Viruses – Microbiology Questions and Answers

Viruses – Microbiology Questions and Answers Are viruses living or nonliving? nonliving Why might some people consider viruses alive? -can be killed -crystallized like table salt can viruses be killed? yes Can a virus maintain homeostasis like cells? No Are viruses cellular or non cellular non Virus non cellular particle made up of genetic material and protein that can invade living cells 2 main things that make up a virus genetic material and protein who coined the term virus and what does it mean? Beijerinck means poisons how were viruses first discovered Wendell Stanley crystallized sap from sick tobacco plants what did Wendell discover? viruses were made of nucleic acid and protein Who founded the vaccine against smallpox? What milder virus was used to make the vaccine? Edward Jenner -used milder cowpox virus virulent virus deadly viruses are said to be virulent How does the size of a virus compare with that of a cell? viruses are smaller than the smallest cell what metric units are used to measure the size of viruses? nanometers What technology had to be developed before viruses can be seen? electron microscope in the 20th century size of viruses from 20 nm to 250 nm what covers the outside of a virus? protein coat called the capsid what is in the core of a virus? DNA or RNA (not both) when and how can a virus reproduce? only when inside a host cell what protective covering is around the capsid of some viruses? protective envelope viruses only attack __ host cells specific capsomeres indivdual subunits outside of a host cell, viruses are __ inactive Do viruses have ribosomes like cells? lack ribosomes Do viruses have enzymes like cells? lack enzymes needed for metabolism Viruses use the __ and __ of its host cell to be able to __ raw materials enzymes reproduce viral diseases: smallpox, AIDS, measles, mononucleosis, influenza, colds, warts, Ebola virus free cells are rare in ? plants animals & humans what type of cancer is thought to be caused by viruses? leukemia what shape is ebola? helical shaped what shape is influenza? polyhedral shaped familiar names for viruses end in what suffix? -viridae genus names for viruses end in? -virus viral species group of viruses sharing the same genetic information and ecological niche (hosts) __ names are used for different species of viruses common how is the subspecies for a virus designated? by a number what virus causes blisters that may appear around the mouth? simplex 1 & 2 what virus is responsible for the common cold? adenovirus what virus causes warts? papillomavirus 4 things used to identify viruses: -RNA or DNA virus -do or do NOT have an envelope -Capsid shape -host they infect -if nucleic acid is single-stranded or double-stranded bacteriophage viruses that attack bacteria 3 characteristics of T-phages: -icosahedral heads -double -stranded DNA -tails Most commonly studied T-phages : T4 & T7 T-phages often attack what bacterial cell? Where is the host cell found? E.coli, an intestinal bacteria what is the only part of the virus that enters the host cell? viral DNA what is the shape of the bacterial host cell that bacteriophages attack? icosahedral how many sides does the head or capsid of a bacteriophage have? 20 triangular surfaces T-bacteriophages have what nucleic acid at their core? DNA What are the head and tail fibers made of? protein what nucleic acid do retroviruses contain? RNA What enzyme do retroviruses contain that let them make DNA from RNA reverse transcriptase What 2 things do retroviruses inject into their host cells when they attack them? RNA & reverse transcriptase enzyme Examples of Retroviruses HIV, AIDS, Feline Leukemia Virus viroids are responsible for causing what major problem in Europe? potato famine in Ireland Viroids resemble __ pieces of DNA that are cut out because they do not code for any proteins introns prions are infectious pieces of protein how do prions occur? they are normal body proteins that get converted into an alternate configuration by contact with other prion proteins do prions have a nucleic acid core? no DNA or RNA what protein is responsible for most mammalian prion disease? mammalian prion diseases called "PrP" what happens when prions get into the brain? they form insoluable deposits in the brain- causing neurons to rapidly degenerate What does BSE stand for and what is the common name for this prion disease? Bovine spongiform encephalitis (mad cow disease) explain the prion disease caused kuru New Guinea people suffered from kuru, which they go from eating the brains of their enemies what is the envelope of viruses often made from? What is the function of an envelope? they are made from the host cell membrane; protection 5 steps of lytic cycle 1. attachment to cell 2. penetration (injection) of viral DNA or RNA 3. Replication (biosynthesis) of new viral proteins and nucleic acids 4. maturation of the new viruses 5. release of the new viruses into the environment (cell lyses) what does the virus inject into its host? its nucleic acid What viral parts are made inside a cell? Where do the raw materials come from? viral proteins and nucleic acids; from the viral DNA or RNA injected into the cell latent viruses viruses that have the ability to become dormant inside the cell what activates latent viruses? activates in response to some external signal to produce new viruses Examples of latent viruses: HIV & herpes during the lysogenic cycle, what jappend to the viral nucleic acid after it is injected into the host cell? they don't always replicate very fast, they usually stay dormant in the cell what causes the phage or viral DNA to start replicating ? when an activation signal occurs does the prophage start replicating right after it is injected into the host cell? viral DNA (part of prophage) may stay inactive in host cell for long periods of time Viral DNA along with the host cell DNA is replicated during each __ binary fission once a prophage cell is activated, what happens? host cell enters the lytic cell once the prophafe is active, the host cell __ making the virus deadly or __ lyses virulent example of a disease that stays dormant in the nervous system tissue for many years -chickenpox (appears later in life as shingles- painful, itchy rash) -herpes (latency) how long does a herpes infection last? a person's lifetime genital herpes is called Herpes Simplex 2 cold sores or fever blisters are known as Herpes Simplex 1 how are some viral vaccines made? can be made from an attenuated, less virulent strain of the virus How does an attenuated virus help protect us from disease? attenuated virus is capable of stimulating an immune response & creating immunity, but not causing illness What proteins do our cells make to help protect us from viruses? interferon- naturally occuring proteins made by cells to fight viruses what is AZT? antiviral drugs how do protease inhibitors work to stop viruses? prevent capsid formation