Viruses & Prions

What is a virus??? What is a virus??? A virus is neither dead nor alive! A virus is neither dead nor alive! What is to be alive? What is to be alive? Characteristics for life... Characteristics for life Metabolism 1. Metabolism 2. Reproduction 2. Reproduction 3. DNA 3. DNA 4. Growth & Development 4. Growth & Development 5. Response to environment 5. Response to environment 6. Maintain internal environment 6. Maintain internal environment 7. Evolves 7. Evolves

Living organisms do not crystallize - viruses do. Living organisms do not crystallize - viruses do. Viruses are made-up of either DNA (like smallpox) or RNA (flu, HIV) and protein. Some viruses also have lipids. Viruses are made-up of either DNA (like smallpox) or RNA (flu, HIV) and protein. Some viruses also have lipids. A virus is basically a protein container (capsid) with nucleic acid inside. The only purpose of viruses is to reproduce. A virus is basically a protein container (capsid) with nucleic acid inside. The only purpose of viruses is to reproduce.

A virus is not considered alive since it must hijack the machinery of cells to copy itself. A virus is not considered alive since it must hijack the machinery of cells to copy itself. Viruses are generally specific as to what they infect. Viruses are generally specific as to what they infect. Plant viruses like the Tobacco Mosaic Virus, infect tobacco plants Plant viruses like the Tobacco Mosaic Virus, infect tobacco plants Animal viruses like influenza, infect certain animals (humans, pigs, ducks) Animal viruses like influenza, infect certain animals (humans, pigs, ducks) Viruses that infect bacteria are called a bacteriophage. Viruses that infect bacteria are called a bacteriophage.

Influenza Virus

Tobacco Mosaic Virus

Potato Virus

T4 Bacteriophage

Viral infection Viral infection When a virus has infected an organisms, there are two processes that can occur: When a virus has infected an organisms, there are two processes that can occur: Lytic infection or Lysogenic infection Lytic infection or Lysogenic infection In lytic infection - as is the case with bacteriophage T4 - a virus enters a cell, makes copies, and causes the cell to burst (Lyses). In lytic infection - as is the case with bacteriophage T4 - a virus enters a cell, makes copies, and causes the cell to burst (Lyses). In lysogenic infection the virus integrates its genetic material into the DNA of its host. Then the host cell replicates its DNA along with the viral DNA - thus producing viruses indefinitely. In lysogenic infection the virus integrates its genetic material into the DNA of its host. Then the host cell replicates its DNA along with the viral DNA - thus producing viruses indefinitely.

Retrovirus Retrovirus These viruses contain RNA instead of DNA as their genetic material. A retrovirus gets its name "retro - meaning backwards" because it copies RNA to DNA. These viruses contain RNA instead of DNA as their genetic material. A retrovirus gets its name "retro - meaning backwards" because it copies RNA to DNA. Retroviruses can cause cancer in animals and some are well known such as HIV and Influenza. Retroviruses can cause cancer in animals and some are well known such as HIV and Influenza. Reverse Transcriptase??? Reverse Transcriptase??? Viroids Viroids Single-stranded RNA particle without capsid ~ usually a plant affecting disease. Single-stranded RNA particle without capsid ~ usually a plant affecting disease.

Retrovirus

Chicken Pox (Varicella)

Measles (MMR)

Smallpox (Variola)

Eradicated, but what about terrorism?

Smallpox

PRIONS??? PRIONS??? Mad Cow Disease or BSE (Bovine Spongiform Encephalopathy) and varient Creutzfeld-Jacob disease - the human form - are thought to be caused by pathogenic proteins called prions. Mad Cow Disease or BSE (Bovine Spongiform Encephalopathy) and varient Creutzfeld-Jacob disease - the human form - are thought to be caused by pathogenic proteins called prions.

MAD COW DISEASE MAD COW DISEASE Mad cow disease is caused by something called a "PRION". A prion is a protein that is mutant (different than the normal kind) and causes normal proteins to change into mutant proteins when they come into contact with them. Mad cow disease is caused by something called a "PRION". A prion is a protein that is mutant (different than the normal kind) and causes normal proteins to change into mutant proteins when they come into contact with them.

These pathogenic (disease causing) proteins can be obtained by eating tissue that contains it (like cow brains from an infected cow). These pathogenic (disease causing) proteins can be obtained by eating tissue that contains it (like cow brains from an infected cow). It can also be passed down from mother to offspring animal ~ cow (inherited). This is possible because proteins are built from the instructions found in the organism's genes (DNA). If the organism has a bad gene for this disease, it will be passed to the offspring. It can also be passed down from mother to offspring animal ~ cow (inherited). This is possible because proteins are built from the instructions found in the organism's genes (DNA). If the organism has a bad gene for this disease, it will be passed to the offspring.

The End