Viruses Are they alive ?

What is a Virus? A non – living, infectious particle made only of a strand of DNA or RNA surrounded by a protein coat. This protein coat is known as a capsid. Why would some scientists debate that a virus was living?

Why are viruses considered non-living? Viruses can not reproduce on their own. A host cell is needed for a virus to reproduce and make proteins.

A virus is referred to as a pathogen. A pathogen is any organism or nonliving particle that can cause an infectious disease. Viroids and prions are pathogens as well.

and use your book !! Define: 1)Viroid: 2)Prion:

Mad Cow Disease 1) What is mad cow disease? 2) What is the medical name for mad cow disease? 3) What is the human form of mad cow disease? 4) How can humans get vCJD? 5) How is the United States preventing the spread of vCJD? 6) What is one theory of how mad cow disease is caused? 7) How are healthy cows infected by cows with the disease? 8) When was the first case of vCJD reported? 9) How did the United States avoid spreading vCJD in December 2003? 10) List the symptoms of vCJD. 11) How is a case of vCJD confirmed? 12) Since there is no cure for vCJD, how are patients treated?

Mad Cow Disease News Clip VgB9sg5dy8w

The Structure of a Virus Surrounded by a protein coat called the capsid. Capsids have many different shapes. Each type of virus can infect only certain hosts. For example, a bacteriophage is a virus that only infects bacteria. The virus uses its capsid to attach to the host cell, like a key fitting a lock. There are 3 viral structures: bacteriophage, tobacco mossaic, and influenza.

How do Viruses make us sick? Viruses cause 2 types of infections. Use your book and write the analogies used to describe each. Refer to pg 549

2 Types of Viral Infection Lytic Infection Lysogenic Infection An infection pathway in which the host cell bursts releasing the new viral offspring into the host’s system. This infection does not take long for symptoms to occur. Example: Cold Virus & Flu The virus combines its DNA into the host cell’s DNA forming a prophage. This infection can lie dormant for a period of time before symptons occur. Example: AIDS, Herpes, Chicken Pox When a host’s cell bursts, the term used is Lyse.

Cell Lyse lyse Animated BIO