BOLOGY 107 Lecture 19 Outline of Last Lecture I Chromosomes II Mitosis a Structures formed b Stages c Alternatives Outline of Current Lecture III Cytokinesis IV Cell Cycle Control V Meiosis Current Lecture Cytokinesis 1 Division of two cell bodies 2 Animals a Actin forms contractile fibers around the cell myosin contracts the actin until the cell is cut in half 3 Plants a Vesicles containing the components of the cell wall move to the center and fuse to form new wall Cell Cycle Control 4 Checkpoints a G1checkpoint i Decides if the cell continues through the cell cycle goes into stasis or is differentiated 1 Decision is based on if there are enough materials for the cell to continue on and if the cell is needed for division b G2 checkpoint i Another check to see if there are enough materials to continue the cycle c M checkpoint i A stasis until the chromosomes reach the metaphase plate d The checkpoints are triggered by alterations in regulatory proteins i Balance between stimulators and repressors These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute e Cancer i Failure of appropriate cell control 1 Transformation loss of contact inhibition immortalization ii Benign cancer uncontrolled growth in a localized area iii Malignant cancer cancer cells enter circulation spread and attach around the body 1 Metastasis new tumor formed from this process Meiosis f Homologous chromosomes same set of chromosomes one from each parent 5 Two constructive nuclear divisions a Create gametes haploid n b Used in reproduction only when fertilized create a zygote c Chromosomes duplicate in S phase d Meiosis I similar to mitosis steps differences listed i Prophase I 1 Physical pairing of homologous chromosomes 2 Crossing over extra contact points switch DNA and form chiasmata ii Metaphase I 1 Same as in mitosis iii Anaphase I 1 Chromosomes assort randomly and separate in their chromatid pairs iv Telophase I 1 Chromosomes don t de condense v Two cells formed e Meiosis II i The two cells undergo the same steps just as mitosis no changes other than that the chromosomes are already duplicated ii The chromatid pairs separate iii Results in four daughter cells each haploid
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