Series: Biology: Meiosis

Smiles

09/23/2009

~ Jared

I just watched this as a review for a physiology class. I have taken a semester of genetics already and had this stuff down pat but it has been awile since I have used the info. This was an excellent review and in ten minutes I feel like i can remember so much from my last class. Great teacher. I wish he had stuff to cover all my review needs!

Mitosis vs Meiosis

04/06/2009

~ thomisha

Great insight, easy and fast learning skills.

Below are the descriptions for each of the lessons included in the series:

• Biology: Sexual Reproduction and Role of Meiosis

  There are two types of reproduction, asexual reproduction and sexual reproduction. Asexual reproduction creates genetically identical offspring. Several types of asexual reproduction are binary fission, which occurs in bacteria, budding, which occurs in coral, and spores, which some plants produce.

  However, sexual reproduction is selected for, genetically. This is because sexual reproduction produces new genetic combinations in offspring that allow for more variety and competition. These genetic combinations are known as recombinant genes. However, sexual reproduction requires a reductive cell division, called meiosis, to produce gametes. Gametes are haploid sex cells, instead of the normal diploid somatic cells and are necessary to keep the correct number of chromosomes in DNA.

  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.

• 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.

• Biology: Meiosis: Prophase I

  In this lesson, Professor Wolfe starts to discuss the individual phases of meiosis, which are very similar to the phases of mitosis. Meiosis, however, requires two cell divisions because of the creation of haploid cells from the sister chromatids. Ninety percent of meiosis occurs in the first phase, known as Prophase I. In this phase, two very important events occur. The first is the formation of a tetrad through the process of synapsis. Synapsis is the pairing of homologous chromosomes, which form the tetrad structure. These tetrads create areas called chiasmata (chiasma, if singular), where homologous genetic material "crosses over," or is exchanged. This exchange of homologous genetic information will be very important in further study of meiosis.

  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.

• Biology: Disjunction and Meiosis II

  In this lesson, Professor Wolfe starts out with an overview of Meiosis and then discusses and explains the processes of both Meiosis I and Meiosis II. During the stages of meiosis I, homologous chromosomes pair and are segregated into separate cells. These stages include prophase I, metaphase I, anaphase I and telophase I. Professor Wolfe will explain what happens durring each of these different phases. He will focus specifically on what is happening with the cell's chromosomes during these phases. In prophase I, homologous chromosomes synapse and form tetrads. In metaphase I, homologous chromosomes organize and line up. In anaphase I, homologous chromosome pairs separate, and in telophase I, a cleavage furrow forms, creating two cells. Each created cell has one chromosome from each homologous pair.

  During the stages of meiosis II, the doubled chromosomes are divided and move into separate cells as in mitosis. Meiosis II is also made up of stages (prophase II, metaphase II, anaphase II and telophase II), and you will also learn what happens in each of these phases, again with a focus on what is going on with the chromosomes. In prophase II, the nuclear envelope breaks down and spindle fibers form. In metaphase II, chromosomes line up on the metaphase plate. In anaphase II, chromatids separate, and in telophase II, haploid cells are eventually created. After meiosis II there are four cells, each containing the haploid genetic complement. This is the objective of Meiosis: to reduce the number of chromosomes by half (to form haploid cells) and to segregate homologous chromosomes.

  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.

• Biology: Mitosis vs. Meiosis

  In this lesson, mitosis and meiosis are compared in terms of DNA replication, the number of divisions, the presence of synapsis, the number of daughter cells, and the numbers of chromosomes in the products and function. This lesson is a good overview of both meiosis and mitosis, and explanation of why they are important and an analysis of how they are similar and different. Professor Wolfe reiterates, "Meiosis->Gametes; Mitosis->Everything Else."

  From a similarity standpoint (between meiosis and mitosis), in both: DNA is replicated and the process consists of phases (prophase, metaphase, anaphase, telophase). On the flip side, Meiosis and Mitosis differ along the following dimensions: number of divisions (1 for mitosis and 2 for meiosis), synapsis is only a characteristic of meiosis (in prophase I), the number of daughter cells produced varies (4 non-identical haploid cells in meiosis and 2 identical cells in mitosis), the number of chromosomes in resulting cells varies (2N in mitosis to match the original parent cell and only N in meiosis as the resulting cells are haploid), and the function/objective of the processes vary (somatic cells are produced via mitosis and gametes are produced by meiosis).

  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.