Viruses are non-living parasitic entities that can only reproduce by infecting a host cell. They contain either DNA or RNA surrounded by a protein coat and come in various shapes. Viruses infect a wide diversity of organisms like humans, causing diseases such as AIDS, chickenpox, and herpes. They spread through direct or indirect contact between hosts, through bodily fluids or contaminated surfaces. Vaccines help prevent the spread of viruses by exposing the immune system to weakened or dead forms of viruses.

1. Viruses
 A cellular
 No organelles
 Parasitic
 Must infect a host in order to
reproduce
 Infect a diversity of organisms
 Examples: AIDS, chicken pox,
herpes
 Do not have all characteristics of
life
 Can’t metabolize or grow
 Evolutionary pathway unclear

2. Morphology
 Viron: single virus particle
 Basic structure:
 Nucleic acid core (DNA or RNA)
 Capsid: Protein external covering
 4 main shapes
 Filaments
 Isometric
 Envelope
 Head and Tail

3. Genetic Information
 Can be DNA or RNA genome
 Genome is small
 DNA viruses: DNA directs host cell’s replication
 Make new copies of viral genome and then transcribe and
translate the viral proteins
 RNA viruses: RNA makes enzymes that can replicate RNA
into DNA

4. Ways a virus can
spread
1. Contact transmission
 Shaking hands, kissing
 Bodily fluids (saliva, breast milk)
2. Indirect contact
 Utensils, cups, bedding
3. Droplet spread
 Coughing, sneezing
If a virus spreads quickly it can become an epidemic

5. Virus Prevention
 Vaccine
 Builds immunity
 Prepared from live or dead virus
 Human childhood vaccines: polio,
mumps, measles, rubella, chicken
pox
 Live vaccines more effective
 Small chance it could mutate to
become infectious

6. Today’s Lab
 Virus transmission simulation
 Complete as a class
 Pretend to share bodily fluids
 Dolphin case study: Based on real life
 Significant increase in dolphin
strandings in 2013–2014
 Possibly due to cetacean morbillivirus
 To complete the lab
 Complete internet research
 Answer the questions in the word
document