What is a Virus???

Viruses

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

#2: Viruses cannot survive without a hostA 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

#3: Viruses are not considered to be cells

Virus

Bacteria

Fungus

Structure of a virus

How big is a Virus?

Diversity of Viral Structure

Rod CircularPolyhedral Bacteriophage

Viral Life Cycle: LyticSummary: 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: Lysogenicviral 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