Mitosis And Meiosis


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Mitosis And Meiosis

  1. 1. Mitosis and Meiosis By: Richard Shirk, Jr.
  2. 2. What Are Mitosis And Meiosis? <ul><li>Both are types of reproduction used during the cell cycle </li></ul><ul><li>Each type of cell division are specialized for different types of cells </li></ul><ul><li>Both undergo the cell cycle in very similar, yet very different ways </li></ul>
  3. 3. Important Definitions <ul><li>DNA : a molecule composed of deoxyribose nucleotides and contains the genetic information of living cells </li></ul><ul><li>Chromosome : a single DNA double helix together with proteins that help to organize the DNA </li></ul><ul><li>Chromatid : one of the two identical strands of DNA and protein that forms a replicated chromosome </li></ul><ul><li>Gene : a unit of heredity; specifies the amino acid sequence of proteins and hence particular traits </li></ul><ul><li>Allele : one of several alternative forms of a particular gene </li></ul><ul><li>Locus : the physical location of a gene on a chromosome </li></ul>
  4. 4. Important Definitions (cont.) <ul><li>Diploid : referring to a cell with pairs of homologous chromosomes </li></ul><ul><li>Haploid : referring to a cell that has only one member of each pair of homologous chromosomes </li></ul><ul><li>Homologous Pair : two homologues that are similar in appearance and genetic information that pair during meiosis </li></ul><ul><li>Heterozygous : carrying two different alleles of a given gene </li></ul><ul><li>Homozygous : carrying two copies of the same allele of a given gene </li></ul>
  5. 5. Mitosis <ul><li>Mitosis is the division of chromosomes in a cell </li></ul><ul><li>Usually followed by cytokinesis or cell division </li></ul><ul><li>Daughter cells produced after mitosis have same number of chromosomes as original cell </li></ul><ul><li>Purpose of mitosis is replication of somatic cells and asexual reproduction </li></ul><ul><li>Somatic cells include all cells in the body except the egg or sperm </li></ul>
  6. 6. Meiosis <ul><li>Meiosis is the division and reduction of the chromosomes of a cell </li></ul><ul><li>Daughter cells produced have half the chromosomes as the original cell </li></ul><ul><li>Purpose of meiosis is the production of gametes (sex cells) </li></ul>
  7. 7. Stages Of The Cell Cycle <ul><li>Interphase </li></ul><ul><li>Synthesis </li></ul><ul><li>Prophase </li></ul><ul><li>Metaphase </li></ul><ul><li>Anaphase </li></ul><ul><li>Telophase </li></ul>
  8. 8. Interphase And Synthesis Stages Of Mitosis And Meosis <ul><li>During Interphase the cell carries out normal activities such as metabolism and protein synthesis </li></ul><ul><li>During synthesis the DNA in each chromosome is replicated </li></ul>
  9. 9. Prophase And Metaphase Stages of Mitosis <ul><li>The prophase stage </li></ul><ul><ul><li>chromosomes condense and would be visible under a light microscope </li></ul></ul><ul><ul><li>the nuclear membrane degrades </li></ul></ul><ul><li>In the metaphase stage the chromosomes line up along the equator </li></ul>
  10. 10. Anaphase And Telophase Stages of Mitosis And Cytokinesis <ul><li>In the anaphase stage the sister chromatids separate and move to opposite ends of the cell </li></ul><ul><li>In the telophase stage one set of each chromosome reaches each pole </li></ul><ul><li>Cytokinesis begins and the cell divides in two creating two diploid cells </li></ul>
  11. 11. Meosis I <ul><li>Prophase I </li></ul><ul><ul><li>chromosomes visible </li></ul></ul><ul><ul><li>hHomologous pairs of chromosomes come together to from tetrads </li></ul></ul><ul><ul><li>crossing over occurs when a chromatid of one chromosome in a pair exchanges a segment of itself with the chromatid of the other chromosome in the pair </li></ul></ul>
  12. 12. Meosis I (cont.) <ul><li>Metaphase I </li></ul><ul><ul><li>homologous pairs line up along the equator of the cell </li></ul></ul><ul><li>Anaphase I </li></ul><ul><ul><li>Homologous pairs of chromosomes separate and move to opposite poles of cell </li></ul></ul><ul><li>Telophase I </li></ul><ul><ul><li>Chromosomes complete their migration to poles of the cell and cytokinesis occurs </li></ul></ul>
  13. 13. Meosis II <ul><li>No new DNA replication takes place </li></ul><ul><li>Prophase II </li></ul><ul><ul><li>Spindle fibers re-form and chromosome begin to move to middle of cell </li></ul></ul>
  14. 14. Meosis II (cont.) <ul><li>Metaphase II </li></ul><ul><ul><li>chromosomes line up along equator </li></ul></ul><ul><li>Anaphase II </li></ul><ul><ul><li>sister chromatids of each chromosome separate and move to poles of cells </li></ul></ul><ul><li>Telophase II </li></ul><ul><ul><li>the chromatids complete migration </li></ul></ul><ul><ul><li>nuclei reform and cytokinesis occurs </li></ul></ul><ul><li>Meosis produces four haploid cells </li></ul>
  15. 15. Crossing Over Of Meosis <ul><li>Increases the number of allelic combinations </li></ul><ul><li>Increase in different possible physical expressions and characteristics </li></ul><ul><li>Allows species to try varies combinations and find the best combination that suits their environment </li></ul>
  16. 16. Works Cited <ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul>