VIRUS NOTES
SECTION 20.1 IN TEXTBOOK

KEY PLAYERS
o

Russian biologist in the 1890’s

Noticed tobacco plants were diseased but only knew it was because of something in the liquid
secreted by the diseased plant. Called the disease: ____________________________________
_________________________.
o

Dutch biologist in the 1890’s

Suggested that tiny particles in the liquid were causing the disease. Named the particles
“_____________________________” after the Latin word for ____________________________
o

American biochemist in the 1930’s

Isolated crystals of the “Tobacco Mosaic Virus”

This is important because living things ________________________________________
which means viruses are not truly ___________________________________________.

WHAT IS A VIRUS THEN?
o
A virus is a ____________________________________________________________________________
_____________________________________________________________________________________
o

They can only reproduce by ______________________________________________________________
STRUCTURE AND COMPOSITION
o
The way viruses look varies greatly.
o
Most are so small they can only be seen under an electron microscope.
o
Have a ________________________________________ that surrounds them called a
____________________________.
o
Simple viruses have only a _____________________ while
_____________________________________________________________________________________
o
Proteins on the capsid help them to enter ________________________________________.
o
Most viruses only can infect a specific kind of cell

Example

________________________________________________________________________
---------------------------------------------------------------------------------------------------------------------------------------------------------------WHAT HAPPENS WHEN A VIRUS INFECTS A CELL?

LYTIC INFECTIONS

Virus enters _____________________________________________

Virus ___________________________________________________

Too many copies cause the cell to _________________________________________________________

The _________________________________________________________________________________
and the process happens over and over and over and over and over…..etc.

LYSOGENIC INFECTIONS

Do not happen as quickly as lytic infections
1. Virus enters _______________________________
2. Inserts a _______________________________________________________________________
3. Cell unknowingly copies the virus DNA when it copies its own DNA.
4. At some point the virus will _______________________________________________________,
create more viruses like in a lyic infection and _________________________________________
and this process will happen over and over and over and over and over…..etc.
A CLOSER LOOK AT TWO VIRUSES

The _________________________________________________________

A capsid enters a host cell usually in the hosts nose.

The host inhales the capsid/cell deeper into nasal cavity.

The cold virus is a lytic infection so it quickly copies itself and then when the cell bursts, more copies of
the virus go out and infect other cells.


Causes _______________ later in life

This is an infection called a ____________________________________________________
It is similar to a _________________________________________ meaning it takes a long time
for the virus to ______________________________________________________

The virus is transmitted through __________________________________________________________
_________________________________.
Characteristic
Structure
Reproduction
Genetic Code
Growth & Development
Obtain & Use Energy
Response to Environment
Change Over Time
Virus
Cell