1. A Story about Fighting the Flu
DO NOW….
Draw a square on your paper.
Draw a triangle around the square.
Draw two different types of antennae extending from the triangle.
Draw several swiggly lines within the square.
Holly gets sick
A Story about Fighting the Flu
How does your drawing compare with Picture A on the next slide?

2. Picture A Influenza Virus Flu Virus Structure
Your drawing and picture A represent a virus. Align the
Parts you drew with the name of real virus parts from A.

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What are Viruses?
A virus is a non-cellular particle made up of genetic material and protein that can invade living cells.
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Size of Viruses
Viruses are much smaller than a prokaryotic and eukaryotic cells
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Characteristics
Non living structures: not a cell
Contain a protein coat called the capsid
Have a nucleic acid core containing DNA or RNA
Capable of reproducing only when inside a HOST cell: pseudo- parasite
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Characteristics
CAPSID
Some viruses are enclosed in an protective envelope
Some viruses may have spikes to help attach to the host cell
Most viruses infect only SPECIFIC host cells
DNA
For some viruses, the capsid is surrounded by lipid bilayer that contains viral proteins, usually including the proteins that enable the virus to bind to the host cells. This lipid and protein structure is called the virus envelope, and is derived from the host cell membranes.
ENVELOPE
SPIKES
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Capsid Structure
Viral capsids (coats) are made of individual protein subunits
Individual subunits are called capsomeres
CAPSOMERES
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Why are they nonliving?
Outside of host cells, viruses are inactive
Lack ribosomes to make enzymes needed for polypeptide synthesis & DNA replication.
Use the host cell’s organelles and enzymes to reproduce
EBOLA VIRUS
HIV VIRUS
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Viral Shapes
Viruses come in a variety of shapes
Some may be helical shape like the Ebola virus
Some may be polyhedral shapes like the influenza virus
Others have more complex shapes like bacteriophages
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Helical Viruses
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Polyhedral Viruses
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12. Used for Virus Identification
RNA or DNA Virus
Do or do NOT have an envelope
Capsid shape
HOST they infect
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13. Write your answer in your notebook .
Select a Position
From the perspective of the virus, is it best for a virus to kill its host or to not kill its host?
Write your answer in your notebook .

14. Which is better?
To Kill
Not to Kill

15. Holly Gets Sick Pre-video
Watch video and try to answer questions Listen for specific types of human cells which help Holly to live or not.
Holly Gets Sick Pre-video
Successful Virus Infection:
Entry – just getting into body isn’t a guarantee
Spread – must get to the specific area in body
Multiply – infect specific cell type – go lytic!
Damage – cause illness
What will happen to Holly?

16. Bacteriophage (phage)
Virus which infects E.coli bacteria.
Phage uses tail fibers to attach to cell.
Only DNA is injected into cell.
Capsid remains outside cell.
Study picture to left. Notice only one
Phage completely without DNA (one
with white capsid.
Viral protein not needed inside cell
because it is the DNA that is the ]
information for making more virus.
Next slide shows the life cycle of a
Bacteriophage virus.
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17. Virus Life Cycles

18. Viral Diseases Some viruses cause disease
Smallpox, measles, mononucleosis, influenza, colds, warts, AIDS, Ebola.
Some viruses may cause some cancers like leukemia
Virus-free cells are rare
MEASLES
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19. How Body Fights a viral infection or any pathogen
Nonspecific: Doesn’t discriminate
Specific: Cells specifically id the virus
Fever
Macrophages
Nostril hairs, skin
Mucous
Natural Killer Cells
Interleukins
Antimicrobial proteins
Histamine and inflammation
Dendritic cell
Lymphocytes
T cells: Helper and Killer
B cells: makes antibodies
* Both specifically target the virus and mature in the lymph nodes
*Killer T and antibody destroy virus
Memory cell
Our immune system backs up our nonspecific defense system.

20. To the left is a macrophage using phagocytosis to
destroy bacteria. Below is a picture of tissue
damage showing macrophages destroying bacteria
at the site of tissue damage.
Illustration of tissue damage
Phagocytes (macrophages and neutrophils) consume bacteria and cell debris; tissue heals
Tissue injury; release of chemical signals such as histamine
Dilation and increased leakiness of local blood vessels; migration of phagocytes to the area

21. Not Required Information
B cells secrete antibodies that attack antigens ( anything foreign)
T cells attack cells infected with the
specific virus or pathogen.

22. Review questions
What is the difference between the lytic and lysogenic viral life cycles” What part of the virus remains outside the host cell? Goes into host cell? What part of the virus provides the genetic information to make more nucleic acid, capsids, envelopes and glycoprotein receptors? What part of the virus must be like the host cell? What is a vaccine? What are two ways in which you can achieve immunity from a infection? What is the difference between active immunity and passive immunity? Name all the types of immune cells and state their function. How can a viral or bacterial outbreak be prevented or controlled?