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Mitosis

Please wait 20 seconds before starting slide show. Mouse click to advance . Arrow keys etc.also work. Hit ESCAPE Key to exit. Mitosis. Part of Exercise 4 of Human Anatomy & Physiology Laboratory Manual, 8th Edition, by Elaine Marieb. Dr.Susan Maskel

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Mitosis

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  1. Please wait 20 seconds before starting slide show. Mouse click to advance. Arrow keys etc.also work. Hit ESCAPE Key to exit. Mitosis Part of Exercise 4 of Human Anatomy & Physiology Laboratory Manual, 8th Edition, by Elaine Marieb Dr.Susan Maskel BIO 105 Western Connecticut State University A&P I BIO 211 Naugatuck Valley Community College A&P I www.lawrencegaltman.com Some graphics and all definitions courtesy of Benjamin Cummings

  2. Background Information

  3. CHROMOSOMES

  4. DNA (deoxyribonucleic acid) stores genetic information CHROMOSOMES Protein controls processes

  5. DNA 2 strands double helix each strand contains: sugars (deoxyribose) phosphates (PO4) nitrogenous bases adenine thymine guanine cytosine

  6. O- -O - P = O O phosphate Structure of Components of DNA

  7. DNA S B B S P P S S Key: S = sugar P = phosphate B = base B B P P S B B S P P B B S S P P S B B S

  8. sugar-phosphate backbone nitrogenous bases form “rungs of ladder”

  9. Adenine (A) Thymine (T) Cytosine (C) Guanine (G) Specificity of base pairing A - T C - G Bases in DNA

  10. DNA

  11. Types of Chromosomes unduplicated (1 double stranded (ds) DNA + protein) duplicated(2 ds DNAs + protein)

  12. Duplicated Chromosomes DNA centromere sister chromatids

  13. Humans have 46 chromosomes in their somatic (i.e., not sperm or egg) cells. Diploid number = 2 N = 46 Humans have 23 chromosomes in their sex cells (sperm & egg). Haploid number = 1 N = 23

  14. THE CELL CYCLE

  15. At any given time, a cell is either: not dividing dividing

  16. When Cells are Not Dividing: • Interphase • G1 • Normal cell metabolism • Synthesis of proteins not used for mitosis • Chromosomes unduplicated • Centrioles replicate • S • Normal cell metabolism • DNA synthesis (DNA replication): unduplicated chromosomes  duplicated chromosomes • G2 • Normal cell metabolism • Synthesis of proteins used for mitosis • Chromosomes duplicated

  17. DNA Replication • DNA unzips • New nucleotides (sugar-phosphate-base combinations) add according to specificity of base pairing

  18. old strand new strand forming sister chromatid of duplicated chromosome

  19. NOTE: The 2 forming sister chromatids have an identical base sequence to each other.

  20. ds DNA of unduplicated chromosome Semiconservative Replication: each sister chromatid has 1 new & 1 old strand sister chromatids of duplicated chromosome

  21. When Cells Are Dividing: • Nuclear Division • Mitosis • occurs in somatic cells • maintains the # of chromosomes • Meiosis • occurs in sex cells • halves the # of chromosomes • Cytokinesis • division of cytoplasm • occurs during mitosis & meiosis

  22. G1 unduplicated chromosomes S chromosomes duplicate G2 duplicated chromosomes M start with duplicated chromosomes; end with unduplicated chromosomes

  23. Mitosis in Animals

  24. Before mitosis begins, the cell is in INTERPHASE.

  25. INTERPHASE • cell is not dividing • includes G1, S & G2 • nuclear membrane visible • nucleoli visible • chromatin in nucleus • NOT PART OF MITOSIS

  26. Interphase NOTE: • nuclear membrane intactnucleolus visiblechromatin not visible

  27. Interphase Nuclear membrane present Chromatin not visible

  28. Interphase

  29. Nuclear division in somatic cells takes place via MITOSIS.

  30. prophase metaphase MITOSIS anaphase telophase

  31. PROPHASE (1 - several hours) • nuclear membrane disappears • nucleoli disappear • chromatin  chromosomes • centrioles move to opposite poles of cell • spindle & asters form

  32. Centrioles made of microtubules at end of G1, centrioles replicated (to form 2 pairs)

  33. Spindle & Asters aster probably anchors apparatus to cell membrane spindle helps organize chromosomes during mitosis

  34. Prophase NOTE: nuclear membrane disappears nucleolus disappearschromatin  chromosomesspindle & asters form In this hypothetical cell, 2 N = 4. In humans, 2 N = 46.

  35. Prophase chromosomes Nuclear membrane still present but is disappearing

  36. Prophase

  37. METAPHASE (5 - 15 minutes) • chromosomes line up on center of spindle • chromosomes are attached to spindle fibers in area of centromere

  38. Metaphase NOTE: chromosomes lined up in single file in center of spindle In this hypothetical cell, 2 N = 4. In humans, 2 N = 46.

  39. Metaphase aster Chromosomes lined up on center of spindle aster

  40. Metaphase

  41. ANAPHASE (2 - 10 minutes) • spindle fibers pulled toward opposite poles of cell • centromeres splits • sister chromatids pulled toward opposite poles of cell as microtubules of spindle shorten

  42. Anaphase NOTE: sister chromatids being pulled toward opposite poles of cell In this hypothetical cell, 2 N = 4. In humans, 2 N = 46.

  43. Anaphase aster chromatids separated & being pulled toward opposite poles of cell aster

  44. Anaphase

  45. TELOPHASE (10 - 30 minutes) • cleavage furrow formed • cell invaginates at cleavage furrow until 2 daughter cells formed (= cytokinesis) • opposite of prophase • nuclear membrane reappears • nucleoli reappear • chromosomes uncoil to  chromatin • spindle & asters disappear

  46. Telophase NOTE: cleavage furrow forms;2 daughter cells will form; the opposite of prophase will occur In this hypothetical cell, 2 N = 4. In humans, 2 N = 46.

  47. cleavage furrow Telophase unduplicated chromosomes unwinding unduplicated chromosomes unwinding

  48. Telophase spindle

  49. INTERPHASE PROPHASE METAPHASE ANAPHASE TELOPHASE TELOPHASE

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