What is a Virus???

Viruses

#1: Viruses possess genetic material (DNA or RNA)

#2: Viruses cannot survive without a host A host is where it lives (other organisms). If it is not in a host, the virus will die.

#3: Viruses are not considered to be cells

Virus Bacteria Fungus

Structure of a virus

How big is a Virus?

Diversity of Viral Structure RodCircularPolyhedral Bacteriophage

Viral Life Cycle: Lytic Summary: viral DNA  mRNA  Protein Virus will use the host cell to make proteins needed to create more viruses.

a. Virus approaches a specific cell to infect b. Virus attaches to the host cell Host Cell Virus c. Virus injects its DNA into the host cell d. Host cells organelles start “reading” the viral DNA. It has the recipe to destroy the host cell DNA and how to make more viral parts e. Viral assembly. All the created viral parts come together to form new viruses f. The host cell is destroyed or “lysed”. New viruses set out to find new cells to repeat the process

Lytic cycle Animation

The Lytic Cycle occurs…………. FAST!!!!!

Example: Influenza Transmission: Air

Example: Chicken Pox Occurs through direct contact with someone infected with the chickenpox virus, or through the air from an infected person's coughing or sneezing

Viral Life Cycle: Lysogenic viral DNA  becomes apart of host cell DNA  pops out of host cell DNA due to stress  mRNA  Protein Viral DNA becomes apart of host cell DNA; When stressed viral DNA will detach itself from host cell DNA and switch to the Lytic cycle

a. Virus approaches a specific cell to infect b. Virus attaches to the host cell and injects its DNA into the host cell Host Cell Virus c. Viral DNA approaches the host cell DNA d. Viral DNA becomes apart of the host cell DNA e. The viral DNA and host cell DNA is copied every time a new cell is created. f. Stress causes the viral DNA to pop out of the host cell DNA. The lytic cycle begins: more viral parts are created, assembled, and then the host cell is destroyed Viral DNA

Lysogenic cycle Animation The Lysogenic Cycle occurs.... SLOW!!!!

Example: Shingles The chickenpox virus remains dormant (not used) for years. Environmental pressure or extreme stress can cause the virus to switch in to the lytic cycle. Raise your hand if you have had chicken pox??? Raise your hand if you think you could you get it again??? Yes….you could get SHINGLES.

Example: Herpes Simplex Transmission: Coming into contact with someone who is infected with the virus. This could include kissing and sex. There is no cure.

Type 1 HSV: Oral Herpes – causes cold sores and sometimes genital herpes. Type 1 Herpes virus infects more than half of the U.S. population by the time they reach their 20s Two types of Herpes Simplex Virus Type 2 HSV: Genital Herpes