Images to Go with Meiosis Drawings
Chromosomes must condense at the beginning of any Prophase so that they will be visible. Note:
there are two chromatids because the DNA was replicated in Interphase (during “S”).
Single chromosome consisting of
two chromatids,
two pieces of DNA (replication)
http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/113158606/18847_6.jpg
Meiosis begins with a diploid cell containing 23 pairs of homologous chromosomes (in humans).
In the diagram, below, the homologous pairs are shown in two colors to indicate the set of 23
single chromosomes that came from the mother (yellow) and the set of 23 that came from the
father (blue). The result is 23 matched pairs of homologous chromosomes in this individual.
Note: each yellow or blue chromosome is made up of two chromatids (see drawing above).
http://biosocialmethods.isr.umich.edu/wp-content/uploads/2014/10/karyotype.png
Independent assortment of chromosomes at metaphase I of meiosis is an import factor
contributing to genetic variation of the offspring. This diagram could be showing only pair #5
and pair #13 from above. Depending on the arrangement of these homologous pairs, each of the
resulting gametes will carry different genetic information to a potential fetus.
https://cdn.goconqr.com/uploads/image_clipping/image/313931/desktop_independent_sdfkhsdf.jpg
Independent assortment: arrangements of chromosomes in metaphase I. These could be the
pairs 3, 5 and 13 (from above). There are even more possible arrangements than you see here.
http://www.bio1100.nicerweb.com/Locked/media/SAVE/ch09/09_06.jpg
Crossing over—chiasma / chiasmata (pl.) occurs in meiosis between prophase I and metaphase I.
It is the process where homologous chromosomes pair up with each other and exchange different
segments of their genetic material to form recombinant chromosomes.
http://ib.bioninja.com.au/_Media/crossing-over_med.jpeg
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Crossing over (chiasmata): when recombinant chromatids (chromosomes) and non-recombinant
chromatids are distributed into individual gametes (plus independent assortment) the resulting
gametes will provide even more genetic variation to the potential fetus. Note: there are two
points of chiasmata in both the photograph and the matching diagram.
https://image.slidesharecdn.com/13meiosisandsexuallifecycles-130311053433-phpapp02/95/13-meiosisand-sexual-life-cycles-58-638.jpg?cb=1362980157