3.2_Cellular_Reproduction - Now that we have learned about...

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Now that we have learned about cell structure and physiology, we will now look at how cells reproduce. 1
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After reviewing some fundamental concepts of cell theory, we will look very briefly at the reproduction of prokaryotes such as bacteria and then focus our attention on eukaryotes. 2
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First, let’s recall one of the basic tenets of biology called the cell theory: that cells give rise to cells. This occurs in two ways for multicellular eukaryotes- Mitosis which results in identical cell production – essentially clones of the original cell for the purpose of growth, cell replacement and repair tissue. And meiosis which is unique to sexually reproductive organisms that produce special cells with half of the genetic material called gametes. 3
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As just mentioned, prokaryotes and single-celled eukaryotes such as yeast undergo mitosis. This is often referred to as binary fission in bacteria where “bi-” refers to the two cells produced and fission refers to the separation of two separate daughter cells. Prior to division of the cell, the DNA is duplicated so that both cells receive the same genetic material. Genetic diversity within a population is derived from mutations and mechanisms of genetic exchange among individuals. A more powerful means of developing genetic diversity is through meiosis done by eukaryotes. 4
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Compared to prokaryotes, the DNA is more complex in eukaryotes and includes other molecules such as proteins. After the DNA is copied, the chromosomes become very compact. Note that the replicated chromosomes or sister chromatids are attached to each other by the centromere. 5
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Before we go on, we need to review some chromosome basics. This image is a mosaic of photographs of each of the human chromosomes prior to duplication. This shows the pairs called homologous pairs of chromosomes. Each pair has similar genetic information with one coming from the father and one from the mother. When DNA occurs in mitosis, each member of the pair will be duplicated and connected by the centromere. We will come back to some chromosome basics when we discuss meiosis later in the presentation. 6
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7 DNA duplication or synthesis occurs during a stage in the eukaryotic cell cycle called interphase. The mitotic phase involves the actual separation of the two copies of DNA called mitosis and the division of the cell referred to as cytokinesis.
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Let’s look at the mitotic phase. This involves a seamless process of dividing the DNA and cell contents to the two daughter cells; however, to help in understanding the complex process, people have separated the mitotic phase into stages. Our goal is to have a general understanding of each phase.
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3.2_Cellular_Reproduction - Now that we have learned about...

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