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Chapter 20.1 Viruses Goal: To learn the structures of viruses and prokaryotes, how they reproduce and their effects on the human body The Discovery of Viruses A virus is a nonliving particle made up of ____________, __________ __________ and sometimes lipids. Structure and Composition Viruses are extremely small; and can only be seen with an ____________ microscope. The ___________ makes up the protein coat of a virus. Most animal viruses, like influenza, also have an additional coat of phospholipids. Viruses can have a _______ genes or ______________ of genes. Viruses have proteins on the surface of their membrane and use them to ___________ to other cells they infect. The proteins on the virus __________ the host cell into letting the entire virus in or just its _____________ material. Viruses are very specific meaning plant viruses typically infect____________, animal viruses infect certain species of ___________ and bacterial viruses only infect certain types of ______________. A _____________________ is a virus that infects bacteria. Make a diagram using Figure 20-1 Viral Forms T4 Bacteriophage Tobacco Mosaic Virus Influenza Virus 1 Viral Infections Once inside a host cell the virus will use its genetic material to take ____________of the cell and make multiple _________ of the virus. Lytic and Lysogenic Infections There are two types of infection; ________ infections and _____________ infections. A lytic infection occurs when a virus enters the cell, makes copies of the virus and causes the cell to ___________. A lysogenic infection occurs when a virus enters a cell and doesn’t take over the cell ______________but will later cause disease. The viral DNA that becomes imbedded into the hosts DNA is called a ________________. Make a diagram using Figure 20-3 2 A Closer Look at Two RNA Viruses 70 percent of viruses contain _______ rather than _______. Human RNA viruses include the common cold, HIV and even some forms of ___________. A virus that uses its RNA to make DNA is known as a ____________. HIV is an example of a retrovirus. Viruses are ______________ since they depend entirely on other living things for their existence and often harm the host. Outline the Common Cold Infection Mechanism from page 578 Outline the HIV Infection Mechanism from page 578 3 Use the Venn diagram to list the similarities and differences between viruses and cells. Use the chart on page 579 to complete the diagram. 4 20.2 Prokaryotes Classifying Prokaryotes Prokaryotes are single celled organisms that lack a __________ so their DNA is in the cytoplasm. Bacteria and Archaea Prokaryotes are classified into ___________ and ____________. Bacteria are found everywhere on earth. Bacteria have a _________ _________ made up of sugars and amino acids called a ___________________ that surrounds the cell membrane. Some bacteria have _____________ for movement and _________to anchor to surfaces. Make a diagram using Figure 20 – 7 Typical Bacterial Structure Archaea look similar to bacteria but their cell walls lack a ________________ and their DNA sequences (genes) are more similar to _______________than bacteria. Archaea produce methane gas and live in ____________ environments that may contain little to no oxygen such as bogs and the digestive tracts of animals. Some Archaea live in extremely salty environments or in hot springs that approach the boiling temperature for water. 5 Structure and Function Size, Shape, and Movement Prokaryotes differ in their shape, movement and the way they obtain their _____________. Bacteria come in three shapes; _____________ (bacilli), _____________shaped (cocci) and____________ shaped (spirilla) Some bacteria do not move at all while some have ____________ to help propel on a gel like substance they secrete. Nutrition and Metabolism Use figure 20 -10 on page 582 to show the varied ways prokaryotes obtain and release energy. Energy Capture by Prokaryotes Mode of |Nutrition How Energy Is Captured Habitat Example 6 Energy Release by Prokaryotes Mode of Metabolism How Energy is Released Habitat Example Growth, Reproduction and Recombination ____________ ____________ is a type of asexual reproduction that occurs when a cell doubles in size and then divides in half creating two identical cells. Binary fission is considered to be a form of____________ reproduction since there is no exchange of ____________ material. Binary fission happens very rapidly and can occur as quickly as every 20 minutes. When the environment is unfavourable some prokaryotes can for an ___________. An endospore has thick walls protecting the ___________and cytoplasm and this allows the prokaryote to stay ______________ for long periods of time until the environment becomes more favourable. 7 Genetic variation can occur two ways even though prokaryotes reproduce asexually. One method is when a mutation in their _________ occurs and the mutation is passed on to a daughter cell. Another method is through _____________ where a hollow bridge forms between two cells and a ___________ (ring of DNA) is transferred. The transfer of genetic material ____________ genetic variation in the population. The Importance of Prokaryotes Decomposers, Producers, Nitrogen Fixers and Human Use Prokaryotes play an important role in maintaining the ecological balance of the environment. Prokaryotes break down or ______________ dead organisms and by doing this they provide the raw materials for other organisms to use. ___________________ are also important in sewage treatment plants, purifying water and chemicals used in fertilizing. Photosynthetic prokaryotes are the most abundant primary __________________ in the environment. Prokaryotes have the ability to fix _____________ from the environment and turn it into a useful form so other organisms can turn it into ________________ and other molecules. Humans use prokaryotes to produce yogurt, digest petroleum and remove wastes and poisons from water. 8 20.3 Diseases Caused by Bacteria and Viruses Bacterial Diseases ________________ are disease causing agents. Louis Pasteur was the first to discover that bacteria cause disease and he established the ___________ ___________ of disease. Disease Mechanisms Bacteria produce disease in one of two ways: ______________ Tissue Bacteria will enter the body and begin to grow and this results in an ____________ response that destroys large areas of tissue. _____________ Toxins Bacteria will produce _________ (poisons) that will travel through the body and damage tissue, blood vessels and organs. Finish the following chart on Controlling Bacteria Physical Removal Using a refrigerator to keep foods at low temperatures. Disinfectants Heating instruments at temperatures above 1000 C Food Processing 9 Preventing and Treating Bacterial Infections Bacterial infections can be prevented by receiving a ________________. A vaccination is made of weakened or dead pathogens which are injected into the body to cause an _______________ response to that specific pathogen. Some vaccinations will protect you for years or a life time. _______________ are used to treat bacteria. They disrupt the production of the cell membrane and cause the bacteria fall apart. Viral Diseases Disease Mechanisms, Preventing and Treating Viral Infections Viruses attack and destroy certain cells in the body. Viruses will also affect the ______________ and development of cells and at times cause ____________. Viruses can be prevented by using __________________, hand washing, avoiding contact with sick individuals and coughing into a tissue or sleeve. Viruses cannot be treated with __________________ but there are several antiviral drugs that attack specific viral _______________. Emerging Diseases Superbugs and New Viruses An unknown disease that appears for the first time or a wellknown disease that becomes difficult to treat is known as an ______________ ______________. With the increased ability for people to travel and produce being shipped around the globe there is a greater possibility of spreading new diseases. The danger of emerging diseases is that people have little to no _________________. 10 The widespread use of _____________ has led to natural selection that favours bacteria that are resistant to antibiotics. Common bacteria have become ____________ _________ resistant making them very difficult to control especially when they are spread very easily. 11