Download Viruses-19.2

Bacteria and Viruses (19)
Name:
Viruses-19.2
General Characteristics
o Sub Microscopic “____________________________”
o Can not ___________________
o Obligate intracellular parasite (totally dependent on _______________ for
replication
o __________________ by antibiotics
o Made of a core of ______ or ________ surrounded by a protein coat
*Explain below why scientists have a difficult time categorizing viruses as living or
non-living:
Basic Structures of a Virus
1. Capsid:
2. Envelope: Similar to a ____________. ____________ the capsid.
3. Nucleic Acid:
-Retrovirus:
Ex: HIV
Shape of a Virus
Draw Here
1. _____________: Capsid has _____triangular faces and ______ corners
EX:
Draw Here
2. _____________: Capsid is a coiled ___________
EX:
3. ________________: Virus that infects bacteria
- Structure is unique: ____________ head on a _____________ tail
with DNA inside the head
Draw Here
Viral Roles
1. Harmful
-Virulent=_____________________
-Temperate=___________________
-Viruses can also play a role in causing ________________
ex: Cervical Cancer
2. Helpful
-Temperate virus can be used to cause ___________ _____________ within a
host population
ex: Tulips
-Can be used to introduce __________ into defective DNA
-“ biologic _________”
-used in genetic engineering
Viral Infection
1. LYTIC INFECTION
A. Virus injects _______ into host cell and forms a circle
B. Host cell begins making viral ________.
C. Assembles new ___________.
D. Lyses (___________) the cell ______________ new viruses.
Ex: T4 Bacteriophage
2. LYSOGENIC INFECTION
A. Virus ____________ DNA into host cell.
B. DNA forms a prophage. (embeds itself into the hosts _________)
C. Remains __________ for a period of time until ___________ factors activate it
into the lytic cycle. ( Chemicals, ____________, ______________, stress,etc)
D. Goes directly into the __________ cycle.
Ex: Herpes Simplex Virus, HIV
*Give 2 examples of viruses for plants, animals, and humans below: