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“ Chromosome Waltz”

Standard 2 Cell Division. “ Chromosome Waltz”. Chromosome. Condensed form of chromatin a threadlike structure of nucleic acids and protein Always paired with an identical copy of itself. Chromosome. CHROMATID. SISTER CHROMATIDS. Chromosome. Y. X. Types of Chromosomes. Autosomes

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“ Chromosome Waltz”

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  1. Standard 2 Cell Division “Chromosome Waltz”

  2. Chromosome • Condensed form of chromatin • a threadlike structure of nucleic acids and protein • Always paired with an identical copy of itself

  3. Chromosome CHROMATID SISTER CHROMATIDS

  4. Chromosome

  5. Y X Types of Chromosomes Autosomes • The 1st 22 pairs of Chromosomes in humans. Sex Chromosomes • 23rd pair • In females, the sex chromosomes are the 2 X chromosomes. • Males have one X chromosome and one Y chromosome. • The Y chromosome is what makes a baby boy.

  6. Types of Cell Division Asexual: Offspring are identical to parents Examples: Budding: yeast Binary Fission: bacteria Sexual: Offspring have a combination of genetic information from 2 parents (Sperm and Egg) Ex: Animals and Plants

  7. Why do cells divide? • Growth • Reproduction (Development) • Repair or Replace

  8. What Happens in Cell Division • Replicates the DNA exactly. • Movement of the two copies of DNA to opposite ends of the cell. • Separates into two daughter cells.

  9. both new cells are identical to the original (all cells except sperm & eggs do this) Mitosis(1 cell becomes 2)

  10. Cell Cycle Interphase • Chromosomes appear as threadlike coils (chromatin) • 90% of cell cycle • Three phases • G1- Growth • S- DNA Replication • G2- Growth (prepares to divide)

  11. Mitosis • Cell division occurs in a series of stages, or phases. • 4 stages • Prophase • Metaphase • Anaphase • Telophase PMAT

  12. Prophase "BEFORE" • Mitosis begins (cell begins to divide) • You can see chromosomes start to form Late Early

  13. Metaphase "MIDDLE" Chromosomes line up in the center of the cell

  14. Anaphase "ANTI" Chromatids or chromosomes separate and begin to move to opposite ends of the cell

  15. Telophase "TWO" • Two new nuclei form • Chromosomes appear as chromatin Mitosis ends

  16. Cytokinesis "Split" • Become two identical new cells • Half the size of the original

  17. Metaphase Interphase Prophase Anaphase Telophase What Stages of Mitosis can you find?

  18. What looks similar between mitosis and meiosis? What looks different? Prophase Interphase Mitosis Cytokinesis Telophase Metaphase Anaphase Meiosis

  19. Meiosis-The process in which gametes (sex cells) are made.

  20. Meiosis 1 cell becomes 4 cells called gametes Male gametes = Sperm Female gametes = Eggs

  21. Cells in your body include… • Somatic cells: Make up the various parts of your body including tissues and organs. • Diploid cells (Full set of 23 chromosome pairs) • Gametes: sex cells – eggs in females and sperm in males. • Haploid cells (1/2 required # chromosomes)

  22. The Difference? Meiosis is Mitosis twice without Interphase in between & Mitosis is in my Toes, but Meiosis is in my Ovaries

  23. Number of Chromosomes Why Meiosis? • Fertilization • Union of sperm and egg (n) • Zygote is formed (2n) • The chromosome number is reduced, so at fertilization there is the correct # of chromosomes.

  24. Why meiosis? • Cuts chromosome # in half • Creates variation for Evolution • Makes offspring unique

  25. 1) Law of Segregation chromosome pairs separate during meiosis 2) Law of independentassortmentgenes are separated randomly (shuffle) 3) Crossing Over chromosome parts break off & reattach to other chromosomes creates new chromosome Meiosis creates variation in 3 ways

  26. both new cells are identical to the original (all cells except sperm & eggs do this) Mitosis(1 cell becomes 2)

  27. In Meiosis… 1 cell becomes 4 cells called gametes Male gametes = Sperm Female gametes = Eggs Mitosis is in my Toes, but Meiosis is in my Ovaries

  28. Diploid (2N) Cells with 2 full sets of genetic info Human body cells have 46 chromosomes each (diploid or 2N # is 46) Haploid (N) Cells with 1 set of genetic info Human sperm & eggs have 23 chromosomes (haploid or N # is 23) Mitosis or Meiosis

  29. Mitosis Makes diploid cells All cells identical Involved in somatic cell reproduction. Happens ALL your life Meiosis Makes haploid cells Makes genetically different cells Takes place at certain times Males: after puberty Females: Before birth Why ---Importance:

  30. Stages of Meiosis Interphase Prophase I Metaphase I Anaphase I Telophase I Prophase II Metaphase II Anaphase II Telophase II

  31. Interphase Interphase is the same as Mitosis. G1, S phase and G2.

  32. Prophase I Same as Mitosis…except: Each pair of sister chromosomes matches with another set of sister chromosomes. Forms a tetrad- 2 sets of chromosomes (4 chromatids). • This step is when crossing over occurs!!!!

  33. Metaphase I The tetrads line up at the center of the cell.

  34. Anaphase I Tetrads separate into chromosomes and move to opposite ends of the cell.

  35. Telophase I The chromosomes uncoil and the cell begins to break into two cells. Still too many chromosomes, so the cells goes through another 4 stages.

  36. STOP!! • There is NO interphase II in meiosis… • Why?? • No need to replicate the DNA again…. We’re making haploid cells with only HALF the required DNA.

  37. Prophase II Chromosomes coil and thicken. Nuclear envelopes break down.

  38. Metaphase II Chromosomes line up at the center of the cell.

  39. Anaphase II Chromosomes separate and the chromatids move to opposite ends of the cell.

  40. Telophase II The chromatids uncoil and lengthen, and the cell breaks into two cells. Four gametes have been made They are haploid cells (half necessary DNA).

  41. Meiosis • Interphase (approx 90% of time) • DNA Replication • Prophase 1 Tetrad forms • Crossing over occurs • Metaphase 1 • Chromosomes move to midline • Anaphase 1 • Homologous chromosomes separate • Anaphase 2 • Sister chromatids separate The Rest is Just Like Mitosis!

  42. Chromosomes • How do we look at the chromosomes of an individual? • The collection of chromosomes found in an individual’s cells Karyotype

  43. Chromosomes • How is it made? • Chemically treat and stain chromosomes in cells from a blood sample • The chromosomes are then photographed, cut out, arranged in pairs from largest to smallest, and numbered

  44. Chromatin Chromosome Scatter Karyotype

  45. Chromosomes Abnormalities • Nondisjunction (NOT-COMING-APART) Chromosomes fail to separate during anaphase 2. Mutations:changes in Chromosome Structure

  46. Nodisjunctions • What if a chromosome is missing? • Most do not survive to be born • If a chromosome is missing the condition is called Monosomy • EX: Turners (XO)

  47. Nondisjunctions • What if a cell has an extra chromosome? • The condition in which a cell has an extra chromosome is calledTrisomy • Example: Trisomy 21 (Down Syndrome)

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