Q) Explain how mitosis give rise to genetically identical cells
Main points | |
Key idea: | What is mitosis |
· A process in which a nucleus divides to produce 2 daughter nuclei, each containing the same no. of chrom as original nucleus · Consist of prophase, metaphase, anaphase and telophase | |
Key idea: | Duplication of chromosome (DNA) during S phase |
· Mitosis is preceded by interphase · During S phase ( interphase), DNA replicates in a semi-conservative manner - each chrom is duplicated · Forms a double struc consisting of two genetically identical sis chromatids joined at centromere · Each chromosome condense during prophase (of mitosis) | |
Key idea: | Equal distribution of chrom in daughter nuclei due to metaphase & subsequent anaphase |
· Arrangement of chrom on the equator of cell during metaphase ensures equal distribution of chrom b/w daughter cells · Reason : During anaphase, centromere of each chrom divides, 2 genetically identical sis chromatids of each chrom separates to opp poles of cell · Ref to migration of sis chromatids aided by shortening of pole-to-centromere spindle fibres + when separated, each sis chromatid is now a new chrom*(iv) | |
Key idea: | Formation of genetically identical daughter cells by subsequent cytokinesis |
· By end of telophase, both daughter nuclei at opp poles will each consists of a set of genetically identical chromosomes · By end of cytoplasmic division (i.e. cytokinesis), genetically identical (daughter) cells are formed | |
Comments: (i) Visualize the answer with the aid of a labelled diagram. (ii) Verbalize the answer + write down the main points w/o referring to the answer (use abbreviations) (iii) Read again within the next 24h & once more within 72h (do not spend more than 10min) (iv) *At this point (anaphase), the no. of chrom in the cell has doubled | |
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