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Meiosis Notes
December 7, 2015
Meiosis – What is it?
 a type of cell division that results in four daughter cells each with
half the number of chromosomes of the parent cell, as in the
production of gametes and plant spores.
 ensures that offspring are genetically different from their parents.
Significance of Meiosis
 results in gametes (sex cells)!
 Major source of variation, which leads to Natural Selection
Meiosis
 Starts
diploid and
ends
haploid
through 8
steps
Stages of meiosis
Meiosis I
 Prophase 1 – The chromosomes
condense, and the nuclear envelope
breaks down. Crossing over occurs.
 Metaphase 1 – Pairs of homologous
chromosomes move to the equator of
the cell.
 Anaphase 1 – Homologous
chromosomes move to the opposite
poles of the cell.
 Telophase 1 – Chromosomes gather at
the poles of the cells.
Meiosis II
 Prophase 2 – A new spindle forms around
the chromosomes.
 Metaphase 2 – Chromosomes line up at
the equator.
 Anaphase 2 – Centromeres divides.
Chromatids move to the opposite poles
of the cells.
 Telophase 2 – A nuclear envelope forms
around each set of chromosomes.
Crossing Over in
 The exchange of genes between homologous chromosomes,
resulting in a mixture of parental characteristics in offspring
 Results in new gene combinations
 This is why you have some genes from your mom and some from your dad!
Life Cycle including Mitosis and Meiosis