Viruses (1) PPT Presentation PDF

Organisms at the edge CHAPTER 19: VIRUSES AND PROCARYOTES book page :596-608 WHAT ARE VIRUSES? ARE VIRUSES LIVING? Properties of Living Properties of Viruses Organisms Breathes (respires) Doesn’t breathe Metabolizes Doesn’t metabolize Grows Doesn’t grow Repro...

Organisms at the edge CHAPTER 19: VIRUSES AND PROCARYOTES book page :596-608 WHAT ARE VIRUSES? ARE VIRUSES LIVING? Properties of Living Properties of Viruses Organisms Breathes (respires) Doesn’t breathe Metabolizes Doesn’t metabolize Grows Doesn’t grow Reproduces Reproduces A virus is an infectious microorganism consisting of a segment of nucleic acid (either DNA or RNA) surrounded by a protein A pathogen is usually coat. defined as a WHAT microorganism that ARE causes, or can cause, VIRUSES? disease. VECTORS - Organism or object that transmits a virus Ex’s: Rats insects birds VIRULENCE- Degree in A VIRUS is either DNA or RNA, that is protected by a protein coat called a CAPSID.  How s m al l is a vi rus ?  Viruses range in size from 20 nanometers (nm) – 250 nanometers (nm) 1 nm = 0.00000004 inches If a cell was the size of your classroom, then an average virus would be the size of a softball. proteins animal atom viruses bacteria cells 0m 10-6 m 10-5 m 10-7 m 10-8 m 10-9 m Go five more feet! 10-10 m Viroids are infectious pathogens that affect only plants, therefore are also called plant pathogens. Structurally, viroids are smaller than viruses and possess circular strands of ribonucleic acids (RNAs) with no protein coating. They are passed via pollen or seeds The plants that are infected by viroids are responsible for the crop failures. Some of the plants that are affected by these pathogens are potatoes, tomatoes, cucumbers, chrysanthemums, coconut palms, avocados, etc.  A prion is a type of protein that can cause disease in animals and humans by triggering normally healthy proteins in the brain to fold The functions of these normal prion abnormally. proteins are still not completely understood. The abnormal folding of the prion proteins leads to brain damage and the characteristic signs and symptoms of the disease. Prion diseases are usually rapidly progressive and always fatal. A single viral particle called a virion is made up of genetic information in a “carrying case” — a protective coating called a capsid. The structure of virus Viruses aren’t made up of cells, so they don’t have all the equipment that cells do to make more copies of themselves. Instead, they carry instructions with them and use a host cell’s equipment to make more copies of the virus. It’s like someone breaking into your house to use your kitchen. The virus brought its own recipe, but it needs to use your dishes, measuring cups, mixer and oven to make it. (Unfortunately, they usually leave a big mess when you finally kick them out.)  DNA/RNA DNA or RNA code for genes that defines who we are. DNA, deoxyribonucleic acid, is the double-stranded molecule that encodes genetic information (e.g. your hair color, height, etc.) in the nucleus of cells. The complete set of DNA in a cell is called the genome. RNA, ribonucleic acid, is typically single stranded so that it can be read to make proteins. VIRAL SHAPE (4 TYPES) Viruses usually infect a specific host including: Who do Viruses infect Bacteria viruses  These viruses are called bacteriophages infect? Viruses infect Plants  One example is the Tobacco Mosaic Virus Viruses infect Animals  One example is the common cold POLYHEDRAL WITH A TAIL - BACTERIOPHAGE https://www.youtube.com/watch?v=oqYKPf7hnHs HOW DO THESE THINGS REPLICATE SO FAST???  REPLICATION PHASES I, II, III - Viruses enter cell Phase I - Attachment to cell membrane - Penetration inside cell - Losing virus protein coat IV - Replication - Tricks cell into making more viral DNA - Tricks cell into making viral protein coat V - Release Phase II - Assembly of virus DNA and protein coat into whole new viruses - Leaving the cell Phase III Phase V Phase IV https://www.youtube.com/watch?v=jkNxmTrrZSk Viruses cause two types of infections FIRST PATHWAY OF INFECTION LYTIC INFECTION SECOND PATHWAY OF INFECTION LYZOGENIC INFECTION COMMON VIRAL DISEASES COMMON VIRAL DISEASES COMMON VIRAL DISEASES COMMON VIRAL DISEASES