1. Viruses

2. Are composed of a core of DNA or RNA surrounded by a ______________.
Viruses
Viruses
Are ___________
Can NOT reproduce by themselves, but replicate with the help of a _______
Are composed of a core of DNA or RNA surrounded by a ______________.
NOT CELLS
HOST
PROTEIN COAT

3. Yes No Yes No Yes Yes Yes Characteristic of life
CELL
VIRUS
Contain specialized organelles
Obtain & use energy
Reproduce
Contain RNA or DNA
Yes No
Yes No
Only inside a living cell (host)
Yes
Yes
Yes

4. NO!
So, are viruses alive?
But viruses can cause disease in _______ kind of living organism—animals, ______, fungi, protists, and bacteria.
Ex. A _______________ is a virus that infects bacteria.
EVERY
PLANTS
BACTERIOPHAGE

5. Structure of a Virus ___________ (outer part of the protein coat)
________(inner part of the protein coat)
_____________
(either DNA or RNA)
ENVELOPE
ENVELOPE
CAPSID
NUCLEIC ACID
NUCLEIC
ACID
CAPSID

6. How are viruses identified?
A virus is often identified by which type of _______ it has.
Ex:_________, plant, or
___________ virus
They can also be identified by:
- ______
- Type of nucleic acid
- Structure of the capsid
HOST
ANIMAL
BACTERIAL
SHAPE

7. Helical
Binal
Polyhedral

8. TWO METHODS OF VIRAL REPRODUCTION: Lytic Cycle & Lysogenic Cycle

9. Lytic Cycle (rapidly kills host cell)
Virus ________ its nucleic acid into a cell
Viral DNA or RNA __________ the host cell to make new viruses
The cell breaks apart – “______” – killing the host cell and __________ new viruses
Released viruses are now ready to _______ other host cells
INJECTS
INSTRUCTS
LYSES
RELEASING
INVADE

10. 1 2 3 4 5

11. Cell before infection…
…and after.
Cell before infection…

12. Lysogenic Cycle The virus does _____ ______________ kill a host cell.
The injected viral DNA ______________ into the host chromosome and remains _____________ for a period of time (sometimes years).
It becomes ___________ later when it enters the lytic cycle.
NOT
IMMEDIATELY
INTEGRATES
HARMLESS
HARMFUL

14. Diseases Caused by Viruses
Effect on Body
Transmission
_________________
Sneezing, sore throat, fever
Contact with contaminated objects; droplet inhalation
Body aches, fever, congestion, fatigue
Noncancerous growths on the skin
Contact with warts
Helper T cells (immune system) destroyed
Contact with contaminated blood or body fluids
Fever, red itchy rash
Contact with rash; droplet inhalation
COMMON COLD
INFLUENZA
(FLU)
WARTS
AIDS
CHICKEN POX

16. WARTS
CHICKEN POX

18. Viruses are Specific to their Hosts
They can only attack __________cells
Not all viruses can pass between different___________(though some can).
Ex. _________ can be passed from animal to human.
SPECIFIC
SPECIES
RABIES

19. Viruses are Specific to their Hosts
COLD
The common _________ is a virus that specifically attacks _________ of the respiratory tract causing coughing, sneezing and sniffling.
Other viruses __________ other types of cells.
HIV virus specifically attacks
__________ cells of the
__________ system.
CELLS
ATTACK
T4 HELPER
IMMUNE

20. PREVENTION & VACCINATION
Viruses usually cannot be _______ with medicine, but many viral diseases can be _____________ by
Practicing good ____________
Making good ____________
Getting __________________
KILLED
PREVENTED
HYGEINE
CHOICES
VACCINATED

21. Vaccination:
Injecting a person with a ______________ or inactivated version of the virus. This stimulates the __________ system to ___________ the virus if it ever enters the body again.
Remember, antibiotics kill ONLY ______________.
WEAKENED
IMMUNE
ATTACK
BACTERIA

22. Q: What kingdom of life are viruses in? A: None! They are not alive.