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DNA molecule described as double helix. PowerPoint Presentation
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DNA molecule described as double helix.

DNA molecule described as double helix.

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DNA molecule described as double helix.

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  1. DNA molecule described as double helix.

  2. WE EXPRESS OUR DNA • as we need it……….

  3. The ENTIRE DNA MOLECULE can Replicate: Then You have 2 from 1 (DNA REPLICATION---Leads to MITOSIS ..one cell goes to two cells. OR 2. Selected sections of the DNA strand(genes) can be expressed ( transcribed and into mRNA and Translated into proteins)

  4. We know that it is HIGHLY CONDENSED and COMPLEXED WITH PROTEINS Called HISTONES • Into complexes called NUCLEOSOMES …see next 2 SLIDEs. • HINT: REMEMBER the actual DNA molecule is a polymer of nucleotides as you view the next slide keep that in mind and watch the molecule condense and become “complexed” with proteins into nucleosomes.

  5. Duplicating Genetic Information Information about you is in the sequence of nucleotides in the DNA molecule In each of your cells, there is about 2 meters of DNA per nucleus How does the DNA condense into such as small area? DNA histones chromatin

  6. DNA

  7. Helicases: Unwind DNA Double Strand • Primers: Short strand of nucleotides • DNA polymerases: position nucleotides along the template DNA strand • DNA Ligases: Splice together short segments of new

  8. Humans Have 46 Chromosomes 23 pairs 2n is called the DIPLOID NUMBER 2n = 46 2 is the number of copies of each chromosome n = the number of different chromosomes 46 is the total number of chromosomes in the cell

  9. Duplicating Genetic Information

  10. Duplicating Genetic Information

  11. Duplicating Genetic Information

  12. Duplicating Genetic Information

  13. The Cell Cycle • Phases include: • Interphase – Preparation phases for mitosis • Mitosis – Cell division or splitting • Interphase Includes: • G1 (Growth) • S- Synthesis ( DNA STRAND IS REPLICATED ) • G2 (Growth) • MITOSIS INCLUDES: SEE SLIDES AHEAD The Cell Cycle

  14. G1 phase, the first gap phase • accumulates materials needed to replicate DNA • S phase, synthesis phase • DNA replication • G2 phase, second gap phase • replicates centrioles • synthesizes enzymes for division • M phase, mitotic phase • nuclear and cytoplasmic division • G0 phase, cells that have left the cycle • Cell cycle duration varies between cell types

  15. The organized series of events that takes place AFTER this DNA replication • It is an event of the homologous chromosomes • It is triggered by various stimuli in some but not all cells during very specific phase of “Cell cycle

  16. MITOTOTIC CELL DIVISION

  17. We say that cells in the G-0 phase have left the cell cycle. • These cell do not undergo cell division via cell mitosis • Examples: NEURONS, RED BLOOD CELLS,

  18. Cancer genes- stimulates mitosis when we should NOT have it. UNCONTROLLED GROWTH that lead to tumors. • Oncogene is a cancer gene. • Usually has a three letter name (ras)

  19. Your body carefully controls which cells divide and when they do so by using molecular stop and go signals. For example, injured cells at the site of a wound send go signals to the surrounding skin cells • BUT WHAT if these signals are confused? . Mitosis then becomes a weapon turned against the body, spurring the growth of invasive tumors

  20. Understanding Cancer Series: Cancer < Back to Main Understanding Cancer Series: Cancer < Back to Main Posted: 01/28/2005 Posted: 01/28/2005 Quick Links NCI Highlights Quick Links NCI Highlights Page Options Page Options Director's CornerDictionary of Cancer TermsNCI Drug DictionaryFunding OpportunitiesNCI PublicationsAdvisory Boards and GroupsNIH Calendar of EventsEspañol Director's CornerDictionary of Cancer TermsNCI Drug DictionaryFunding OpportunitiesNCI PublicationsAdvisory Boards and GroupsNIH Calendar of EventsEspañol NCI Offers Support for Those in Need After KatrinaNCI Announces Plan to Fight Lung CancerNational Prostate Cancer Awareness MonthNational Ovarian Cancer AwarenessNCAB Working Group Report on Biomedical TechnologyThe Nation's Investment in Cancer Research FY 2006Past Highlights NCI Offers Support for Those in Need After KatrinaNCI Announces Plan to Fight Lung CancerNational Prostate Cancer Awareness MonthNational Ovarian Cancer AwarenessNCAB Working Group Report on Biomedical TechnologyThe Nation's Investment in Cancer Research FY 2006Past Highlights Print This Page Print This Page Print This Document Print This Document View Entire Document View Entire Document E-Mail This Document E-Mail This Document View/Print PDF View/Print PDF View/Print PowerPoint View/Print PowerPoint Slide 4 Loss of Normal Growth Control Cancer arises from a loss of normal growth control. In normal tissues, the rates of new cell growth and old cell death are kept in balance. In cancer, this balance is disrupted. This disruption can result from uncontrolled cell growth or loss of a cell's ability to undergo cell suicide by a process called"apoptosis." Apoptosis, or "cell suicide," is the mechanism by which old or damaged cells normally self-destruct. < Previous|Index|Next Slide > NCI Home A Service of the National Cancer Institute . | Text-Only Version | Contact Us | Policies | Accessibility | Site Help | Site Map | Text-Only Version | Contact Us | Policies | Accessibility | Site Help | Site Map

  21. WE WILL DISCUSS THE TOPIC OF CANCER in more detail in the next chapter, for now just and introduction to the idea that it is uncontrolled MITOTIC CELL DIVISION

  22. Why Mitosis Growth and Repair Products are identical copies of cells (clones)

  23. APOPTOSIS- programed ( neat and clean) cell death; occurs in fetus. Extra cells are neated destroyed. The lysosomes are organelles that facilitate this destruction. • Bad cells, cells destined to be cancerous are also destroyed this way.

  24. Cells divide when: • Have enough cytoplasm for 2 daughter cells • DNA replicated • Adequate supply of nutrients • Growth factor stimulation • Open space due to neighboring cell death Cells stop dividing when: • Loss of growth factors or nutrients • Contact inhibition

  25. Chromatin coils into genetically identical, paired, sister chromatids • each chromatid contains a DNA molecule • remember: genetic material (DNA) was doubled during S phase of interphase • Thus, there are 46 chromosomes with 2 chromatids/chromosome and 1 molecule DNA per chromatid.

  26. Nuclear envelope disintegrates • Centrioles sprout microtubules that push them apart and towards each pole of the cell • spindle fibers grow towards chromosomes • attach to kinetochore on side of centromere • spindle fibers pull chromosomes towards cell equator

  27. Chromosomes line up on one equator • Mitosis spindles finished • spindle fibers (microtubules) attach centrioles to long centromere • shorter microtubules anchor centrioles to plasma membrane (aster)

  28. Enzyme splits 2 chromatids apart at centromere • Daughter chromosomes move towards opposite poles of cells with centromere leading the way • motor proteins in kinetochore move centromeres along spindle fibers as fibers are disassembled

  29. New nuclear envelopes formed by rough ER • Chromatids uncoil into chromatin • Mitotic spindle breaks down • Nucleus forms nucleoli