Biological Concepts — Lab 2 online
MITOSIS and MEIOSIS

Instructions:
Study all the visual information in this online lab, plus the accompanying explanations.
Be prepared to answer a few "check-in" questions to show that you were paying attention.







MITOSIS
Mitosis is cell division (or, more properly, division of the nucleus of the cell) in which the chromosome number is maintained.
Mitosis is most familiar in the diploid somatic cells of multicellular organisms, but it also occurs in haploid cells and in unicellular organisms.

Mitosis can be broken down into four phases:
  • PROPHASE:   The chromosomes become visible; the nuclear envelope breaks down; the spindle forms.
  • METAPHASE:   The chromosomes line up in the center of the cell to form a metaphase plate.
  • ANAPHASE:   The spindle pulls the chromosomes apart to opposite ends of the cell.
  • TELOPHASE:   The chromosomes regroup and a new nuclear envelope forms around them.
Mitosis is followed by cytokinesis, the division of the cytoplasm. Cytokinesis is a much simpler process than mitosis. It often begins before telophase has completely ended.

























MITOSIS IN PLANT CELLS
(onion root tip)




MITOSIS IN ANIMAL CELLS
(whitefish blastula)





MEIOSIS

Meiosis is a type of cell division that begins with a
single diploid cell and finishes with four haploid cells.
These haploid cells generally become gametes.


Overall scheme of meiosis



Meiosis involving one 'metacentric' chromosome pair (centromere centered between two arms of similar
length) and one 'telocentric' pair (centromere near one end, between long and short arms). Notice that
each resulting gamete has one chromosome of each type.   Paternal chromosomes (from the father)
and maternal chromosomes (from the mother) are shown in different colors.



Details of the stages of meiosis.



Further details of meiosis I




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Click here for the
Check-In questions



——     Rev. Aug. 2020     ——