Unit 5 Notes

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Unit 5 Notes

• Viruses

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Viruses Are They Alive?

• Characteristics of Life
• Made of Cells
• Respond to the environment
• Need energy
• Reproduce
• Grow Develop
• Adapt

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Viruses Are They Alive?

• Characteristics of Viruses
• Viruses ARE NOT made of Cells
• Viruses must reproduce in living Cells
• Viruses can only be seen using an Electron
  Microscope
• Viruses are made of a Nucleic Acid core and a
  Protein Coat

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Viruses Are They Alive?

• NO, VIRUSES ARE NOT LIVING ORGANISMS

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Viruses
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Structure of Viruses

• They have a simple structure
• A core of Nucleic Acid DNA or RNA, but not both
• A protein coat, called a capsid

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Structure of Viruses

• Some Viruses have an Envelope on the outside of
  the capsid
• It is made of phospholipids, proteins, and
  carbohydrates similar to the cell membrane
• It may have spikes for recognition and
  attachment

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Bacteriophage

• Only infects Bacteria
• Structure
• Capsid made of protein
• Tail- used to help find a cell to infect
• Nucleic Acid Found in the Head

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Viral Reproduction

• Lytic Cycle
• or
• Lysogenic Cycle

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Viral Reproduction

• Lytic Cycle
• Causes immediate cell death once the cell is
  infected by the virus T phage
• Click here to view

• Steps
• 1. Attachment
• 2. Entry
• 3. Viral Replication of Protein
• 4. Proteins Assemble
• 5. Cell Burst and Viruses are released

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Viral Reproduction

• Lysogenic Cycle
• Does not cause immediate death of the cell
• Click here to view

• Steps
• 1. Attachment
• 2. Entry
• 3. Provirus Formed
• 4. Cell divides with Provirus
• 5. Virus DNA separates from host DNA
• 6. Viral Replication
• 7. Viral Assembly
• 8. Cell Lysis

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Viral Reproduction
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Human Diseases

• Viruses that cause human disease include
• Herpes, Chicken Pox, AIDS
• Vaccinations can provide protection against some
  viruses
• Makes your body produce antibodies
• Small Pox was eliminated by vaccinations

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HIV

• HIV is a retrovirus it can make DNA from RNA
• Causes the disease AIDS
• Have a capsid, an RNA core, reverse
  transcriptase, and an envelope

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HIV

• Parts of a Retrovirus
• 1. Spikes used to attach to a cell
• 2. Capsid made of Protein
• 3. RNA Nucleic Acid found in the capsid
• 4. Reverse Transcriptase enzyme needed for DNA
  to from from RNA
• 5. Envelope make of phospholipids and proteins

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Other Diseases

• Viroids pure, small pieces of RNA that cause
  disease in plants
• Prion pieces of proteins that cause diseases in
  animals
• Mad Cow Disease first seen in cows in England

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Unit 5 Notes

• Viruses