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Similar to 1406 ch 8 DNA replication mitosis
1406 ch 8 DNA replication mitosis
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- 2. Learning objectives forDNA replication, cell cycle, and mitosis • Explain how cells divide to give rise to identical cells • Describe the steps of replication and the function of enzymes in each step including: • helicases • RNA polymerase • DNA polymerase • ligases • Explain what features of DNA allow semiconservative replication to occur • Describe the steps that occur as a chromosome folds into chromatin • Explain what is happening in a cell at each stage of the cell cycle • Diagram and identify the phases in mitosis • Explain what is meant by a checkpoint and how these relate to cancer • Compare and contrast the role of an oncogene and tumor suppressor in cancer • Compare and contrast the growth of a normal cell and a stem cell
- 3. Cells Divide andCells Die
- 4. 1 day 2–3days 4 days 7 days 13 days 21 days 26 days 28 days 32 days 33 days 37 days 41 days 44 days 47 days 50 days 52 days 54 days 56 days LM 50 μm LM 50 μm LM 50 μm 50 μm 50 μm 80 μm 1 mm 2 mm 5 mm 5 mm 5 mm 5 mm 5 mm 5 mm 5 mm 5 mm 5 mm 5 mm 5 mm
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- 6. MITOSIS MITOSIS FERTILIZATION MEIOSIS MEIOSIS Gametes (sperm andegg cells) Figure 8.1 Zygote (fertilized egg)
- 8. DNA replication proteins Helicase unwinds double helix. Binding proteins stabilize each strand. Primase adds short RNA primerto template strand. DNA polymerase binds nucleotides to form new strands. Ligase creates covalent bond between adjacent DNA segments.
- 9. DNA polymerase addsDNA nucleotides to the RNA primer. Proofreading activity checks and replaces incorrect bases just added. Leading (continuous) strand synthesis continues in a 5′ to 3′ direction. Helicase separates strands. Binding proteins prevent single strands from rejoining. Primase makes a short stretch of RNA on the DNA template. Overall direction of replication Discontinuous synthesis of the lagging strand produces Okazaki fragments. After RNA primer is replaced with DNA, ligase seals the sugar–phosphate backbone. Steps in DNA replication RNA primers New DNA strands Okazaki fragment Leading strand Lagging strand Figure 8.5 contd. 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 3’ 5’ 5’ 5’ 5’ 5’ 5’ 5’ 5’ 5’ 5’ 5’ 5’ 5’5’ 5’ 5’ 5’5’
- 10. Figure 8.6 Origins ofreplication Original DNA molecule Daughter strands Parental strands Two identical DNA molecules Parental strands Daughter strands
- 11. Cell membrane DNA Cell wall Parentcell contains one chromosome. DNA replicates and attaches to cell membrane. Membrane growth between the two attachment points moves the DNA molecules apart as new cell wall material is deposited. The result of binary fission: two daughter cells, each identical to the original. Prokaryotes - Binary Fission
- 12. Naked DNA (all histones removed) Nucleosome Histones Scaffold protein Centromere Identical sister chromatids Replicated chromosome Moderately compacted chromatin Highlycompacted chromatin NucleusCell Loosely packed chromatin Eukaryotes - Chromosomes condense
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- 14. Figure 8.10 G1 phase (normalcell function and cell growth) S phase (DNA replication) G2 phase (additional growth and preparation for division) G0 phase (nondividing) The Cell Cycle
- 15. Interphase • G1 • G0 •S • G2
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- 18. Figure 8.11 ANAPHASE TELOPHASECYTOKINESIS G1, EARLY INTERPHASE Centromeres split as sister chromatids separate and move to opposite poles of cell. Nuclear envelope and nucleolus form at each pole. Chromosomes decondense. Spindle disappears. Division of the cytoplasm into two cells. Cells resume normal functions or enter another division cycle. Contractile ring LM 20 µm LM 20 µm LM 20 µm LM 10 µmLM 10 µm LM 10 µm (all animal): ©Ed Reschke/Photolibrary/Getty Images; (all plant): ©Ed Reschke
- 19. Contractile ring Cleavage furrow Cleavage furrow Cytokinesis in progressCytokinesis complete TEM (false color) 10 µm Cell plate composed of vesicles Cell wall Cytokinesis in progress Microtubules LM 25 µm Cytokinesis complete Two cell walls Figure 8.12 Nucleus NucleusCell plate
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- 21. G2 checkpoint • Hasall DNA replicated? • Can damaged DNA be repaired? • Is spindle-making machinery in place? Metaphase checkpoint • Do kinetochores attach to spindle? • Are chromosomes aligned down equator? S phase checkpoint • Is DNA replicating correctly? S phase (DNA replication) G2 phase (additional growth and preparation for division) G1 phase (normal cell function and cell growth) G1 checkpoint • Is DNA damaged? G0 phase (nondividing) Regulation of Cell Division Growth Factors Checkpoints
- 23. Malignant cells can"seed" new tumors throughout the body. Blood vessel Malignant tumor Benign tumor Capsule of connective tissue keeps tumor from spreading. Lymph vessel Lymph vessel a. Benign tumor b. Malignant tumor Metastasis Blood vesselsNew tumor New tumor Lymph vessel Capsule
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- 29. Figure 8.16 Proto-oncogene Tumorsuppressor gene Mutated or silenced proteins block cancer development. Proteins absent or fail to block cancer Development. proteins accelerate cell cycle. Normal Normal proteins stimulate cell division. Oncogene Cancer cells No CancerNormal cells Mutated or overly activeNormal Normal cell
- 31. Figure 8.18 To avoidor reduce the risk of cancer Eat a healthy diet, low in saturated fat and rich in fruits and vegetables Avoid UV radiation from sunlight and tanning beds. Stop using tobacco, or better yet, never start. Use self tests and medical exams for early detection. Use condoms to avoid exposure to viruses known to cause cancer. Get regular vigorous exercise. Avoid obesity:
- 32. Term Definition Chromatin Cleavage furrow ChromosomeA single, continuous molecule of DNA wrapped around protein. Eukaryotic cells contain multiple linear chromosomes, whereas bacterial cells typically have one circular chromosome. Collective term for all of the DNA and associated proteins in a cell Chromatid One of two identical attached copies that make up a replicated chromosome Centromere A small part of a chromosome where sister chromatids attach to each other Interphase Stage of the cell cycle in which chromosomes replicate and the cell grows G1 phase G0 phase G2 phase S phase Gap stage of interphase in which the cell grows and carries out its functions Gap stage of interphase in which the cell functions but does not divide Gap stage of interphase in which the cell produces membrane components and spindle proteins Synthesis stage of interphase when DNA replicates Mitosis Prophase Prometaphase Metaphase Anaphase Telophase Cytokinesis Cell plate Centrosome Spindle Kinetochore Protein complex to which the spindle fibers attach on a chromosome’s centromere Array of microtubule proteins that move chromosomes during mitosis Structure that organizes the microtubules that make up the spindle in animal cells Material that forms the beginnings of the cell wall in a plant cell undergoing cytokinesis Indentation in cell membrane of an animal cell undergoing cytokinesis Distribution of cytoplasm to daughter cells following division of a cell’s chromosomes Stage of mitosis when chromosomes arrive at opposite poles and nuclear envelopes form (telo- = end) Stage of mitosis when the spindle pulls sister chromatids toward opposite poles of the cell Stage of mitosis when chromosomes line up along the center of the cell (meta- = middle) Stage of mitosis when the nuclear membrane breaks up and spindle fibers attach to kinetochores Stage of mitosis when chromosomes condense and the spindle begins to form (pro- = before) Division of a cell’s chromosomes into two identical nuclei Table 8.1