Biology 1113 Week 8 Notes
Biology 1113 Week 8 Notes Bio1113
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This 4 page Class Notes was uploaded by Jessy Notetaker on Monday October 10, 2016. The Class Notes belongs to Bio1113 at Ohio State University taught by Dr. Larson in Fall. Since its upload, it has received 8 views. For similar materials see Biology in Biology at Ohio State University.
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Date Created: 10/10/16
Week 8 Notes Mitosis Cell theory: all cells come from other cells Reasons why cells divide Asexual reproduction Growth and development Tissue renewal Standard maintenance Maintain a surface area to volume ratio When a cell reaches a certain limit, it will either stop growing or divide Types of cellular division Sexual division We will talk about this next week Asexual reproduction Mitosis Binary fission DNA We have lots of it Genome The DNA of a cell Prokaryotes Single circular chromosome Makes reproduction easy Eukaryotes Linear chromosomes Cells often contain 2 copies of each chromosome Homologous chromosomes Chromosomes Composed of chromatin DNA + histones (proteins) DNA is wrapped around histones like a spool of thread Structure Centromere- condensed region of the chromosome The middle where it pinches together Telomere- a region of repetitive DNA sequences at the end of chromosomes Does not code for anything Protect the real DNA from being chopped off Kinetochore- disc-shaped protein that spindle fibers attach to Chromatid 2 chromatids make a chromosome Exact copy of each other Chromosomes are duplicated before division When the cell divides, the chromosomes are pulled apart, making 2 copies of a cell Binary fission Form of asexual reproduction Used by bacteria One circular chromosome Super-fast process Process DNA replicates DNA is pulled to the ends of the cell Cell wall and plasma membrane divide Wall and membranes completely form and cell divides Mitosis Eukaryotic cycle G1 Gap 1 Cell is growing Protein synthesis Organelle synthesis S DNA is replicated G2 Growth Synthesis of microtubules Makes sure there is enough mass to sustain 2 cells Cell cycle checkpoints G0 Metabolically active Majority of the cells in the human body are here Not actively reproducing Cells spend 90% of their time on interphase Nuclear division Divides the DNA into 2 equal sets Cytokinesis- division of organelles and cytoplasm 5 phases Prophase DNA condenses into chromosomes Nuclear envelope is disassembled Prometaphase Microtubules connect to the kinetochores Metaphase Chromosomes are lined up in the center of the cell Anaphase Chromatids are pulled apart Protein that held them together gets cut Telophase and cytokinesis Telophase Nuclear envelope starts to reassemble DNA uncoils into chromatins Cytokinesis Actual division Animal cells Membrane pinches in Makes a cleavage furrow Plant cells New cell wall is formed Golgi makes the building materials to the wall Cell cycle regulation Tight regulation is crucial for normal growth and development Controlled by a system of signaling molecules which trigger and coordinate events Multiple checkpoints make sure the cells is ready to go on to the next step G1 oing into S Restriction point Most important in mammals If cell receives: Green light- continues to S phase Red light- exits cell cycle, enters 0 Cell can be repaired and return to the cycle, or undergo apoptosis Is the cell big enough? Are conditions favorable? Is the DNA damaged? 2 main regulatory molecules Cyclins Levels fluctuate cyclically Peak during mitosis Cyclin-dependent kinase Enzyme with a phosphate Function requires a cyclin Also peaks during mitosis G2 heckpoint Maturation-promotion factor (MPF) Uses cyclin-dependent kinases Targets include: Condensins Condenses the chromosomes Proteins involved in mitotic spindle formation Lamins Proteins involved in nuclear envelope breakdown/assembly Anaphase promoting complex (APC) Metaphase to anaphase checkpoint Ensures that there is a microtubule attached to each side of the chromosomes Tophat questions When the chromosome looks like an S, what phases could the cell be in? Metaphase or prophase Compared to the other phases, how much DNA is in a cell during metaphase? Metaphase contains twice the amount of DNA because replication has occurred, but has not split yet