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The Virus. Engage. Ebola: The Plague Fighters Pathogens – How are they transmitted. Explore. TMV – Tobacco Mosaic Virus Models of Viruses. What is a Virus?. Virus Latin for Poison Non-cellular particle with DNA or RNA 1 or 2 Protein Coats (Capsids)

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The Virus

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The virus

The Virus



  • Ebola: The Plague Fighters

  • Pathogens – How are they transmitted



  • TMV – Tobacco Mosaic Virus

  • Models of Viruses

What is a virus

What is a Virus?

  • Virus Latin for Poison

  • Non-cellular particle with

    • DNA or RNA

    • 1 or 2 Protein Coats (Capsids)

    • May have Viral Envelope - Phospholipids

  • DO NOT respire or grow

  • ONLY function in a living cell

  • NOT given Latin names like living organisms

    (rabies virus) (polio virus)

    (adenovirus=adenoid tissue)

Questions discussion


  • Do Viruses Respire?

  • What type of genetic material do viruses have?

  • Can they have both DNA and RNA?

How are they classified

How are they Classified?

  • Shape of their protein coat (capsid)

    • Important in infection

  • Type of nucleic acid they contain

    • DNA or RNA

    • NEVER Both

Reproduction cycles

Reproduction Cycles

How do viruses replicate

How do Viruses Replicate?

  • The lytic cycle:

    1- absorption/attachment

    2- injection/entry

    3- replication of viral parts

    4- assembly

    5- release by lysis

  • Results in death of host cell

  • Virulent virus (only lytic cycle)

Lets go through the steps of the lytic cycle together

Lets Go Through the Steps of the Lytic Cycle Together!!!

Lysogenic cycle

Lysogenic Cycle

  • First steps just like lytic!!

  • Does NOT destroy the host cell

  • Nucleic acid joins the cell’s DNA. Viral DNA becomes a part of hosts cell DNA


  • Could go on for years

  • Temperate virus (capable of using the lytic and lysogenic cycles)

  • i.e. HIV, cold sores, shingles

Lysogenic cycle1

Lysogenic Cycle

Lets go through the steps of the lysogenic cycle

Lets Go Through the Steps of the Lysogenic Cycle!!!

Both cycles together

Both Cycles Together

Types of viruses

Types of Viruses

  • Animal viruses: Rabies, Polio, Mumps, Chicken pox, Small pox, and Influenza.

  • Plant Viruses: Tobacco mosaic virus (TMV), Banana streak virus, Carrot thin leaf virus

  • Bacterial Virus: Bacteriophages ( T1, T2, T3, and T4.)

  • SPECIFIC in what type of cell and what type of organism they infect

    • Polio – human nerve cell

    • T4 – only certain strains of E. coli

Different types of viruses

Different Types of Viruses


  • Respiratory infections; colds



Influenza virus

Influenza Virus

  • Virus that causes the flu

Small pox

Small Pox

The virus




  • RNA viruses that contain reverse transcriptase

  • This enzyme allows RNA to produce DNA

  • HIV is an example of the virus

Questions discussion1


  • What some differences between the lytic and lysogenic cycle?

  • What type of virus is HIV?

  • How is HIV one of the most successful viruses in reproducing?

Viruses living or not

Viruses: Living or Not?



  • Lytic and Lysogenic Manipulative

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