• Ch 9 Cell Division • G1 stage growth

							General Biology Lecture Outline
Lecture 14                                                    – Determine if cycle continues
Overview: Cell Division                                       – Damage leads to apoptosis
•   Ch. 9: Cell Division                                           • Programmed cell death
    –   Cell cycle                                                 • Caused by caspases (enzymes)
    –   Mitosis                                           Cell Cycle Checkpoints
    –   Cancer                                            • G1 checkpoint
    –   Prokaryotic cell                                  • G2 checkpoint
        division                                          • M checkpoint
The Cell Cycle: Interphase                                The G1 Checkpoint
•   G1 stage: growth                                      • Evaluates growth signals
•   S stage: DNA replication                                 – CDK adds P to RB
                                                             – E2F released
•   G2 stage: preparation for division
                                                             – Activates genes that complete cell cycle
Assignment 1                                              • Determines nutrient availability
•   Think, Pair, Share                                       – G0: P removed from RB if nutrients low
•   Topic: Many cells (such as brain cells) go into          – G1: P added to RB if nutrients available
    a stage when they no longer divide.                   • Assesses DNA integrity
    – What are those cells doing if they are not              –   CDK adds P to p53 if DNA damaged
        dividing?                                             –   P -p53 binds to DNA
    – Why do skin cells divide frequently when                –   DNA repair proteins produced
        other types of cells do not?                          –   Apoptosis if not fixed
The Cell Cycle: Mitosis                                   Assignment 3
•   M stage                                               •   Think, Pair, Share
    – Prophase                                            •   Topic: What problems would you expect to
    – Metaphase                                               occur in a cell with a non-functional p53
                                                              protein?
    – Anaphase
    – Telophase                                           Chromosomes in Eukaryotes

Assignment 2                                              •   Chromatin

•   Think, Pair, Share                                    •   Chromosome

•   What are the four stages of the cell cycle?
                                                              – Sister
                                                                  chromatids
    – During which of these stages is the DNA
      replicated?
                                                              – Centromere
    – When does cell division occur?                          – Kinetochores
Control of the Cell Cycle                                 •   Histones
                                                               – Bind to DNA
•   Growth factors
                                                               – Nucleosome
    – Signaling proteins
                                                          Chromosome Number
    – Stimulate cell to complete cell cycle
•   Cell cycle checkpoints
                                                          •   Total chromosomes in a cell

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General Biology Lecture Outline

    – Karyotype                                             – Metaphase plate
Chromosome Number                                       Anaphase
• Somatic cells                                         • Sister chromatids pulled apart
    – Diploid (2n)                                          – Chromatids are now daughter
    – Humans: 2n = 46                                         chromosomes
    – By mitosis                                        • Daughter chromosomes now move towards
• Gametes                                                   opposite poles
    – Haploid (n)                                       Telophase
    – Humans: n = 23                                    •   Chromosomes decondense
    – By meiosis
                                                        •   Two nuclear envelopes form
The Mitotic Spindle
                                                        Results of Mitosis
• Moves chromosomes during mitosis
• Organized by centrosome
                                                        •   2 daughter nuclei
    – Contains centrioles in animals                        – Each with parental chromosome #
• Microtubules: 2 sets                                      – Chromatin unduplicated
    – From cell poles                                   Assignment 4
    – Overlap at spindle equator                        •   Think, Pair, Share
Mitosis                                                 •   What are the 4 main phases of mitosis?
•   Nuclear division     cytoplasmic division               – During which phase do sister chromatids
•   Four stages:                                               separate?
    –   Prophase                                            – During which phase do chromosomes
                                                               condense?
    –   Metaphase
                                                            – During which phase are chromosomes
    –   Anaphase                                               aligned at the spindle equator?
    –   Telophase
                                                        Cytokinesis
Early Prophase – Mitosis Begins                         • Between late anaphase to end of telophase
•   Duplicated chromosomes condense                     • 2 mechanisms
•   Nuclear envelope fragments                              – Cleavage (animals)
Prophase                                                    – Cell plate formation (plants)
                                                        Stem Cells
•   Centrosomes move to opposite poles
     – Spindle microtubules form                        • Reproductive cloning
                                                            – Produce new individual
    – Asters
                                                        • Therapeutic cloning
Prometaphase                                                – Produce human tissues
•   Spindle microtubules attach to kinetochore on       Mitotic Cell Division
    each chromatid
                                                        •   High accuracy
Metaphase
                                                        •   Occasional mistakes
•   All chromosomes line up at the spindle
    equator                                                 – Benign tumors

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General Biology Lecture Outline

    – Malignant tumors                                •   Topic: Based on what you know about the
Cancer Cells                                              complexity of prokaryotic cells & eukaryotic
                                                          cells, which should be simpler to divide?
•   Lack differentiation
                                                          – How might complexity affect the rate of
•   Have abnormal nuclei                                     division?
•   Do not undergo apoptosis
                                                      Prokaryotic Cell Division
•   Form tumors
                                                      • Attachment of chromosome to plasma
•   Undergo metastasis & angiogenesis                     membrane
     – Invade tissues                                 •   Cell enlarged
     – New blood vessels into tumor
                                                      •   DNA replication
Cancer
                                                      •   Chromosomes pulled apart
•   Mutations of two types of genes                   •   Cell wall & plasma membrane divides into
    – Proto-oncogenes                                     daughter cells
         • Normally promote the cell cycle &          Cell Division
           prevent apoptosis when stimulated
           (e.g., injury)                             • Mitosis & cytokinesis
         • May become oncogenes (cancer-                  – Development, growth, & repair of
           causing genes)                                   eukaryotes (multicellular)
                                                          – Asexual reproduction of eukaryotes
    – Tumor suppressor genes                                (unicellular)
         • Normally inhibit the cell cycle &
           promote apoptosis                          • Binary fission
         • May become inactive (e.g., RB & p53)           – Asexual reproduction of prokaryotes
                                                      Reminders
•   Mutations of DNA repair system
•   Mutations maintaining telomere length
                                                      •   Next Week’s Lab:
                                                           – Lab 9: Mitosis & Meiosis
Assignment 5
                                                              • Turn in Lab 8 at the beginning of your
•   Think, Pair, Share                                          lab time
•   Topic: Why is it necessary to have proto-         •   From Today
    oncogenes that normally promote the cell              – Study Ch. 9 of the textbook
    cycle & prevent apoptosis?
                                                             • Read! Study figures! Learn terms!
    – How do oncogenes differ from proto-                    • Review with textbook questions for this
       oncogenes?                                              chapter
Prokaryotic Cell Division                                    • Review with the online activities
•   Prokaryotic organisms                                 – Tuesday, October 27th: EXAM 3 (Ch. 6 –
     – Single, circular chromosome                          8)
        • Nucleoid                                           • Parscore scantron, RCC ID, pencil,
                                                               eraser
    – Binary fission
         • A form of asexual reproduction
Assignment 6
•   Think, Pair, Share


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