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Viruses
Biology 11
Viruses
• Virus = Latin word for Poison
• Viruses have both living and non-living
qualities
• Unlike all true organisms (even the most
simple bacteria) viruses have no cellular
structure
– No cell membrane
– No organelles (including ribosomes)
Assignment Discovery - Viruses
Viruses
• Viruses do not require energy – or
carry out other common life
processes such as growth,
respiration and metabolism
But…
• They can reproduce with a host
cell
Basic Structure
• Very small - measured in
nanometers (nm)
• Two main parts:
– Protein coat (a.k.a. capsid)
– Core (contains DNA or RNA)
Shapes of Viruses
• Many different shapes:
– Spherical
– Rodlike
– Cubical
– “moon-lander”
Rotavirus
Tobacco Mosaic Virus
H.I.V.
Marburg Virus
Bacteriophage –
a virus that infects bacteria
Lytic Cycle – see page 337
VIDEO
• Understanding Viruses
• Questions
Dengue Fever
• Life Cycle of a Virus
Video
Viral Replication
Phage Photo Gallery
Phage attaching to host
More on virus shape / structure…
Influenza of 1918
• Nova Science Now
• Q: What does AZT do for people with HIV?
• A: Inhibits the life cycle of HIV
– AZT or azidothymidine is a nucleoside
analog reverse transcriptase inhibitor (NRTI)
– Blocks reverse transcription
– HHMI Animation
Q: How did chicken pox get its name?
A: Not completely sure why…
Theories include:
1. French word ‘ciche’ means chickpea, related to
the size of the pock
2. Old English word ‘gican’, which means itch
FYI:
•A.k.a. Varicella zoster virus (VZV)
•One of eight strains of herpes virus
•Can develop into shingles later in life
Test Review Jeopardy
• Virus attacks prostate cancer!
Getting to know VIRUSES!!!
• Getting to know viruses
• Profile: West Nile Virus
• Viruses in the News:
Using Viruses to kill bacteria?
• Case Study
Section I: #5
• Were the methods and procedures used
by the Europeans in this historical
experiment overly scientific? Why or
why not?
CASE STUDY