It In … Name 2 reasons that viruses are not considered living things: 1. 2.

  8. Is a virus a living thing? • 1. The lytic cycle describes the “life cycle” in which a virus uses the host cell to make copies of itself, then quickly kills the host cell as new virus copies are released.

  9. https://www.youtube.com/watch?v=3DP-MAhr0YY Lytic Cycle • Make copies of itself and infect host cell • Cell cannot tell the difference between virus’ DNA and its own • Will transcribe and translate viral DNA • Viral DNA and protein will eventually chop and KILL the host cell • Only after hundred of copies of the virus was made

  10. Is a virus a living thing? • 2. The lysogenic cycle describes the “life cycle” in which the virus has a dormant stage in which the virus remains inactive within the cell. • This dormant period may last for weeks, months, or years. • An environmental trigger may cause the viral DNA to emerge from the host DNA and begin a lytic cycle of reproduction.

  11. Lysogenic • Will integrate itself into the host DNA • Will remain dormant for some time • It will eventually replicate itself along with the host DNA

  12. Fill It In … • Using the diagram, explain how lytic and lysogenic are different:

  13. How a virus works

  14. Is a virus a living thing? • Viruses are pathogenic, or disease-causing microorganisms

  15. Is a virus a living thing? • HIV causes AIDS. • HIV infects T-cells, which are important for the immune response. • Thus, people with AIDS often die of opportunistic infections, such as pneumonia.

  16. Is a virus a living thing? • Several different viruses cause influenza (the “flu”). • The influenza viruses mutate rapidly, meaning the actual virus being spread changes with each outbreak.

  17. Is a virus a living thing? • Flu epidemics are caused by viruses that are genetically different enough from earlier years’ viruses that people have little immunity to them.

  18. Is a virus a living thing? • Influenza viruses infect respiratory cells. • The lysis of these cells leads to some of the typical symptoms of the flu, such as sore throat and congestion.

  19. Is a virus a living thing? • A poxvirus causes smallpox. • Special efforts have eradicated the smallpox disease; however samples of the smallpox virus were kept for study and are currently stored at the CDC in Atlanta.

  20. Is a virus a living thing? • Smallpox starts in the cells of the lymph nodes and lungs, then moves into other internal organs and the skin. • Symptoms include severe headaches, muscle ache, and pustules on the skin.

  21. Virus Prevention and Treatment • Vaccines can be developed for viral diseases. A vaccine uses a dead or weakened form of the virus to “turn on” the immune response so that antibodies are produced.

  22. Virus Prevention and Treatment • Vaccines can be developed for viral diseases. A vaccine uses a dead or weakened form of the virus to “turn on” the immune response so that antibodies are produced.

  23. Virus Prevention and Treatment • Active immunity to a virus is conferred by a vaccine or by exposure to the virus itself. • Passive immunity is conferred when antibodies are passed between individuals (ie. through breast milk). • Antiviral medications work by interrupting the virus’s life cycle. Antibiotics are NOT effective against viruses!

  24. Vaccines • Resembles disease causing agent • Made from weakened or dead microbe • Stimulates immune system and creates memory cells

  25. Active immunity • Production of antibodies by an organism after an encounter • Natural- Due to infection • Artificial- Vaccination

  26. Passive Immunity • Acquisition if antibodies from another organism • Natural- pass from mother to child during placenta or breast milk • Artificial- Immune serum or antivenom

  27. Viruses and Natural Selection • Viruses often mutate rapidly, meaning the actual virus being spread changes with each outbreak.

  28. Viruses and Natural Selection • 2.Mutations in the HIV virus make developing a treatment or vaccine difficult. Viruses that are resistant due to mutations can survive and reproduce by natural selection. • 3.Flu epidemics are caused by viruses that are genetically different enough from earlier years’ viruses that people have little immunity to them.

  29. Fill It In … Identify 3 viral diseases: 1. 2. 3.

  30. Check Yourself! • What are the two parts of a virus? • What are the two reproductive cycles of viruses? • What is a pathogen? • What type of cell does HIV infect? • Why is there a different flu virus each year?

  31. Check Yourself! • What are the two parts of a virus? CAPSID (PROTEIN COAT) NUCLEIC ACID (DNA OR RNA)

  32. Check Yourself! • What are the two reproductive cycles of viruses? LYTIC CYCLE & LYSOGENIC CYCLE

  33. Check Yourself! • What is a pathogen? DISEASE-CAUSING MICROORGANISM

  34. Check Yourself! • What type of cell does HIV infect? T-CELLS

  35. Check Yourself! • Why is there a different flu virus each year? IT RAPIDLY MUTATES

  36. Are all bacteria “bad”? • All bacteria are classified in the kingdoms Eubacteria and Archeabacteria. • They are differentiated by the chemicals found in the bacterial cell wall. • They are all unicellular and prokaryotic.

  37. Bacteria Eubacteria Largest Kingdom Live Everywhere Have cell wall made of peptidoglycan Some have second membrane Spores Look similar and lack nuclei Have cell wall but NO peptidoglygan and have a different lipid DNA show relation to eukaryotes Live in VERY harsh environments HOT, Salty, No Oxygen Eubacteria Archaebacteria

  38. Cell wall • Gram staining • Gram Positive- has peptidoglycan cell wall • Will turn violet • Gram Negative- no peptioglycan cell wall • Will be a lighter color (pink)

  39. Are all bacteria “bad”? • Bacteria typically reproduce through binary fission, but can also exchange DNA in a process known as conjugation. • This allows for genetic variation in a bacterial population.

  40. Are all bacteria “bad”? • The vast majority of bacteria in our world are beneficial. • They are important decomposers and perform many other ecosystem services. • They exist in the intestines of some animals and aid digestion. • They are also important in food production.

  41. Are all bacteria “bad”? • Some bacteria are pathogenic. One example is the bacterium Mycobacterium tuberculosis, which causes tuberculosis. The disease attacks the lungs and causes coughing, chest pain, fatigue and fever – it can be fatal if not treated. This bacterium causes disease because it destroys cells. The cells are broken down by the bacteria as a source of nutrition. Other bacteria harm the host by releasing toxins such the bacterium that causes food poisoning.

  42. Are all bacteria “bad”? • Pathogenic bacteria can be treated with antibiotics. Antibiotics kill the bacteria by destroying the cell wall. Bacteria that are resistant to antibiotics can survive and reproduce by natural selection. This means that new antibiotics must continually be developed. Bacteria

  43. Fill It In … Identify 3 ways that bacteria are beneficial: 1. 2. 3.

  44. Importance to Humans • Decomposers- will break down dead organisms • Clean sewage • Eat dead tissue • Nitrogen fixation • Will take N2gas and make NH3 a compound plants and animals can use • Human use- • In stomach- help make vitamins (biotin and Vit K) • Digest petroleum • Clean water pollution

  45. Are all bacteria “bad”? • Some bacteria are pathogenic (cause disease). • One example is the bacterium Mycobacterium tuberculosis, which causes tuberculosis or TB.

  46. Are all bacteria “bad”? • The disease usually attacks the lungs and causes coughing, chest pain, fatigue and fever - it can be fatal if not treated. • This bacterium causes disease because it destroys cells. • The cells are broken down by the bacteria as a source of food/nutrition.

  47. Are all bacteria “bad”? • Other bacteria harm the host by releasing toxins such as the bacterium that causes food poisoning.

  48. Check Yourself! • Which two kingdoms include bacteria? • How do bacteria reproduce? • Name two ways that bacteria cause illness.

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