Cell Division
Cells <ul><li>Somatic </li></ul><ul><li>Regular Cells </li></ul><ul><li>Have 46 Chromosomes </li></ul><ul><li>2N Diploid –...
Cell Cycle <ul><li>The cycle of growth, mitosis and cytokinesis. </li></ul>
Interphase <ul><li>The longest phase of the cell cycle </li></ul><ul><li>Gap one- Cell prepares for DNA and chromosome rep...
Mitosis
Early Prophase <ul><li>The DNA and proteins condense and become visible. </li></ul><ul><li>Centrioles begin to move apart....
Late Prophase <ul><li>Centrioles are on opposite sides of the nucleus. </li></ul><ul><li>Microtubules called spindle fiber...
Metaphase <ul><li>Homologous Pairs held by a centromere. </li></ul><ul><li>The Kinetochores allow the spindle fibers to at...
Anaphase <ul><li>The centromeres split and daughter chromosomes migrate to opposite ends of the poles. </li></ul><ul><li>C...
Telophase <ul><li>Nuclear envelope begins to reform around each group of chromosomes. </li></ul><ul><li>Chromosomes begin ...
Cytokinesis <ul><li>The division of the cytoplasm. </li></ul><ul><li>This process compartmentalizes the two new nuclei int...
Mitosis <ul><li>Maintains a constant amount of genetic material and a constant set of genes from generation to generation....
Mitosis Chromosome # <ul><li>If a parent cell is diploid, this results in two genetically identical progeny diploid cells,...
Mitosis and Cancer <ul><li>Cell division is controlled by specific chemical reactions that act as check points. </li></ul>...
Cells <ul><li>Cells come from other cells. </li></ul><ul><li>When an organism develops progeny cells will begin to differe...
Cells <ul><li>Cells have a lifespan. </li></ul><ul><li>Some cells become terminally differentiated, they will go through A...
Cells <ul><li>Totipotent- cells that have the ability to differentiate into any cell type.  A true totipotent cell is the ...
Molecular Control of the Cell cycle – Internal Regulators <ul><li>Checkpoints are in place at the different points in the ...
<ul><li>G1 to S – determines if cell is ready for Synthesis </li></ul><ul><li>G2-M – Checks for all DNA to be replicated a...
Proteins are the Checkpoints <ul><li>Cyclins (protein) and Kinases (enzyme) are the regulators to the cell cycle. </li></u...
External Regulators <ul><li>Growth Factor- molecule that stimulates cell division </li></ul><ul><li>Growth Factors can com...
Cancer <ul><li>At current rates, over a third of the people who read your textbook will die of cancer    </li></ul><ul><l...
 
Mitosis Review <ul><li>Mitosis is for increasing cell number. </li></ul><ul><li>Mitosis is for individual organism growth ...
Meiosis <ul><li>Two successive divisions of a diploid nucleus with only one replication of DNA. </li></ul><ul><li>In anima...
Meiosis I <ul><li>First, interphase and DNA replication </li></ul><ul><li>Meiosis I is the first nuclear division. </li></...
Prophase 1 is Different in Meiosis  <ul><li>Homologous pairs exist (homologous is two sister chromatids connected at a cen...
Prophase 1 <ul><li>Synapsis: the formation along the length of the chromatids of a zipperlike structure which aligns the t...
Prophase 1 <ul><li>Tetrad: four chromatids in a synapsed set of homologous chromosomes. </li></ul>
Prophase 1 <ul><li>Crossing-over:  the exchange of chromosome segments at corresponding positions along pairs of homologou...
Crossing-over <ul><li>The exchange of corresponding genetic information produces new gene combinations in a population. </...
Recombination <ul><li>A chromosome that emerges from meiosis with a combination of genes that differ from what the chromos...
Prophase 1 <ul><li>After Genetic Recombination occurs the remaining steps in Prophase 1 are the same as Mitosis. </li></ul>
Metaphase 1 <ul><li>The homologs line up two by two on the equatorial plane versus one by one in Mitosis. </li></ul>
Anaphase 1 <ul><li>The tetrad separates, so that the homologous pairs disjoin and migrate toward a pole. </li></ul>
Anaphase 1 Difference from Meiosis <ul><li>At this time, the segregated sister chromatid pairs remain attached at the cent...
Telophase 1 <ul><li>The nuclear envelope is formed around the homologous pairs. </li></ul><ul><li>Cytokinesis begins. </li...
Cytokinesis <ul><li>Two cells that are 2N. </li></ul><ul><li>Ready to start Meiosis II </li></ul>
Meiosis II <ul><li>The second meiotic division similar to Mitosis. </li></ul>
Meiosis II, What is Different? <ul><li>The is no Interphase, NO SYNTHESIS of DNA. </li></ul><ul><li>You just go right into...
Meiosis II, What is the Difference? <ul><li>The chromosomes are not exact copies of the original chromosomes due to recomb...
 
Independent Assortment <ul><li>The factors for different traits assort independently of one another. </li></ul><ul><li>Bas...
Crossing-over and Independent Assortment. <ul><li>If  genes are located close together on a chromosome they have less chan...
Read Chapter 10
Chromosomes <ul><li>Two Types: Autosomal and Sex </li></ul><ul><li>22 Regular Autosomal Chromosomes and 2 Sex Chromosomes ...
Chromosome Structure <ul><li>DNA/ Gene  </li></ul><ul><li>Chromatin: sustainable material in a cell nucleus (DNA + Protein...
Chromosome Structure <ul><li>Nucleosome: is the basic unit of the chromatin ( the DNA wrapped around the histone with link...
 
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Cell division

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Cell division

  1. 1. Cell Division
  2. 2. Cells <ul><li>Somatic </li></ul><ul><li>Regular Cells </li></ul><ul><li>Have 46 Chromosomes </li></ul><ul><li>2N Diploid – set of chromosomes (two genomes) </li></ul><ul><li>Gametes </li></ul><ul><li>Sex Cells (egg/sperm; Pollen (sperm)/ovule (eggs) </li></ul><ul><li>Have 23 Chromosomes </li></ul><ul><li>N Haploid – one chromosome (a genome) </li></ul>
  3. 3. Cell Cycle <ul><li>The cycle of growth, mitosis and cytokinesis. </li></ul>
  4. 4. Interphase <ul><li>The longest phase of the cell cycle </li></ul><ul><li>Gap one- Cell prepares for DNA and chromosome replication </li></ul><ul><li>Synthesis- the DNA is replicated giving two exact copies called sister chromatids. </li></ul><ul><li>Gap two- cell grows for division and organelles duplicate. </li></ul>
  5. 5. Mitosis
  6. 6. Early Prophase <ul><li>The DNA and proteins condense and become visible. </li></ul><ul><li>Centrioles begin to move apart. </li></ul><ul><li>Nuclear envelope begins to disappear. </li></ul>
  7. 7. Late Prophase <ul><li>Centrioles are on opposite sides of the nucleus. </li></ul><ul><li>Microtubules called spindle fibers begin to form. </li></ul><ul><li>Chromosomes are in homologous pairs. </li></ul><ul><li>Nuclear envelope is gone. </li></ul>
  8. 8. Metaphase <ul><li>Homologous Pairs held by a centromere. </li></ul><ul><li>The Kinetochores allow the spindle fibers to attach at the centromere </li></ul><ul><li>The spindle fibers push and pull the homologous pairs to the middle of the cell called the metaphase plate. </li></ul>
  9. 9. Anaphase <ul><li>The centromeres split and daughter chromosomes migrate to opposite ends of the poles. </li></ul><ul><li>Centrioles and spindle fibers pull the daughter chromosomes towards the poles. </li></ul><ul><li>Cytokinesis begins </li></ul>Late anaphase
  10. 10. Telophase <ul><li>Nuclear envelope begins to reform around each group of chromosomes. </li></ul><ul><li>Chromosomes begin to become less visible. </li></ul><ul><li>Cytokinesis pinches in and cell membrane or cell plate begins to form. </li></ul>Animal Cell Plant Cell Cell Membrane
  11. 11. Cytokinesis <ul><li>The division of the cytoplasm. </li></ul><ul><li>This process compartmentalizes the two new nuclei into separate daughter cells. </li></ul>Animal Cell in Cleavage Furrow Cell Plate formation
  12. 12. Mitosis <ul><li>Maintains a constant amount of genetic material and a constant set of genes from generation to generation. </li></ul><ul><li>No genetic material is lost. </li></ul><ul><li>One copy of each duplicated chromosome segregates into a daughter cell. </li></ul><ul><li>2 cells at end of Mitosis. </li></ul>
  13. 13. Mitosis Chromosome # <ul><li>If a parent cell is diploid, this results in two genetically identical progeny diploid cells, each with two sets of chromosomes. </li></ul><ul><li>Or </li></ul><ul><li>If the parent cell was haploid the daughter cells will also be haploid. </li></ul>
  14. 14. Mitosis and Cancer <ul><li>Cell division is controlled by specific chemical reactions that act as check points. </li></ul><ul><li>When these signals are ignored by a cell, cancerous cells occur. </li></ul><ul><li>Cancer is a disorder where the body cells lose control of the growth of the cell. </li></ul>
  15. 15. Cells <ul><li>Cells come from other cells. </li></ul><ul><li>When an organism develops progeny cells will begin to differentiate. </li></ul><ul><li>Cell differentiation means that the cells become specialized as the fetus develops </li></ul><ul><li>or </li></ul><ul><li>they express different segments of genes then other cells and develop into a new cell form. </li></ul>
  16. 16. Cells <ul><li>Cells have a lifespan. </li></ul><ul><li>Some cells become terminally differentiated, they will go through Apoptosis or death and will be replace by younger cells. </li></ul><ul><li>The younger cells come from stem cells, which are a cell in the tissue that can self-renew. </li></ul><ul><li>Stem cells change or differentiate into specialized cells. </li></ul>
  17. 17. Cells <ul><li>Totipotent- cells that have the ability to differentiate into any cell type. A true totipotent cell is the first cells in an zygote or fertilized egg. </li></ul><ul><li>Pluripotent can develop into many kinds of cells but not all. </li></ul><ul><li>Multipotent cells can produce only the type of cells that are unique to a tissue. </li></ul>
  18. 18. Molecular Control of the Cell cycle – Internal Regulators <ul><li>Checkpoints are in place at the different points in the cell cycle. </li></ul><ul><li>Checkpoints look for damaged cells to repair or terminate. </li></ul>
  19. 19. <ul><li>G1 to S – determines if cell is ready for Synthesis </li></ul><ul><li>G2-M – Checks for all DNA to be replicated and SA:V ratio is correct. </li></ul><ul><li>If environment is not favorable the cycle will stop. </li></ul><ul><li>M checkpoint – determines if the chromosomes are attached to the spindles for chromosome separation. </li></ul>
  20. 20. Proteins are the Checkpoints <ul><li>Cyclins (protein) and Kinases (enzyme) are the regulators to the cell cycle. </li></ul><ul><li>The regular chemical reactions between these molecules keeps the cycle active or inactive. </li></ul><ul><li>Complicated signaling system. </li></ul>
  21. 21. External Regulators <ul><li>Growth Factor- molecule that stimulates cell division </li></ul><ul><li>Growth Factors can come from hormones or from the cells around the dividing cells. </li></ul><ul><li>Healthy cells will only grow and divide when there is a balance between growth factor and inhibitory signals. </li></ul>
  22. 22. Cancer <ul><li>At current rates, over a third of the people who read your textbook will die of cancer  </li></ul><ul><li>Tumors or neoplasms are tissue masses caused from non-normal cell growth. </li></ul><ul><li>Benign – not life threatening </li></ul><ul><li>Malignant – life threatening and disruptive to other tissues. </li></ul>
  23. 24. Mitosis Review <ul><li>Mitosis is for increasing cell number. </li></ul><ul><li>Mitosis is for individual organism growth and repair. </li></ul><ul><li>The loss of control of the Mitotic cycle leads to cancer. </li></ul><ul><li>The result is two identical cells with the same number of chromosomes as the Parent Cell. </li></ul><ul><li>In somatic cells – Nothing to do with heredity. </li></ul>
  24. 25. Meiosis <ul><li>Two successive divisions of a diploid nucleus with only one replication of DNA. </li></ul><ul><li>In animals the result is the formation of haploid gamete (gametogenesis) </li></ul>
  25. 26. Meiosis I <ul><li>First, interphase and DNA replication </li></ul><ul><li>Meiosis I is the first nuclear division. </li></ul><ul><li>Broken in to stages: </li></ul><ul><ul><li>Prophase 1 </li></ul></ul><ul><ul><li>Metaphase 1 </li></ul></ul><ul><ul><li>Anaphase 1 </li></ul></ul><ul><ul><li>Telophase 1 </li></ul></ul><ul><ul><li>Cytokinesis </li></ul></ul>
  26. 27. Prophase 1 is Different in Meiosis <ul><li>Homologous pairs exist (homologous is two sister chromatids connected at a centromere) </li></ul>Sister Chromatid Centromere
  27. 28. Prophase 1 <ul><li>Synapsis: the formation along the length of the chromatids of a zipperlike structure which aligns the two homologs precisely, base pair by base pair. </li></ul>
  28. 29. Prophase 1 <ul><li>Tetrad: four chromatids in a synapsed set of homologous chromosomes. </li></ul>
  29. 30. Prophase 1 <ul><li>Crossing-over: the exchange of chromosome segments at corresponding positions along pairs of homologous chromosomes. </li></ul>
  30. 31. Crossing-over <ul><li>The exchange of corresponding genetic information produces new gene combinations in a population. </li></ul><ul><li>Usually, no loss of addition to the genetic material because it is a reciprocal exchange along the synapse. </li></ul><ul><li>Chiasma is the site at where the crossing-over occurred and is visible in late prophase 1. </li></ul>
  31. 32. Recombination <ul><li>A chromosome that emerges from meiosis with a combination of genes that differ from what the chromosomes started with is a recombinant chromosome. </li></ul><ul><li>This is important in genetic recombination - variety in genetics in a species. </li></ul>
  32. 33. Prophase 1 <ul><li>After Genetic Recombination occurs the remaining steps in Prophase 1 are the same as Mitosis. </li></ul>
  33. 34. Metaphase 1 <ul><li>The homologs line up two by two on the equatorial plane versus one by one in Mitosis. </li></ul>
  34. 35. Anaphase 1 <ul><li>The tetrad separates, so that the homologous pairs disjoin and migrate toward a pole. </li></ul>
  35. 36. Anaphase 1 Difference from Meiosis <ul><li>At this time, the segregated sister chromatid pairs remain attached at the centromere. </li></ul><ul><li>Sister Chromatids stay together in meiosis, where as they would separate in Mitosis. </li></ul>
  36. 37. Telophase 1 <ul><li>The nuclear envelope is formed around the homologous pairs. </li></ul><ul><li>Cytokinesis begins. </li></ul>
  37. 38. Cytokinesis <ul><li>Two cells that are 2N. </li></ul><ul><li>Ready to start Meiosis II </li></ul>
  38. 39. Meiosis II <ul><li>The second meiotic division similar to Mitosis. </li></ul>
  39. 40. Meiosis II, What is Different? <ul><li>The is no Interphase, NO SYNTHESIS of DNA. </li></ul><ul><li>You just go right into prophase II! </li></ul><ul><li>End products are 4 haploid cells from one original diploid cell. </li></ul><ul><li>Each progeny cell has one chromosome for each homologous pair of chromosomes. </li></ul>
  40. 41. Meiosis II, What is the Difference? <ul><li>The chromosomes are not exact copies of the original chromosomes due to recombination. </li></ul><ul><li>Recombination generated more variation in genetic combinations. </li></ul>
  41. 43. Independent Assortment <ul><li>The factors for different traits assort independently of one another. </li></ul><ul><li>Basically this means, genes on different chromosomes separate independent of each other in Meiosis. </li></ul>
  42. 44. Crossing-over and Independent Assortment. <ul><li>If genes are located close together on a chromosome they have less chance to cross-over and assort independently. </li></ul><ul><li>If genes are located farther apart on the chromosomes they have are more likely to independently assort and recombine. </li></ul><ul><li>This can mean that some genes are almost always guaranteed to be on the same chromosome or found together (linkage). </li></ul>
  43. 45. Read Chapter 10
  44. 46. Chromosomes <ul><li>Two Types: Autosomal and Sex </li></ul><ul><li>22 Regular Autosomal Chromosomes and 2 Sex Chromosomes in Humans. </li></ul>
  45. 47. Chromosome Structure <ul><li>DNA/ Gene </li></ul><ul><li>Chromatin: sustainable material in a cell nucleus (DNA + Proteins) </li></ul><ul><ul><li>Proteins – Histones and Nonhistones </li></ul></ul><ul><ul><li>Histones- Protein with positive charge that the DNA is atracted to and coild around it. </li></ul></ul><ul><ul><li>Nonhistone- Proteins that play various roles in DNA replication and determine physical structure of the chromosome. </li></ul></ul>
  46. 48. Chromosome Structure <ul><li>Nucleosome: is the basic unit of the chromatin ( the DNA wrapped around the histone with linkers between histones. </li></ul><ul><li>The interactions between the histones make the DNA coil back onto itself to create a chromosome. </li></ul>

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