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Chapter 12 Notes

Chapter 12 Notes. Mitosis & Cell Cycle. Introduction. Genome – entire set of genetic information Genetic information = DNA DNA is organized into chromosomes Chromosomes = DNA + Histone proteins Diploid – 2 sets of chromosomes Haploid – 1 set of chromosomes

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Chapter 12 Notes

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  1. Chapter 12 Notes Mitosis & Cell Cycle

  2. Introduction • Genome – entire set of genetic information • Genetic information = DNA • DNA is organized into chromosomes • Chromosomes = DNA + Histone proteins • Diploid – 2 sets of chromosomes • Haploid – 1 set of chromosomes • Half the number of chromosomes as diploid

  3. Transcriptome & Proteome • 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 • DNA  RNA  Protein • Genome Transcriptome Proteome

  4. Vocabulary • Cell Cycle – life of a cell from formation until division or death • Mitosis vs. Meiosis • Every somatic (Body) cell is a clone of the zygote • BUT the zygote is formed from union of cells • Each of which was produced by Meiosis (gametes) • Only cells that are not clones are gametes • Male = sperm Female = egg cells

  5. Questions • Which cells arose from Mitosis? (Diploid) • All cells except gametes • Called somatic cells • Which cells arose from Meiosis? (Haploid) • Only sperm in males (spermatogonia) • Only egg cells in (oogonia) • Called gametes

  6. Cell Cycle

  7. Cell Cycle Notes • 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

  8. Mitosis

  9. Mitosis Notes by chromosomes • Interphase (G2) = 2x DNA as usual • Call it 92 DNA units (2*46 = 92 = Chromosomes) • Prophase/Metaphase = 2x DNA as usual • BUT same number of chromosomes • Each chromosome = 2 chromatids • Chromatids are copies of each chromosome • Chromosomes = 92 DNA units • 2 sets of Chromatids = 2 *46 = 92 DNA units

  10. Mitosis Notes (Page 2) • Anaphase/Telophase = 1x DNA as usual • Chromatids separate • Now the chromatids are called “Daughter chromosomes” • Each cell has ½ the DNA units • ½ of 92 DNA units (Metaphase) = 46 DNA units • So each daughter cell has 46 DNA units • Each parent cell has 46 DNA units

  11. Chromatin, Chromatids, & Chromosomes • Chromatin – diffuse form of DNA + Protein • Chromosomes – condensed form of DNA + Protein • Chromatids – 2 chromatids are attached at the centromere • 2 copies of the same chromosome • Each chromatid Daughter chromosome at Anaphase

  12. Cell Cycle Regulation • Cell cycle control system • 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

  13. Checkpoints • Control points of cell cycle • Cell cycle is controlled by a series of checkpoints • Tell cell to stop or go through cellular division • G1 phase checkpoint • G2 phase checkpoint • M phase checkpoint

  14. G1 Checkpoint “Restriction” • Most important checkpoint in mammalian cells • If G1 is successful, then G1, S, G2, and M go ahead • If NOT, then G0 stage • G0 is called the nondividing stage • Independent of cell cycle • Most cells in the body are in G0

  15. Protein kinases & Cyclins • Regulatory molecules for cell cycle • What do protein kinases do? • Protein kinases give the “Go ahead” signal @ G1 & G2 checkpoints • Most protein kinases are inactive • Activated by cyclins (cyclical fluctuating protein) • Called cyclin-dependent kinases(Cdk)

  16. Maturation Promoting Factor (MPF) • Example of a Cdk + cyclin interaction • Signal that allows cell to pass through G2 into mitosis • Can be thought of as “Mitosis Promoting Factor”

  17. Normal cells… • Density Dependent Inhibition • Crowded cells cease mitosis • Binding of a cell surface protein to its counterpart on an adjoining cell = growth-inhibiting signal for both cells • Anchorage Dependency • In order to divide, cells must be attached to a substratum • Substratum = ECM or other load-bearing material

  18. 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

  19. It’s not a tumor… • Tumor = mass of abnormal cells • Abnormal because? • Benign tumor – abnormal cells that remain at the original site • Malignant tumor – abnormal cells impair functions of one or more organs

  20. Cancer = malignant neoplasm (tumor) • Malignant tumors are characterized by anaplasia, invasiveness, & metastasis • Anaplasia – reversion of differentiation • Invasiveness – Intrusion into and destruction of surrounding tissues • Metastasis – spread of neoplasms via blood vessels to distant tissues or organs

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