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Viruses
A person that
studies viruses!!
http://www.cellsalive.com/howbig.htm
Electron Microscope
Characteristics
• Noncellular
• Contains a protein coat called the
capsid
• Have a nucleic acid core
containing DNA or RNA
• Capable of reproducing only when
inside a HOST cell
What are Viruses?
Core of DNA OR
RNA surrounded
by a capsid
(protein coat)
Are they living or nonliving?
LIVING
NONLIVING
•Contain DNA/RNA
•Does not reproduce
•DNA Replicates
Alone, Needs a
HOST in order to
survive
•Made of lipids,
proteins, nucleic
acids
•Undergo mutations
•Does not grow
•Are not made of
cells
Viral Structure
Bacteriophage
What are the parts of the virus?
Head
Capsid
DNA/RNA
Tail
Tail fibers
Viral Replication
(Lytic and Lysogenic Cycles)
What are the life cycles of the virus?
http://www.cat.cc.md.us/courses/bio141/lecguide/unit2/viruses/lytsum.html
A Virus attaches to the host and injects its
DNA into the cell.
B The DNA replicates in the host cell.
C The parts of the virus are created.
D The new viruses erupt from the host cell
(cell lyses (burst))
A Virus attaches to the host and injects its
DNA into the cell.
B The viral DNA attaches to the host DNA.
C DNA replication takes place (Interphase)
D The cell undergoes mitosis
E Stress causes the viral DNA to create the
“weird” protein thus creating an outbreak!
Lytic vs. Lysogenic
• Mysterious Invaders - A Closer
Look at Viruses
Types of Viruses
Bacterial
Plant
Animal
Bacterial Virus
• Viruses that attack bacteria are
called bacteriophage or just phage
Plant Virus
Tobacco Mosaic Virus
Animal Viruses
Herpes Virus
SIMPLEX I and II
Adenovirus
COMMON COLD
Influenza Virus
Chickenpox Virus
Papillomavirus –
Warts!
Retroviruses
Characteristics of
Retroviruses
• Contain RNA, not DNA
• Contain enzyme called
Reverse Transcriptase
• When a retrovirus infects a
cell, it injects its RNA and
reverse transcriptase enzyme
into the cytoplasm of that
cell
Retroviruses
• The enzyme reverse
transcriptase (or
RTase), which causes
synthesis of a
complementary DNA
molecule using virus
RNA as a template
Retroviruses
• HIV, the
AIDS virus, is
a retrovirus
• Feline
Leukemia Virus
is also a
retrovirus
What is a vaccine?
•It is a weakened virus or the virus
without its RNA/DNA.
•It causes the body to react and
defend.