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Chapter 19-2 Notes

Chapter 19-2 Notes. Definition of viruses:. Non-living (?) disease-causing particles Composed of DNA or RNA surrounded by a protein coat. Can only reproduce when inside other living cells. . Structure of a virus. C apsid Made up of proteins (receptors)

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Chapter 19-2 Notes

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  1. Chapter 19-2 Notes

  2. Definition of viruses: • Non-living (?) disease-causing particles • Composed of DNA or RNA surrounded by a protein coat. • Can only reproduce wheninside other living cells.

  3. Structure of a virus Capsid • Made up of proteins (receptors) • Its purpose is to “trick” the cell into letting it inside the cell membrane. http://www.genetherapynet.com/viral-vectors.html (2:24 minutes, clip 3)

  4. Examples of structures Influenza virus Bacteriophage Tobacco Mosaic Virus

  5. Bacteriophage • A virus that infects a bacterium cell.

  6. Types of Viral Infection

  7. Lytic Infection • Both lytic and lysogenic infections begin with the virus attaching to the cell and injecting its DNA. • The viral DNA over-powers the cell’s DNA and causes the cell to make new viruses instead of doing its normal functions. • The new viruses release an enzyme to dissolve the cell membrane and exit the cell, free to infect new cells.

  8. Lysogenic Infection • Instead of immediately causing the cell to reproduce the viruses and bursting open the cell, the viral DNA (called a prophage) is inserted into the cell’s DNA. • Both pieces of DNA (the cell’s and the virus’s) are replicated when the cell reproduces for many generations. • The viral DNA is removed from the cell’s DNA and is free to begin lytic infection.

  9. Which type of infection is this?

  10. Importance of Viruses 3:23 minutes, Clip 6: Influenze vaccine If we have a vaccine to the flu, why do we need to get a new shot each year? 3:04 minutes, Clip 7: RNA viruses

  11. Retroviruses/RNA viruses • Viruses that contain RNA instead of DNA • Are not “checked” for mutations like DNA viruses are, so mutate often and quickly • Remain dormant for long periods of time • Examples: Flu, HIV

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