Viruses of COE university

Viruses Viruses Living or Not Living or Not ??????? ??????? Characteristics of Viruses Characteristics of Viruses  Among the smallest Among the smallest biological particles biological particles that are capable of that are capable of causing diseases in causing diseases in living organisms living organisms  Constructed of Constructed of compounds compounds associated with associated with cells cells Not Considered Living Not Considered Living  A virus is not a A virus is not a bacteria, fungus, bacteria, fungus, protist, plant or animal. protist, plant or animal.  They can not carry out They can not carry out cellular functions. cellular functions.  A virus can not A virus can not replicate without replicate without infecting cells and then infecting cells and then using the organelles using the organelles and enzymes of the and enzymes of the cells of the host. cells of the host. A Virus Has Two Essential Features A Virus Has Two Essential Features  A Nucleic Acid A Nucleic Acid  DNA or DNA or  RNA RNA  But not both But not both  A Capsid – a A Capsid – a protein coat protein coat surrounding the surrounding the nucleic acid. nucleic acid.  Some may have a Some may have a membrane like membrane like structure outside structure outside the capsid called the capsid called an envelop an envelop  Examples: Examples:  Influenza Influenza  Chickenpox Chickenpox  Herpes-simplex Herpes-simplex  HIV HIV Viral Shape Viral Shape  The shape of the virus is The shape of the virus is determined by either its determined by either its capsid or its nucleic acid capsid or its nucleic acid  Two examples of shape Two examples of shape  Icosahedron has 20 Icosahedron has 20 trianglular faces herpes trianglular faces herpes simplex, chicken pox and simplex, chicken pox and polio polio  Helix is a spiral shape Helix is a spiral shape ( like DNA) rabies, measles ( like DNA) rabies, measles and tobacco mosaic virus and tobacco mosaic virus There are Two Types of Viruses There are Two Types of Viruses  DNA DNA  Replicated in one of two ways Replicated in one of two ways  Directly produce RNA that make new Directly produce RNA that make new viral proteins viral proteins  Join with the host cell’s DNA to produce Join with the host cell’s DNA to produce new viral proteins new viral proteins  RNA RNA  Viral RNA is released into the host cell’s Viral RNA is released into the host cell’s cytoplasm and uses the ribosomes to cytoplasm and uses the ribosomes to produce new viral proteins produce new viral proteins  Some are known as retroviruses Some are known as retroviruses containing an enzyme called containing an enzyme called reverse transcriptase . These use the RNA as a . These use the RNA as a template to make DNA. This DNA is template to make DNA. This DNA is integrated into the host cell’s DNA integrated into the host cell’s DNA . . Viroid Viroid  Smallest known particles able to replicate Smallest known particles able to replicate  Short single strand of RNA Short single strand of RNA  No capsid No capsid  Disrupts plant metabolism and may damage Disrupts plant metabolism and may damage an entire crop an entire crop Prions Prions  Abnormal forms of proteins that Abnormal forms of proteins that clump in cells clump in cells  Linked to diseases of the brain Linked to diseases of the brain  Consist of 250 amino acids and not Consist of 250 amino acids and not associated with any nucleic acid associated with any nucleic acid  Examples: Examples:  Scrapies in sheep Scrapies in sheep  Mad Cow Disease in cattle Mad Cow Disease in cattle [...]... Mad Cow Disease    Mad cow disease, or bovine spongiform encephalopathy (BSE), is a fatal brain disorder that occurs in cattle and is caused by some unknown agent Brain cells die leaving the brain of the cow to look like a sponge It is believed to have come from a similar disease in sheep called scrapie Viral Replication . Viruses Viruses Living or Not Living or Not ??????? ??????? Characteristics of Viruses Characteristics of Viruses  Among the smallest. virus There are Two Types of Viruses There are Two Types of Viruses  DNA DNA  Replicated in one of two ways Replicated in one of two ways  Directly produce