Biology: Homologous Chromosomes
http://mindbites.com/lesson/1468-biology-homologous-chromosomes Professor Wolfe proposes two problems that have to be overcome during meiosis. One problem is that offspring have to have the same number of chromosomes as the parents, which means that the cells used in sexual reproduction need to have half the number of chromosomes as normal somatic cells. This means that meiotic division has to produce haploid cells. The second problem is the sorting of chromosomes. Each offspring will have to have not just the correct number of chromosomes, but also all the correct types of chromosomes. These two problems can be overcome by understanding that humans don't just have 46 chromosomes, but 23 pairs of chromosomes. A diploid cell is a cell with two copies of each chromosome. Sexual reproduction uses homologous chromosomes, which are chromosome pairs that have the same genetic composition but are derived from different parents. This lesson is perfect for review for a CLEP test, mid-term, final, summer school, or personal growth! Taught by Professor George Wolfe, this lesson was selected from a broader, comprehensive course, Biology. This course and others are available from Thinkwell, Inc. The full course can be found at http://www.thinkwell.com/student/product/biology. The full course covers evolution, ecology, inorganic and organic chemistry, cell biology, respiration, molecular genetics, photosynthesis, biotechnology, cell reproduction, Mendelian genetics and mutation, population genetics and mutation, animal systems and homeostasis, evolution of life on earth, and plant systems and homeostasis. George Wolfe brings 30+ years of teaching and curriculum writing experience to Thinkwell Biology. His teaching career started in Zaire, Africa where he taught Biology, Chemistry, Political Economics, and Physical Education in the Peace Corps. Since then, he's taught in the Western NY region, spending the last 20 years in the Rochester City School District where he is the Director of the Loudoun Academy of Science. Besides his teaching career, Mr. Wolfe has also been an Emmy-winning television host, fielding live questions for the PBS/WXXI production of Homework Hotline as well as writing and performing in "Football Physics" segments for the Buffalo Bills and the Discover Channel. His contributions to education have been extensive, serving on multiple advisory boards including the Cornell Institute of Physics Teachers, the Cornell Institute of Biology Teachers and the Harvard-Smithsonian Center for Astrophysics SportSmarts curriculum project. He has authored several publications including "The Nasonia Project", a lab series built around the genetics and behaviors of a parasitic wasp. He has received numerous awards throughout his teaching career including the NSTA Presidential Excellence Award, The National Association of Biology Teachers Outstanding Biology Teacher Award for New York State, The Shell Award for Outstanding Science Educator, and was recently inducted in the National Teaching Hall of Fame.