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Cell Cycle, Mitosis, & Regulation

Cell Cycle, Mitosis, & Regulation. Chapter 12. Genome. Kinetochore – protein attaches to chromosome at centromere + attaches to mitotic spindle. Haploid –Set of unique chromosomes  Only in gametes  Sperm + Egg Diploid – 2 sets of the unique chromosomes  1 set from Mom

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Cell Cycle, Mitosis, & Regulation

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  1. Cell Cycle, Mitosis, & Regulation Chapter 12

  2. Genome

  3. Kinetochore – protein attaches to chromosome at centromere + attaches to mitotic spindle

  4. Haploid –Set of unique chromosomes •  Only in gametes •  Sperm + Egg • Diploid – 2 sets of the unique chromosomes •  1 set from Mom •  1 set from Dad • ALL cells but gametes • Somatic Cells 2,700 base pairs OR 2.7 kbp (MIT – D. Gifford [7.90J]) What percent of chromosomal DNA = genes?

  5. “-omes” • Genome – Complete set of genetic information • Transcriptome – set of all the mRNA produced by a cell or an organism • Proteome – entire set of proteins coded for by the genome of a cell or an organism • How many chromosomes in human genome? • Which is larger, genome or transcriptome?

  6. Central Dogma of Molecular Biology • DNA  RNA  Protein • HIV (Reverse Transcriptase) • cDNA (Complementary DNA library) • Prions – infectious proteins • Genome  Transcriptome  Proteome

  7. Divisions • Prokaryotes = binary fission • Eukaryotes • Mitosis • ALL cells arise by mitosis EXCEPT zygote (original cell) • Meiosis • ONLY used to produce egg (oocyte) and sperm (spermatocytes)

  8. This is NOT mitosis!!  Proks do NOT do mitosis

  9. Mitosis • Occurs in which type of cells? • Occurs where in the body? • Genetically identical (Clone) • Produces diploid daughter cells • Produces clones • Somatic cells

  10. Meiosis • Occurs in which type of cells? • Occurs where in the body? • Genetically different • Produces haploid daughter cells • Produces eggs or sperm • Produces Gametes

  11. Questions? • Which is more common mitosis or meiosis? • What is the main way that prokaryote chromosomes differ eukaryotic chromosomes? • Binary fission or mitosis? • Fungi • E. Coli • Plants • What percent of DNA is non-coding in humans?

  12. Questions? (Page 2) • What is the genome? • What is larger proteome or genome? • Haploid or Diploid? • Red Blood Cell • Muscle Cell • Sperm • Neuron • Macrophage • CD4 T-Cell

  13. Cell Cycle  “Life of a cell”  From time it is first formed until it divides into 2 daughter cells

  14. Notes on Cell Cycle • G1 – Cell growth • Cells do their cell things • Vast majority of time in the cell cycle • Human cell = 46 chromosomes • S – Chromosomal duplication • Human cell = 46*2 = 92 chromosomes • Cells still grow during this time • G2 – Second Gap • Brief period between S and Mitosis • Mitosis / Cytokinesis

  15. Watch Videos • Overview.swf • Mitosis.mpg • The_Stages_of_Mitosis_HD.mp4

  16. Cytokinesis • Cytokinesis – Cytoplasmic (and contents) division • Cytokinesis Video? • During telophase  G1 • Animal cells • Cleavage furrow divides the cytoplasm into 2 cells • Plant cells • Cell plate forms that divides the cytoplasm

  17. Cell Cycle Control • Some cells divide • Continuously (skin cells) • Occasionally (liver cells) • Never (CNS cells & muscle cells) • Signals to divide are present in cytoplasm • These signals control the rate of cell division • Result of signal transduction pathways

  18. Cell Cycle Regulation • Involves checkpoints • There are 3 checkpoints: G1, G2, and M • G1 checkpoint - Most important • G0 – nondividing phase • Most body cells • Neurons & Muscle cells

  19. Kinase – protein enzymes that control cell cycle Cyclins – proteins that bind to kinases and activate them CdK – cyclin-dependent kinase  Activated kinases  give the Go-ahead signal at the checkpoints

  20. Questions? • What are the phases of the cell cycle? • What are the parts of interphase? • What are the parts of mitosis? • What happens during the S-phase?

  21. Questions (Page 2) • What is a CdK? • What is the G0 phase? • How is cytokinesis different in animal cells from plant cells? • When does cytokinesis occur in the cell cycle? • How does a kinetochore differ from a centromere?

  22. Normal Cells  Controlled cell cycle  Density-dependent Inhibition - Too many cells = no division - Once a cell contacts another cell, division ceases - Contact Inhibition  Anchorage Dependence - Division only happens when cell is attached to a substrate - If attached to another cell, no division

  23. Cancerous Cells • Do NOT adhere to normal cell signals • Divide excessively • Violate density-dependent inhibition & anchorage dependency • Considered “immortal cells” • Normal cells undergo a process of genetic alteration that affects cell cycle regulation • Called Transformation

  24. Tumor Terms • Tumor = mass of abnormal cells • Abnormal because? • Benign tumor • abnormal cells that remain at the original site • Malignant tumor • abnormal cells that impair functions of one or more organs

  25. Cancer is characterized by … • Malignant tumors are characterized by anaplasia, invasiveness, & metastasis • Anaplasia • Cells do not undergo differentiation • Invasiveness • Intrusion of cells into and destruction of surrounding tissues • Metastasis • Spread of neoplasms via blood vessels to distant tissues or organs

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