1. Viruses

2. What is a Virus?
Viruses are tiny, non-cellular, infectious agents that invade living cells and take over their machinery to make copies of themselves.

3. Cannot reproduce on their own Are not made of cells
Viruses are NOT considered living based on the characteristics of life, because they:
*Do not make/use energy or have any metabolism (they have no organelles)
Cannot reproduce on their own
Are not made of cells
Do not grow/develop on their own

4. Are viruses living? no
Why? Be specific?
Does not have all the characteristics of life, cannot survive or reproduce without alone without a host, no metabolism, not made of cells

5. Virus Structure Bacteriophage 2. Tail 1.Capsid – made of protein,
Infects bacterial cells
1.Capsid – made of protein,
contains the genetic material
(DNA or RNA)
2. Tail
3.Tail Fibres- used for
attaching to target cell

6. HIV Influenza Antigens ‘The Flu’
Human Immunodeficiency
Virus
Influenza
‘The Flu’
1.Capsid – made of protein,
contains the genetic material
(RNA)
Antigens
- made of lipids/glycoproteins, help the virus to attack and enter their target
Also help the immune system to identify the virus

7. Flu Attack! How a Virus Invades Your Body
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8. Viruses Vocab
Viruses are obligate parasites – organisms that need to invade a living cell or being to survive and do not benefit them in any way
Host - The organism/cell that a parasite exploits
Viruses are pathogens – something that causes disease in the host cell/organism

9. What is a parasite?
What is a host?
What is a pathogen?

10. How Viruses Work
Step One – Viruses attach to their specific target cell based on their antigens. This works like a lock and key, so viruses will only affect certain cells.

11. Step Two – virus injects its genetic information into the host

12. Step Three – Replication (copies)The cell now starts to make copies of the virus proteins and genetic information
Step Four –Assembles-the different parts of the virus are assembled into full virus copies

13. Step Five – LYSIS (cell bursting apart) and the virus copies are released to infect other cells

14. What are the 5 steps of the Lytic Cycle?
1. attack
2. inject
3. replicate
4. assemble
5. Lysis

15. How Viruses Work

16. Lytic/Lysogenic Cycles
Viruses can infect cells in two different ways
Lytic Cycle (short cycle)If a virus enters and immediately causes infection with the 5 steps Ex. flu

18. Lytic/Lysogenic Cycles
Viruses can infect cells in two different ways
Lysogenic Cycle (long cycle) If a virus enters and remains dormant/inactive in the DNA before causing infection ex. HIV, Herpes

19. I’m a Virus! Rap Song

20. Immune Response-Your immune system recognizes viruses and bacteria based on their surface antigens
Every cell in your body has your specific markers, so anything that looks different is marked by your body as an invader
(this is why people need specific organ transplants and also why you can’t receive blood transfusions from everyone)

21. Immune Response
The Immune System protects the body in two ways:
1. Nonspecific Response: Skin, mucus, sweat, tears, saliva, stomach acid,and inflammatory response (heat, redness, swelling, and white blood cells)
2.Specific Response: Body makes antibodies which seek out and kill specific antigens

22. Immune System, part 1: Crash Course A&P #45

23. Brace yourself for the next slide!!
Immune Response
The immune system is incredibly complex which is why it has an entire branch of science called immunology
Brace yourself for the next slide!!

24. Specific Response
There are many cells that are responsible for the specific immune response:
Macrophages/Phagocytes- Large cells that ‘eat’ the virus/bacteria and show the T Cells and B Cells the antigen to target
Helper T Cells – Cells that tell B Cells, Cytotoxic T Cells, and Natural Killer Cells what to do
B Cells – Cells that make Plasma Cells and Memory B Cells
Plasma Cells – Cells that make antibodies which target the virus/bacteria
Memory B Cells- Cells that ‘remember’ the antigen so they can quickly kill the virus/bacteria if it shows up again later
Cytotoxic T Cells – Cells that make poison granules to kill the virus/pathogen
Natural Killer Cells - Cells that kill any infected or out of control (cancer) cells

25. Specific Response
HIV attacks Helper T Cells which greatly weakens the immune system This is how HIV (the virus) causes AIDS - Acquired Immunodeficiency Syndrome (the disease)

26. Medication
Antibiotics are medications that kill living cells so they are used against living pathogens like bacteria, (useless against viruses)
Viruses are very difficult to target with medications because they are not living by our definition of life

27. Antibiotics treat strep throat, ear and sinus infections, pneumonia, any type of bacteria infection.

28. Vaccines help fight viruses.
A vaccine actually contains weakened (dead, wrong use of the word) viruses that trigger the immune system to start making antibodies which will protect you in the future

29. Some Vaccines that are available
Keep in mind that not all
vaccines are 100% effective
Currently available vaccines:
*Hepatitis A, B
Adenovirus
HPV
Anthrax
Influenza (The Flu)
Japanese Encephalitis
Measles, Mumps, Rubella, Varicella
Rabies
Smallpox
Meningococcal
Typhoid
Shingles
Yellow Fever
Varicella (Chickenpox)

30. Which of the following are viruses?

31. BACTERIA
Virus

32. flu cold HIV H1N1 E. coli Herpes Staph infection Swine Flu Virus
Rhinovirus
flu
Influenza virus
HIV
Herpes