bio test 4 notes - Cell Cycle/Mitosis Cell Cycle The life...

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Cell Cycle/Mitosis Cell Cycle The life of a cell Cell begins when you divide a cell into 2 new ones End of the cell is when that cell divides Cytokinesis The end of cell division Division of cytoplasm, when 1 cell becomes 2 Stages in cell cycle Interphase G1: Gap 1 S: synthesis, synthesis of DNA so in reality it is replication, rate you make or copy DNA G2: Gap 2 Mitotic phase Mitosis A type of division of nucleus Cytokinesis A division of cytoplasm Cell division Chromosome structure DNA and Histone Proteins During interphase Relaxed Extended During Cell Division Supercoiled Condensed They exist in 2 forms Chromosomes can be un-replicated 1 molecule of DNA Chromosomes can be replicated 2 identical molecules of DNA, held together Whether replicated or not its always 1 chromosomes even though you might have 2 molecules of DNA
coming out of cytokinesis at the start or beginning of a cell your chromosome is un- replicated, it consist of 1 DNA molecule and they stay that way through G1 and when you start the S phase you only have 1 chromosome and at the end of S there are 2 molecules of DNA and 1 replicated chromosome and then you start the mitotic phase with a replicated chromosome and you end the mitotic phase with un-replicated chromosomes Mitosis Cell Reproduction Two Steps Division of nucleus: Karyokinesis Mitosis Meiosis Division of cytoplasm: Cytokinesis Sometimes the cell will divide its nucleus but not always the cytoplasm so you will end up with a cell that has multiple nuclei Chromosomes Structure Chromosomes can be un-replicated 1 molecule of DNA chromosome can be replicated 2 identical molecules of DNA held together 1 chromosomes= either 1 DNA molecule or 2 DNA molecule Steps of Cell Replication G1 Interphase 4 Un-replicated chromosomes 4 DNA molecules S phase becomes replicated during S G2: interphase 4 replicated chromosomes 8 DNA molecules Mitosis Cytokinesis Mitosis produces identical daughter cells They are identical to each other They are also identical to the original parental cell, so in this case the cells are clones Steps of Mitosis Prophase The chromosomes condense down (fuzzy x structure), we are coming out of the G2 structure so all of the chromosomes are replicated and during prophase they attach to the spindle apparatus and the nuclear envelop breaks down 4 replicated chromosomes & 8 DNA molecules Metaphase
The chromosomes will line up along the center of the cell known as the equatorial plate, the centromere regions are lined up 4 replicated chromosomes lined up 8 DNA molecules Anaphase The replicated chromosomes get split up so now you have 8 un- replicated chromosomes 8 DNA molecules Each piece is considered a chromosome Telophase The chromosomes continue to move towards the poles of the spindle Nuclear envelopes start to reform We still have 8 un-replicated chromosomes in the cell 8 molecules of DNA Cytokinesis

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