CELL DIVISIONMEIOSIS & MITOSIS

The differences between Meiosis I and Meiosis II

MEIOSIS IMEIOSIS IISynapsis occursSynapsis does not occursCrossover occursCrossover does not occurDuring metaphase 1, 2 homologous chromosomes are paired and aligned on the metaphase plate During metaphase II, chromosomes with 2 chromatids are aligned on the metaphase plateHomologous chromosomes separate and move to opposite polesChromatids separate and move to opposite poles2 haploid cells are produced4 haploid cells are produced

SIMILARITIES BETWEEN MITOSIS AND MEIOSISBoth involve cell divisionBoth start from diploid cellsChromosomes duplicate only onceBoth involve the separation of chromatids in anaphase of mitosis and in anaphase IIBoth follow similar phases: prophase, metaphase, anaphase and telophase

DIFFERENCES BETWEEN MITOSIS AND MEIOSIS

MitosisAspects comparedMeiosis Produce new cellsPurpose Produce gametes for sexual reproductionSomatic cellsType of cellReproductive cellsSingle row of chromosomesAlignment of chromosomes during metaphaseDouble row of chromosomesDoes not happenSynapsis Happen in prophase I to form tetrads or bivalentDoes not happenChiasmata and cross-overIn prophase INoneGenetic variationYes during cross-overOnceFrequency of cytokinesis TwiceTwoNo. of cells producedFourDiploid (2n)No. of chromosomesHaploid (n)

IMPORTANCE OF CELL DIVISIONTo ensure continuity of life in earthControlled mitosis and meiosis produced properly functioning cellsCertain agents such as radiation & chemicals can disturb processes of mitosis meiosisPreservatives also can cause changes in DNA