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Lesson 2

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Lesson 2

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Lesson 2

  1. 1. Lesson 2 Завдання до уроку з теми “Viruses, Viroids, Prions” Students have to read the information about viruses and viroids and fill in the chart Viruses Viroids: the plant invaders! A virus is an infectious agent with both living and non-living characteristics that is totally dependent on a host cell for replication. Viruses contain only either DNA or RNA (but not both), and a protein coat, which encases the nucleic acid. They have no homeostasis, metabolism, no respond to the stimuli, and they don’t grow or develop. They are able to infect all organisms. A viroid is a VIR (virus) OID (like) particle, a “sub-virus” composed exclusively of a single circular strand of nucleic acid (RNA). In other words, Viroids are small, circular RNA molecules without a protein coat. Viroids infect plants only! Task 1 Fill in the chart with the characteristics which describe viruses, viroids, or both. Virus vs viroid Needs host cell to reproduce, protein coat, no protein coat, infectious agent, DNA and RNA, RNA, infects all organisms, infects plants, no cell, needs host cell to reproduce viruses viroids
  2. 2. Keys Viruses: Protein coat DNA RNA Infect all organisms Both: Infectious agent No cells Need host cells to reproduce Viroids: No protein coat RNA Infect plants Task 2: LISTENING FOR COMPREHENSION : Listen to the text and fill in the chart Characteristics of prion diseases and the specific properties of causative agents Infection-carrying proteins are called prions. They have neither DNA nor RNA. It appears that they cause fatal human brain diseases. Years may pass between getting infected and having symptoms, as the incubation period lasts from months to years, while the progressive course lasts from weeks to months. What makes these diseases especially dangerous is the fact that there is no immune response, so that it makes it almost impossible to detect them. If detected, prion diseases have no specific treatment. The causative agents have no detectable nucleic acid. They are resistible to alcohol, formalin, heat, and UV irradiation.
  3. 3. Characteristics of prion disease Student’s answers Incubation period Progressive course Host immune response Specific treatment Keys Characteristics of prion disease Student’s answers Incubation period From months to years Progressive course From weeks to months Host immune response no Specific treatment no Task 3: Listen to the text for the second time and fill the gaps while listening Characteristics of prion diseases and the specific properties of causative agents Infection-carrying proteins are called _______. They have ____ DNA __ RNA. It appears that they cause _____ human _______ diseases. Years may pass between _______________ and _________________, as the incubation period lasts from _______________, while the progressive course lasts from _______________. What makes these diseases especially dangerous is the fact that there is no ___________________, so that it makes it almost impossible to _________ them. If detected, prion diseases have no ____________________. The causative agents have no detectable _______________. They are resistible to alcohol, formalin,______, and UV ____________.

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