BOLOGY 107 1st Edition Lecture 18Outline of Last Lecture I. Anaerobic Respiration and Fermentationa. Processb. Lactic acid fermentationc. Alcohol fermentationII. Cell divisiona. Mitosis, meiosis, and cytokinesisb. Cell cyclec. Mitosis i. Chromosomes Outline of Current Lecture III. ChromosomesIV. Mitosisa. Structures formedb. Stages c. Alternatives Current LectureChromosomes1) When forming sister chromatid (copies), they become visible as separatea) During the S phase2) Structures a) Centromere i) Constructed where the sister chromatid attachb) Kinetochorei) proteins around the centomere, where microtubules will attachMitosis3) Structures formeda) Mitotic spindlei) Assemble at centromeres, formed of microtubules and associated proteins(1) Asters- connect the centromeres to the cell membrane(2) Kinetochore microtubules- connect to the kinetochores of the chromosomesThese 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.(3) Overlapping microtubules- connect to each other in middle of cell4) Stages a) Interphase (preparation)i) Nuclear envelope is present around chromosomesii) Chromosomes are not distinct, one balliii) G2(1) Chromosomes are duplicated(2) Centrosomes are duplicatedb) Prophasei) Chromosomes become distinct as they condenseii) Centrosomes move to opposite ends of the celliii) Spindle formsc) Prometaphase i) Nuclear envelope breaksii) Spindle is completed) Metaphase i) Centrosomes are at opposite ends of the cellii) Chromosomes align at metaphase plate (equidistant from each centrosome)iii) Cell does not continue until chromosomes are aligned, called the M phase checkpointe) Anaphase i) Anaphase A(1) Proteins holding chromatids together disintegrate (2) One of each set of sister chromatids move towards a centromere by depolarizing the microtubule and cutting it(3) Now considered daughter chromosomesii) Anaphase B(1) Spindle poles move apart, cell elongatesf) Telophase i) Chromosomes arrive at the polesii) Nuclear envelopes form around each bunch of chromosomesiii) Chromosomes de-condenseiv) Cytokinesis occursg) Interphase occurs with new cellsh) Plants are constricted by cell walls and have no centrioles5) Alternatives to mitosis (mitochondria and plastids)a) Prokaryotes go through binary fissionb) Protists and some yeastsi) Dinoflagellates have no spindle and the nuclear envelope does not breakdownii) Diatoms and some yeasts form the spindle in the nuclear
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