Belle Vernon Area School District / Overview



Name KEYMicrobiology Chapter 6: An Introduction to Viruses6.2 The Position of Viruses in the Biological Spectrum Are viruses alive? Why or why not?No because they cannot reproduce on their own and reproduction is a characteristic of life.Instead of referring to viruses as organisms, they should be referred to as infectious particles and instead of alive or dead as active or inactive.Viruses are known as obligate intracellular parasites. What does this mean?“Obligate” means they won’t function/survive without it and “intracellular parasite” means the virus must infect another living cell, acting like a parasite. The virus uses the cellular parts to function and reproduce.Describe the genetic material a virus may possess.Diverse. May be DNA (either double stranded or single stranded.) Or, may be RNA (either double stranded or single stranded.)How do viruses reproduce?They infect functioning cells and use that cells organelles to copy it’s DNA, and its ribosomes to make proteins to make more virus parts. Do viruses have ribosomes? What does this mean?No, viruses do NOT have ribosomes. This means that they cannot make proteins from their DNA/RNA, which is only a blueprint. Proteins are what actually matter, so to make proteins they must infect another cell and use its ribosomes.6.3 The General Structure of Viruses How does the size of a virus compare to that of a bacterial cell?Fill in the table to give the function of each virus structure.StructureFunctionCapsid HeadMade of proteins. Holds and protects the genetic material.Genetic MaterialSingle or Double stranded DNA. OR, Single or Double stranded RNA. Internal ProteinsProteins connecting the capsid head to the neck of the virus; provides a strong, secure connection.NeckConnects capsid head to the tail sheath.Tail SheathAllows for movement and acts as a pathway for the genetic material to travel through when being “injected” into a host (the cell being infected.) Tail FibersCling to the outermost membrane of a host cell to provide attachment.PinsPierce the host cell’s membrane, creating holes for the genetic material to pass from the virus into the cell.End PlateHold and organizes the pins. What is the nucleocapsid?The “head” of the virus. Composed of the capsid and genetic material combined.What is reverse transcriptase (RT) and how do viruses use it to overtake the cells they infect?Synthesizes DNA from RNA, which is the opposite of what usually happens.Formal Assignment [10 Formal]: On a sheet of computer paper draw and color the structure of a virus. Label the key structures given in #2 and state the function.6.5 Modes of Viral Multiplication The diagram below shows the lytic verses the lysogenic cycle for viruses. Formal Assignment [10 Formal]: Write two properly formed complete paragraphs – one detailing the steps of the lytic cycle and the second detailing the steps of the lysogenic cycle.6.8 – Viruses and Human Health Fill in the table below to describe the following diseases caused by viruses.DiseaseDescriptionChicken PoxMost people are vaccinated against this disease today. It is also called varicella and is characterized by red, itchy bumps all over the body. It is usually accompanied by fever and typically occurs in children. This virus is also responsible for the shingles.PolioMost people are vaccinated against this disease today. Affects people differently – some may experience no symptoms, others may experience flu-like symptoms, but in extreme cases weakness or paralysis of parts of the body occur and last the rest of the person’s life.InfluenzaThe flu. Mutates quickly which is why a person must be vaccinated yearly. Infected people typically recover in approximately 3-5 days, but the flu is dangerous for small children and the elderly.RabiesPets are routinely vaccinated, but humans only receive treatment if suspected to be infected. If infected the brain swells, making the animal act “crazy,” leading to death.MeaslesMost people are vaccinated against the measles, which is also known as rubella. Measles starts with fever, runny nose, cough, red eyes, and sore throat. It’s followed by a rash that spreads over the body. Measles virus is highly contagious virus and spreads through the air through coughing and sneezing. This disease is dangerous amongst children as complications are common. Informal Assignment [20 Informal]: Use Chapter 6 in your book to (page 166) to identify five more diseases caused by viruses and then do some research to give a description.DiseaseDescription ................
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