Layer # 1:What is a Virus? ~ A small, nonliving particle that invades and then reproduces inside a living cell. ~ Biologists consider viruses to be nonliving because viruses are not cells. Do not meet all characteristics of living organism.
~ Only living characteristic is their ability to multiple. ~ This process is special because it requires a host cell. ~ A host is a living thing that provides a source of energy for a virus or an organism. ~ Organisms that live on/in a host causing harm are parasites. ~Viruses are like parasite because they destroy their host cell to multiply.
~ No organisms are safe from viruses. ~ Viruses are special in the specific cells they infect. Cold viruses typically infect cells of the nose and throat.
Layer #2Naming Viruses • Since viruses are nonliving, normal names are not assigned. • They are named after the disease they cause, founder or the organism they infect. • The Ebola Virus was named after the location in Africa where it was discovered.
Layer #3Shapes and Sizes of Viruses Rod Shaped: linear Spherical Shaped: actually 20 sided polygons. • These are the smaller virus types. • Smaller in animals and plants. • Virtually undetectable under even the most powerful of microscopes. • 20 – 250 nanometers • Average 50 – 60 nanometers
Bacteriophage • With its six legs, the bacteriophage attaches to the surface of the much larger bacteria • Once attached, the bacteriophage injects DNA into the bacterium. The DNA instructs the bacterium to produce masses of new viruses.
Layer #4Structure of Viruses All viruses have two basic parts: an outer coat that protects the virus and an inner core made of genetic material.
Coat • Outer coat made of certain proteins that allow it to fit into certain host cells. • Because this is so specific a virus will only attach to one or a few types of cells. • Example: HIV can only attach to one kind of human white blood cell.
Layer 5 How viruses multiply 1.Attatch and enter the cell 2.The virus’s genetic material takes over the cell 3.The genetic material instructs the cell to make the virus’s proteins and genetic material 4. The new proteins and genetic material make new viruses
Active Viruses Immediately goes into action after entering the cell. Like a photocopy machine left in the “on” position the virus When the host cell is full the cell bursts open releasing the newly made viruses
Hidden Viruses The genetic material does not immediately become active, but instead the viruses genetic material becomes a part of the cell and does not cause damage. Stays inactive for a period of time and for reasons not understood by scientists the virus will become active and begin the replicating process.
Layer 6:Viruses and the living world Some viruses are mild (cold), while others are more serious (AIDS) Viruses occur in other organisms (not just humans). Ex: 1. Rice dwarf virus = stunts growth or rice plants. 2. Rabies virus can infect humans, dogs, cats, foxes, etc.
Going from “bad” to “good”? Scientists are trying to take advantage of the way a virus gets into a cell. The new technique is called GENE THEROPY. Scientists add important (good) genetic material to a virus and use the virus as a messenger service. Ex. People with cystic fibrosis do not have the genetic material they need to keep their lungs functioning properly.
What? • A small, nonliving particle that invade and then replicates inside a living cell. • Non-living, does not have any characteristics of a living organism. Just because I quack like a Duck!
~ Viruses can only multiply when they are inside a living cell. ~ Viruses require a host ~ Host Cells- living things that provide a source of energy for a virus or an organism ~ Viruses are like parasites because they cause harm, destroy the cells in which they multiply.
What’s in a name? Viruses do not belong to any living kingdom. They are named from organisms they infect, scientists that discover them, where they are found, or what symptoms they cause.
Multiplication x2 Lytic Cycle: Takes over genetic material of the cell. Cell is programed to produce the proteins and genetic material of the virus. This is then assembled as a virus. Kills the cellhttp://www.youtube.com/watch?v=Rpj0emEGShQ Lysogenic Cycle: Virus injects genetic material into living cell. It then becomes part of the cells genetic material. Now the cell is reproducing every cell with virus inside. When stressors to the body occur, the dormant virus activates moving into the Lytic cycle. http://www.youtube.com/watch?v=41aqxcxsX2w
Bacteriophageriophage Virus that attacks prokaryotic cells (bacteria) Can be useful to kill disease causing bacteria Virus that attacks prokaryotic cells (bacteria) Can be useful to kill disease causing bacteria or Can infect the good bacteria or Can infect the good bacteria
The Bacteria Cell In the late 1600s a Dutch business man named Anthony Van Leeuwenhoek. While looking through one of his microscopes at scrapings from his teeth he saw the tiny organisms. Bacteria: are prokaryotes. Their cells do not have nuclei that contain the cell’s genetic material.
Cell Shapes: Spherical (cocci) Rod (bacilli) Spiral (spirilla)
Cell wall: surrounds the cell and protects it Cytoplasm: region inside the cell membrane. Ribosomes: chemical factories where proteins are produced. Flagellum: long, whiplike structure that helps bacteria move. Cell structures
Two Kingdoms 1st Archaebacteria: “ancient bacteria: These bacteria have existed for billions of years before dinosaurs appeared. Live only in extreme environments such as hot springs (110 degrees Celsius), salty waters, intestines of animals, mud in the bottom of swamps, sewage.
2nd Eubacteria: do not live in extreme environments, they live everywhere else. On and inside of your body (coat your skin, swarm your nose) – most are useful or harmless. Help maintain Earth’s physical conditions such as using the suns energy to produce oxygen – these are called autotrophs.
Reproduction Bacteria reproduce by binary fission: a process where one cell divides to form two identical cells. Conjugation: one bacterium transfers some of its genetic material into another bacteria cell through a threadlike bridge. After the transfer, the cells separate.