Unit 6 Lesson 1: BioFlexBook Questions
(1) Why do cells need to divide?
They divide to form two new cells when the body grows because the size of a cell is limited and can only help out the body by making more and more cells.
(2) How do single-celled prokaryotic cells divide? How do eukaryotic cells divide (mitosis)? How are these processes different? Similar?
Most prokaryotic cells divide by the process of binary fission which can be described as a series of steps but is a process that is continuous. Most eukaryotic cells divide by the process of mitosis which is a multi-phase process in which the nucleus of the cell divides. They are both similar because both processes have different steps. A different is prokaryotic cell division goes through the process of binary fission and eukaryotic cell division goes through the process of mitosis.
(3) What are the stages of mitosis and what happens during those stages?
The two stages of those process are mitosis then cytokinesis. In mitosis the nuclear membrane breaks down and later reforms. The chromosomes are also sorted and separated to ensure that each daughter cell receives a complete set of chromosomes. In cytokinesis the cytoplasm divides and two daughter cells form.
(4) What are the stages of meiosis and what happens during those stages?
The stages of meiosis are Prophase I, Metaphase I, Anaphase I, and Telophase I and Cytokinesis.
•Prophase I: The nuclear envelope begins to break down, and the chromosomes condense. Centrioles start moving to opposite poles of the cell, and a spindle begins to form. Importantly, homologous chromosomes pair up, which is unique to prophase I. In prophase of mitosis and meiosis II, homologous chromosomes do not form pairs in this way. During prophase I, crossing-over occurs.
•Metaphase I: Spindle fibers attach to the paired homologous chromosomes. The paired chromosomes line up along the equator of the cell. This occurs only in metaphase I. In metaphase of mitosis and meiosis II, it is sister chromatids that line up along the equator of the cell.
•Anaphase I: Spindle fibers shorten, and the chromosomes of each homologous pair start to separate from each other. One chromosome of each pair moves toward one pole of the cell, and the other chromosome moves toward the opposite pole.
•Telophase I and Cytokinesis: The spindle breaks down, and new nuclear membranes form. The cytoplasm of the cell divides, and two haploid daughter cells result. The daughter cells each have a random assortment of chromosomes, with one from each homologous pair. Both daughter cells go on to meiosis II.
(5) How is meiosis similar to mitosis? How is it different?
Both mitosis and meiosis are associated with cytokinesis. Meiosis has two rounds of genetic separation and cellular division while mitosis only has one of each.
They divide to form two new cells when the body grows because the size of a cell is limited and can only help out the body by making more and more cells.
(2) How do single-celled prokaryotic cells divide? How do eukaryotic cells divide (mitosis)? How are these processes different? Similar?
Most prokaryotic cells divide by the process of binary fission which can be described as a series of steps but is a process that is continuous. Most eukaryotic cells divide by the process of mitosis which is a multi-phase process in which the nucleus of the cell divides. They are both similar because both processes have different steps. A different is prokaryotic cell division goes through the process of binary fission and eukaryotic cell division goes through the process of mitosis.
(3) What are the stages of mitosis and what happens during those stages?
The two stages of those process are mitosis then cytokinesis. In mitosis the nuclear membrane breaks down and later reforms. The chromosomes are also sorted and separated to ensure that each daughter cell receives a complete set of chromosomes. In cytokinesis the cytoplasm divides and two daughter cells form.
(4) What are the stages of meiosis and what happens during those stages?
The stages of meiosis are Prophase I, Metaphase I, Anaphase I, and Telophase I and Cytokinesis.
•Prophase I: The nuclear envelope begins to break down, and the chromosomes condense. Centrioles start moving to opposite poles of the cell, and a spindle begins to form. Importantly, homologous chromosomes pair up, which is unique to prophase I. In prophase of mitosis and meiosis II, homologous chromosomes do not form pairs in this way. During prophase I, crossing-over occurs.
•Metaphase I: Spindle fibers attach to the paired homologous chromosomes. The paired chromosomes line up along the equator of the cell. This occurs only in metaphase I. In metaphase of mitosis and meiosis II, it is sister chromatids that line up along the equator of the cell.
•Anaphase I: Spindle fibers shorten, and the chromosomes of each homologous pair start to separate from each other. One chromosome of each pair moves toward one pole of the cell, and the other chromosome moves toward the opposite pole.
•Telophase I and Cytokinesis: The spindle breaks down, and new nuclear membranes form. The cytoplasm of the cell divides, and two haploid daughter cells result. The daughter cells each have a random assortment of chromosomes, with one from each homologous pair. Both daughter cells go on to meiosis II.
(5) How is meiosis similar to mitosis? How is it different?
Both mitosis and meiosis are associated with cytokinesis. Meiosis has two rounds of genetic separation and cellular division while mitosis only has one of each.