Do Now NB 144 top 8 minutes

• Expectations: – In seat at the bell, ready to go!– Notebook out!

• DO NOW: 1+ Paragraph– What did you learn about nutrition?– Are there any changes (big or small) that you

plan on making?

Happy Monday

• Agenda!– Notes on Viruses– Short video + Bill Nye Video– Did your group present to me?– How many days left until EOGS??

Viruses

Cornell Notes NB 145 & 147

Question | Details

What is a virus?

• The word VIRUS comes from the Latin word for “poison” or “slimy liquid”.

• A virus is a non-living particle that enters and then reproduces in a cell.

• It is:– Smaller than a cell– Not considered a living

organism– Is virulent—it can cause

disease

Where do viruses come from?

• Viruses may – Have de-evolved from

higher life forms– Have started out at the

same time as cells– Be escaped genetic

material (or extra parts of a chromosome)

• That means that perhaps your body can make its own viruses!

Viruses are not cells

• They do not use their own energy to grow or respond to their surroundings

• They cannot make food, take in food or produce waste

• They can multiply—but only when they are inside another living cell

• Viruses come in many shapes and sizes

Properties of a virus

• Viruses consist of DNA or RNA but never both

Diagram of a virus NB 146

• Viruses can be brick, cylindrical or oval in shape or they may have more complicated structures almost like robots

• Scientists can use the shape of a virus to identify it

(virus shapes, continued..)

Rabies Ebola

InfluenzaEarly Italian scientistsThought this illness was caused by the INFLUENCE of the starsAnd planets..

Hepatitis

Polio

Rhinovirus(common cold)

Rotavirus

Virus size

• Viruses vary in size• They are smaller than

cells• They cannot be seen

with our microscopes.• They are between 20

nm and 200 nm• (1 nm =

1/1,000,000,000th of a meter)

Virus names

• Viruses are named for– The disease they cause (polio virus)– The organisms they infect (tobacco mosaic

virus)– The place where they were found (West Nile

virus)– The scientist who discovered the virus

(Epstein-Barr virus—causes mononucleosis)

Rabies

Influenza

Smallpox

Edward Jenner

Polio

Dr. Jonas Salk 1914-1995

Parts of a Virus

• Viruses have two basic parts– A protein coat that

protects the virus– An inner core of

genetic material

• Viruses connect to cells with a “lock and key” method

How do viruses (most) attack cells and make us sick??

Let’s use the T4 bacteriophage as an example:

T4 bacteriophage is a virus that looks a lot like an alien landing pod------>

With its six legs, the bacteriophage attaches to the surface of the much larger bacteria Escherichia coli (E. coli).

Once attached, the bacteriophage injects DNA into the bacterium. The DNA instructs the bacterium to produce masses of new viruses. https://www.youtube.com/watch?v=Rpj0emEGShQ

So what happens to the bacterium?

So many new “baby” viruses are produced

that the E. coli BURSTS!!

This process of bursting is called LYSIS.

Active and Hidden viruses

• Both inject genetic materials into the host.

• Both burst open the cell after they multiple

• Both kill the host.

• Active viruses multiply immediately

• Hidden viruses hide and multiply later.

• Hidden viruses can stay inactive for years.

• Each time the cell divides, the virus’ genetic material is copied along with the host’s genetic material

Are any virus’ good?

• Viruses can cause disease.

• Viruses can be helpful.– Cow pox virus helps make people immune to

small pox