BIOL 111 301 1st Edition Lecture 6Outline of Last Lecture I. Cell MembranesII. DiffusionIII. OsmosisIV. AquaporinV. Movement across membraneOutline of Current LectureI. Cell Division and the cell cycleII. Stages of mitosis III. CytokinesisIV. Control of CellV. Cancer: unstoppable cell division Current Lecture- Cell division and the cell cycleo Why do cells need to divide? To have the embryo to grow bigger, to replace the lining in your gut, wound repairo Where do cells divide?o What is the end result of cell division? DNA replication Cell growth Two daughter cellso Prokaryotes—Binary fissiono Eukaryotes (have a nucleus)—mitosis and cytokinesis Dividing the nucleus into two-mitosis Dividing the rest of the cell into two-cytokinesiso Vocabulary Chromatin-DNA + protein Chromosome-Discrete unit of DNA + protein Chromatid-Replicated chromosome attached Centromere-Portion of chromosome that connects chromatids Centrosome-Region that organizes the centrioles and other microtubules Kinetochore-Protiens at centromere that interact with spindle microtubuleso Are all cells dividing? G0 In dividing cells:- Interphase: G1 (make more nucleotides), S (synthesis of DNA), G2 (making spindle apparatus) Mitotic phase- Mitosis - Cytokinesis - Stages of mitosiso G2 of interphase Centrosomes (with centriole pairs) Chromatin (duplicated)o Prophase Early mitotic spindle Aster Chromosome, consisting of two sister chromatidso Prometaphase Fragments of nuclear envelope No kinetochore microtubuleso Metaphase All chromosomes aligned on the metaphase plate Centrosome at one spindle pole o Anaphase Sister chromatids splito Telophase and cytokinesis Nuclear envelope forming Nucleolus forming Cleavage furrow- Cytokinesis: division of the cytoplasmo Animal cells: Cleavage furrow Microfilaments (actin) and myosino Plant cells: Cell plate-cell wall + plasma membrane Vesicles derived from Golgi- Control of the cell cycleo Checkpoints (border crossings) Need some sort of signal to signal to the border crossing that you can keep going o Signals Accumulation of specific protiens (cyclins) G2 checkpoint- Cyclin protein accumulates- Interacts with Cdk enzyme- Forms mitosis promoting factor- Mitosis indicated- Cancer: uncontrolled cell divisiono No checkpointso Non-stop mitosis creates tumorso No density dependent inhibitiono Tumors can spread to other parts of
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