This document discusses viruses and bacteria. It defines bacteria as unicellular prokaryotes that lack organelles like a nucleus. Viruses are described as non-living particles that need a host to reproduce and are smaller than bacteria. The document lists some common human viruses including hepatitis A, influenza, herpes, and HIV. It explains that antibiotics only work on bacteria, not viruses, and how the immune system develops immunity through memory cells, helper T cells, and killer T cells to fight diseases. Vaccination is highlighted as the best way to build immunity against viruses.

1. Viruses and
Bacteria
Summit Virtual Academy

2. Bacteria are Prokaryotes
• Unicellular
• Lack a membrane bound nucleus
• Lack most other organelles found
in eukaryotic cells
• Reproduce asexually by binary
fission

3. Bad Bacteria
• Any organism that
causes disease is called
a pathogen
• Salmonella typhii=
typhoid fever
• Streptococcus-strep
throat

4. What is a virus?
• Nonliving particle that causes disease
• Ex: Influenza, HIV, smallpox
• Need a host to reproduce
• Smaller than bacteria
• Bacteriophage- virus that infects bacteria

5. Structure of viruses.
• Viruses are composed of:
• Nucleic acids (DNA,RNA)
• Protein coat (capsid)

6. Types of Viruses

7. Human Viruses
Hepatitis A
Pneumonia
Influenza
Herpes
simplex
Hepatitis B
SARS

8. Viral Infections
• EX: herpes viruses, hepatitis viruses, AIDS is caused by a
retrovirus (HIV)- a virus that invades DNA.
• Antibiotics do not work on viruses, and their use for a
viral infection merely leads to antibiotic resistance!

9. HIV
• Human Immunodeficiency Virus
• Causes AIDS
• A retrovirus
• Contains only RNA
• Infects white blood cells
https://en.wikipedia.org/wiki/HIV/AIDS#/media/File:HIV-budding-
Color.jpg

10. Influenza
• Flu virus

11. Smallpox
• Deadly virus
• Infects only humans
• Destroyed in 1980

12. Side Note: Diseases in Humans
Viral vs. Bacterial

13. Why are viruses so
difficult to kill???

14. How does our body fight
Diseases?
• Pathogen enters body
• Immune cells fight it
• If they fail T cells become involved
• Two types:
• Helper T cells – interacts with B cells – B cells make
antibodies
• Some B cells don’t fight but remember the pathogen
(memory cells)- the next time the pathogen invades the cells
respond immediately – no symptoms result
• Killer T cells – release enzymes into the pathogen –
kills it

15. Immunity
• Passive- transferring antibodies from mother to baby
• Injecting antibodies – snake anti-venom
• Active- vaccines
• When the body builds immunity naturally – chicken pox

16. Vaccination
• Vaccines are weakened
or dead or versions of a
virus given to build
immunity to that virus
• Best protection against
viruses? Wash your
hands!