Gene Mutation
As the text mentions, genes mutate, change accidentally, and in mutating may cause a plant to have new characteristics. These mutations are important for the evolution of plants in natural environments, for breeding improved crops, and for studying how genes control plant metabolism and development. Some of the easiest mutations to study are the ones that cause visible changes in the plants. At the web site "Mutants of Maize" there are sets of descriptions and photographs corn, also called 'maize,' mutants. Study several of these and notice some of the many ways that plant development can be altered. Some of the mutants cause leaves to have white spots, so the mutation is probably preventing the plant from synthesizing the green pigment chlorophyll. As you look at photos of other mutants, can you guess what the mutated gene might be doing (or not doing)? Causing mutations is easy for plant scientists, understanding what the mutated genes do is the big problem.
Visit the Maize Gene Data Base web site
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Characteristics of Life: Exploring the Solar System
We are actively searching for life in the solar system, looking for 1) living bacterium-like creatures, 2) traces that life existed in the past on Mars and 3) evidence that life could still originate in the future on one of the moons of Jupiter or Saturn. The "National Aeronautics and Space Administration (NASA)" web site contains a great deal of information on this topic. The site is updated frequently, so you may have to use your own ingenuity to find a site related to searching for life, but once you arrive at the page entitled "Solar System Exploration", scroll down until you find a list of topics. There should be headings related to Pathfinder, Mars Global Surveyor, Galileo (which is in orbit around Jupiter) or Cassini (on its way to Saturn and its moon Titan, but it will not arrive there until about 2004). As you examine these web sites, notice that we are searching for life in very different types of places. Read the text in Box 1.1 in your text book, and think about how the various characteristics of life must be used as the basis for this exploration of the solar system.
Visit the National Aeronautics and Space Administration web site
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