? Viruses Virus - an infectious agent made up of a core of nucleic acid and a protein coat. viruses are not cells, they are non-living does not have a nucleus, a membrane, or cellular organelles. do have organized structural parts All viruses have at least 2 parts: core of nucleic acid (DNA/RNA) capsid - protective protein coat around the core of nucleic acid. The capsid protects the nucleic acid core from its environment. Additional parts may include: an envelope is an additional protective coating usually made of lipids, proteins, and carbohydrates. spiked projections that bind to the membrane of the cell being infected. **envelopes are only found in viruses that infect animal cells (i.e. flu virus). IV. Vaccines
Chapter 19 Viruses Lecture Outline Overview: A Borrowed Life ? Viruses are the simplest biological systems. ? Most viruses are little more than aggregates of nucleic acids and protein?genes in a protein coat. ? Are viruses living or nonliving? ? Viruses cannot reproduce or carry out metabolic activities outside of a host cell. ? Most virologists would probably agree that viruses are not alive but lead ?a kind of borrowed life.? ? Molecular biology was born in the laboratories of microbiologists studying viruses that infect bacteria. ? Experiments with viruses provided key evidence that genes are made of nucleic acids. ? Viruses were critical in working out most of the major steps in DNA replication, transcription, and translation.
Previous IB Exam Essay Questions: Unit 10 Use these model essay questions and responses to prepare for essay questions on your in-class tests, as well as the IB Examination, Paper 3. The questions below have appeared on IB HL Examinations over the past several years. The answers following the questions are the markscheme ideal responses used to evaluate student examination responses. 1. Outline the experiments of Miller and Urey into the origin of organic compounds on Earth. 6 marks apparatus contructed in which chemicals could circulate gases of pre-biotic Earth`s atmosphere mixed inside methane (as a carbon source) ammonia water vapor and hydrogen sparks/ electric discharge (to simulate lightning) high temperature/ boiling water no free oxygen
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