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Mitosis & The Cell Cycle

Mitosis & The Cell Cycle. The 5 phases of the cell. Refresher on DNA. DNA is the master molecule of the cell. DNA is located in the nucleus of nearly every cell.

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Mitosis & The Cell Cycle

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  1. Mitosis & The Cell Cycle The 5 phases of the cell.

  2. Refresher on DNA • DNA is the master molecule of the cell. DNA is located in the nucleus of nearly every cell. http://www.3dscience.com/img/Products/3D_Models/Biology/DNA/DNA_w_Phosphate_structure/Supporting_images/3d_model_DNA_w_phosphate_1.jpg

  3. DNA

  4. Refresher on DNA • Genes are sections of DNA that are typically about 5000 nucleotides long. Genes are the directions for making a certain kind of protein for the cell. http://z.about.com/d/p/440/e/f/9344.jpg

  5. DNA Gene

  6. Refresher on DNA • Chromosomes are rod-shaped structures that contain long sections of DNA with hundreds of genes. Chromosomes can only be seen right before and during cell division. • During the other phases of the cell’s life, the DNA uncoils somewhat and exists as chromatin which is not visible with a light microscope.

  7. DNA Gene Chromosome

  8. Chromosomes vs. Chromatin http://www.microscopy-uk.org.uk/mag/imgnov04macro/metaphase.jpg http://images.google.com/images?gbv=2&svnum=10&hl=en&q=nucleus+TEM+chromatin

  9. Human Chromosomes (46) http://131.229.114.77/microscopy/images/Chromosomes2.jpg

  10. Development of an Embryo • The adult human body contains an estimated100 trillion cells. Therefore, we are considered to be multicellular organisms.

  11. Development of an Embryo • DNA is extremely important! DNA molecules are needed to store the directions on how to make new cells and to tell those new cells what their function within the body will be. However, every cell in the body has identical DNA.

  12. Differentiation • If every cell has identical DNA, why don’t all of the cells look and act the same? Because not all of the DNA is used. Various sections of the DNA are activated from one type of cell to the next. • This process of creating different cells using identical DNA is called differentiation.

  13. Cell Division Activation of certain genes Differentiation http://scienceblogs.com/clock/upload/2006/12/a2%20cell%20differentiation.gif

  14. Differentiation • So when, and how does a cell develop and differentiate? The process begins with the cell cycle. • Recall that all of us started out as one cell, a combination of egg and sperm. During development, cells first divide and later will begin to differentiate to form various body parts.

  15. The Cell Cycle • As we develop, our cells go through a cycle of events. The basic cell cycle looks like this:

  16. Phases of the Cell Cycle • M = Mitosis(& cell division) or sometimes Meiosis (making of gametes/sex cells). • G1 = Gap 1 During this phase cells are not resting! They are busy making proteins, breaking down toxic molecules, and using energy. • S = DNA replication or synthesis. During this phase the cell must make an extra copy of DNA to prepare for mitosis. • G2 = Gap 2 During this phase cells are again not resting! They are busy preparing for cell division.

  17. Differentiation • At first, cells go through the cell cycle rapidly and do not have time to differentiate, but at some point in development the cells stop dividing and begin to differentiate into different types of cells. (In other words, they remain in the G1 phase.)

  18. Differentiation • Some cells in the human body divideour entire lifetime. Our hair follicles, skin, and the lining of our digestive tract are examples of cells that constantly divide. These cells are fairly simple and mainly serve as barriers or boundaries.

  19. Differentiation • Some cells completely lose their ability to divide. Once they differentiate, they can no longer go back to this cycle. Muscle cells and cells of the central nervous system cannot be replaced once they are destroyed because of this.

  20. Differentiation • Some cells remain in the G1 phase most of the time. They can regain their ability to dividetemporarily in order to replace damaged cells, but will then go back into a mode of not dividing.

  21. Differentiation (or lack of) • Cancer: a simplified explanation of cancer cells is that these are cells that have gone into a rapid, repetitive cell cycle. Cells normally have mechanisms to prevent this from happening, but if a number of these preventative measures fail, cells can begin to multiply uncontrollably. Cancer cells do not have time to differentiate. They look different, do not function normally, and eventually squeeze out the normal cells that surround them. Cancer cells have a cell cycle that’s gone bad!

  22. The 5 phases of the cell • There are 5 recognizable phases of the cell: IPMAT • I = Interphase • P = Prophase • M = Metaphase • A = Anaphase • T = Telophase

  23. Interphase • Interphase includes the G1, S, and G2 cell cycle phases. • Cells spend most of their time in interphase. The only time that a cell can be seen in one of the other 4 phases is when the cell is in the process of dividing.

  24. Mitosis • Mitosis is paired with cell division: • Mitosis refers to the process when the chromosomes divide. • Cell division often refers to the process when the remainder of the cell (cytoplasm) divides, but this term can be used more generally as well. • Mitosis includes: prophase, metaphase, anaphase, and telophase.

  25. Interphase: most of the time the cell looks like this. Mitosis: The 4 phases of mitosis can be easily identified using a microscope.

  26. #1 • Which of these is prophase, metaphase, anaphase, telophase, and interphase? http://www.sep.alquds.edu/biology/scripts/Biology_english/part_3_4_files/image010.jpg

  27. #2 • Is this interphase, prophase, metaphase, anaphase, or telophase? http://biology.nebrwesleyan.edu/benham/mitosis/images/alliumtelophase.JPG

  28. #3 • Is this interphase, prophase, metaphase, anaphase, or telophase? http://www.instr.science.ru.nl/lichtmicroscoop/bf-division.jpg

  29. #4 • What phase is this? http://www.instr.science.ru.nl/lichtmicroscoop/bf-division.jpg

  30. #5 • What phase is this? http://chsweb.lr.k12.nj.us/psidelsky/onion_root_tip__1000_X__-10.jpg

  31. #6 • What phase is this? http://kcfac.kilgore.cc.tx.us/kcap1/images/whitefish%20mitosis%20telophase%201000x%20%20fireworks.jpg

  32. #7 • What phase is this? http://virtual.yosemite.cc.ca.us/randerson/Lynn's%20Bioslides/86.jpg

  33. #8 • What phase is this? http://virtual.yosemite.cc.ca.us/randerson/Lynn's%20Bioslides/94.jpg

  34. #9 • What phases are these? E A G C F D H B http://www.phschool.com/science/biology_place/labbench/lab3/images/anifield.gif

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