Viruses Something you don’t want to catch…. 1.Viruses a.How do scientists classify things as living? i.Made of cells ii.Has a metabolism to grow and reproduce

Viruses• Something you don’t want to

catch…

1.Viruses

a. How do scientists classify things as living?

i. Made of cellsii. Has a metabolism to grow and

reproduceiii. Information stored in DNA

b. Are viruses alive? NO!

1. Viruses

3. What do viruses and living organisms have in common?

i. Both use nucleic acids to store genetic information in the form of DNA or RNA

ii.Both change over time (evolve)

1.Viruses

4. If viruses do not have their own metabolism to grow and reproduce, how do they survive?

i. By hijacking living cells and using their metabolism to grow and reproduce.

2. Living or Nonliving?

Characterisitic Viruses Bacteria

Structure Capsid, DNA, Envelope DNA, Cell membrane, Cytoplasm

Reproduction

Growth

Obtains and Uses Energy?

Response to Environment?

Harms body by?

Living?




Reproduction Host cell needed Independent

Growth



Harms body by?

Living?





Growth No - assembled Yes



Harms body by?

Living?






Obtains and Uses Energy? No Yes


Harms body by?

Living?







Response to Environment? No Yes

Harms body by?

Living?








Harms body by? Disrupting Homeostasis Producing Toxins

Living?








Harms body by? Disrupting Homeostasis Producing Toxins

Living? No Yes

3. Virus Reproduction

a. First, the virus gains entry to the cell by connecting with cell receptors.

b. Second, the viruses’ DNA or RNA is injected into the cell.

3.Virus Reproduction

c. Third, viral nucleic acid replicates and takes over the cell.

3. Virus Reproduction

d. Fourth, new viralparticles are packagedand released fromthe cell.

4. 2 types of viral infectionsa. Lytic infection- a virus

enters a cell, makes copies of itself, and causes cell to burst .

b. Lysogenic infection- a virus integrates its DNA into the DNA of the host cell, and the viral genetic information replicates along with the host cell’s DNA.

Lytic vs. Lysogenicc. Viruses with lysogenic reproduction, lay dormant until the cell is replicated during mitosis.

WHAT’S THE DIFFERENCE?

2 Types of Viral Infection

Lytic - influenza Lysogenic - herpes

Lytic vs. Lysogenic

• Lytic

CHECK POINT

• Lysogenic

5. Virus Types

a. Bacteriophages = are viruses that attack bacteria

b. Retroviruses = viruses that use RNA to reverse transcribe DNA that integrates into the host genome.Example: HIV

6. How do you treat a virus?

a. Remember you cannot treat a viral infection but you can prevent one by getting a vaccine.

b. Viruses must be prevented.

a. Wash your handsb. Do not share drinks,

food, etc.c. Practice good hygeine

6.Vaccine

a. A vaccine improves

immunity to a particular disease.

6. How do vaccines work?

http://health.howstuffworks.com/adam-200097.htm

i. A vaccine contains a weakened strain of the microbe.

ii. When injected into your body it stimulates your immune system to recognize it as foreign, destroy it, and remember it.

iii. So if your body encounters the full strain later, it can easily recognize and destroy it!!!!!

Important facts about viruses

• Viruses must be produced within living cells

• Viruses destroy the living cells they grow in

• Viruses gain entry by specific receptors on the host cell

SUMMARY

Documents

Viruses Something you don’t want to catch…. 1.Viruses a.How do scientists classify things as living? i.Made of cells ii.Has a metabolism to grow and reproduce