Lesson 7.3 Viruses - PowerPoint Presentation PDF

Chapter 7 Lesson 3 What are Viruses? Pages 246 - 253  Lesson Objectives Identify what viruses are Determine the shape of viruses Describe replication in viruses Describes the harmful effects of viruses. Understand how the body fights viruses  Viruses A virus is a...

Chapter 7 Lesson 3 What are Viruses? Pages 246 - 253  Lesson Objectives Identify what viruses are Determine the shape of viruses Describe replication in viruses Describes the harmful effects of viruses. Understand how the body fights viruses  Viruses A virus is a strand of DNA or RNA surrounded by a layer of protein that can infect and replicate in a host cell. A virus does not have a cell wall, a nucleus, or any other organelles present in cells. Virus Shapes crystal, cylinder, sphere, and bacteriophage shapes.  Structure of bacteriophage A bacteriophage (often referred to as simply as phage) is a type of virus that specifically infects and replicates within bacteria. Are viruses living things? A virus is not a living thing because it does not have all the characteristics of a living organism. It can make copies of itself in a process called replication, but it must rely on a living organism to do so. That is, a virus must be inside a cell in order to replicate. The living cell that a virus infects is called a host cell  Fun time Find the rabbit  Fun time Find the little man  Replication Replication refers to the process by which viruses reproduce and create copies of themselves. In order to reproduce, a virus needs a host cell. ( the virus uses the host cell as a tiny factory to make thousands of new viruses) A virus can only attach to host cell with specific molecules on its cell wall or cell membrane. This molecules enable the virus attach to the cell wall. When a virus enters a host cell, it can either be active or latent (dormant). Latent viruses go through an inactive stage. They don’t reproduce right away.  Replication Mutations A Mutation is a change in genetic material As viruses replicate, their DNA or RNA frequently mutates, or changes. These mutations enable viruses to adjust to changes in their host cells. As a virus mutates, they are able to produce new ways to attach to host cells. These changes happen so rapidly that it can be difficult to cure or treat viral diseases before they mutate again. Replication Replication Video: replication in viruses  Viral Diseases Viruses cause many human diseases. Other viral diseases include: -Hepatitis B and C -Coronavirus Disease (Covid) -Acquired immunodeficiency  Viral Diseases Viruses also infect plants  Viral Diseases Once a virus is in your body, it attacks and destroys specific cells. This destruction of cells causes the symptoms of the disease. Some viruses cause symptoms soon after infection. For example, the influenza virus that causes flu, infect the cell linings of your respiratory system. The virus begins to replicate immediately. Flu symptoms such as runny nose and scratchy throat, usually appear within 2-3 days. Viral Diseases  Fun time Find the worm Fun time Fun time Fun time Fun time Fun time Fun time Fun time Fun time  Treating and preventing viral diseases Since viruses are constantly changing, viral diseases can be difficult to treat. Antiviral medicines can be used to treat certain viral diseases. These medicines stop the virus from entering the cell or from replicating. Note that antibiotics do not treat viral diseases. Like bacteria, viruses can rapidly change and become resistant to medicine. One of the best ways to prevent a viral infection is to limit contact with an infected human or animal. The most important way to prevent infections is by practicing good hygiene such as washing your hands.  Treating and preventing viral diseases Immunity Immunity comes from the Latin word immunis which means exempt or free. When people are infected with a disease, and they survive, their bodies generally develop some protection against that disease in case in comes again. This is an example of acquired immunity. When a virus infects a person, their bodies begin to make antibodies. An antibody is a protein that can attach to a pathogen and make it useless, by preventing it from attaching to a host cell. Antibodies help your body fight diseases.  Treating and preventing viral diseases Immunity Video: How antibodies work  Treating and preventing viral diseases Immunity Natural immunity is immunity you are born with. It occurs when a mother passes antibodies on to her unborn baby.  Treating and preventing viral diseases Immunity Vaccines A vaccine is a mixture containing material from one or more deactivated pathogens, such as viruses. the vaccine triggers the production of antibodies. After being vaccinated against a particular pathogen, the organism will not get as sick if exposed to the same pathogen again.  Video: How vaccines work  Research with viruses Because viruses can change very quickly, scientists must always be working on new ways to treat and prevent viral infections. Viruses have been used by some scientists to treat genetic disorders and cancer using gene transfer. Scientists use viruses to insert normal genetic information into a specific cell.  Review A virus is a strand of DNA or RNA surrounded by a strand of protein Viruses cause human diseases such as chicken pox and influenza. A person’s body produces proteins called antibodies that prevent an infection by viruses.  Which is made by the body to fight viruses? A)Bacteria B)Antibody C)Bacteriophage D)Proteins  Organisms that cause diseases are known as pathogen …………………….. vaccine A(n)………………… is made using pieces of deactivated viruses or dead pathogens  Which is not caused by a virus? A)Chicken pox B)Influenza C)Rabies D)Tuberculosis  Which statement correctly describes viruses? A)All viruses are latent B)All viruses contain DNA C)Viruses are considered living things D)Viruses do not have organelles