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Viruses, Viroids, and Prions
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Slide 1

Viruses, Viroids, and Prions

Viruses, Viroids, and Prions

Slide 2

Are Viruses Living or Non-living?

Are Viruses Living or Non-living?

Viruses are both and neither

They have some properties of life but not others

For example, viruses can be killed, even crystallized like table salt

However, they cant maintain a constant internal state (homeostasis).

Slide 3

What are Viruses?

What are Viruses?

A virus is a non-cellular particle made up of genetic material and protein that can invade living cells.

Slide 4

Viral History

Viral History

Slide 5

Discovery of Viruses

Discovery of Viruses

Beijerinck (1897) coined the Latin name virus meaning poison

He studied filtered plant juices & found they caused healthy plants to become sick

Slide 6

Tobacco Mosaic Virus

Tobacco Mosaic Virus

Wendell Stanley (1935) crystallized sap from sick tobacco plants

He discovered viruses were made of nucleic acid and protein

Slide 7

Smallpox

Smallpox

Edward Jenner (1796) developed a smallpox vaccine using milder cowpox viruses

Deadly viruses are said to be virulent

Smallpox has been eradicated in the world today

Slide 8

Viewing Viruses

Viewing Viruses

Viruses are smaller than the smallest cell

Measured in nanometers

Viruses couldnt be seen until the electron microscope was invented in the 20th century

Slide 9

Size of Viruses

Size of Viruses

Slide 10

Viral Structure

Viral Structure

Slide 11

Characteristics

Characteristics

Non living structures

Noncellular

Contain a protein coat called the capsid

Have a nucleic acid core containing DNA or RNA

Capable of reproducing only when inside a HOST cell

Slide 12

Characteristics

Characteristics

Some viruses are enclosed in an protective envelope

Some viruses may have spikes to help attach to the host cell

Most viruses infect only SPECIFIC host cells

CAPSID

ENVELOPE

DNA

SPIKES

Slide 13

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