1. Meiosis
Sunday, February 24, 2019

2. Meiosis Two cell divisions
These two divisions result in four products
Chromosome number is halved in the products of meiosis
Crossing over of genetic material occurs
2n to 2n to n
Sunday, February 24, 2019

3. Sunday, February 24, 2019

4. Meiosis Stages Interphase M1 (PMAT 1) M2 (PMAT 2) DNA Synthesis
Meiosis Phase 1
Separation of homologous pairs
M2 (PMAT 2)
Meiosis Phase 2
Separation of sister chromatids
Sunday, February 24, 2019

5. Question
During which process(es)/steps are sister chromatids seperated
Cell Cycle
Meiosis I
Meiosis II
A & B are correct
B & C are correct
A & C
All of the above are correct
None of the above is correct
Sunday, February 24, 2019

6. Vocabulary Homologous Homologous Chromosome
Similar by virtue of a common evolutionary origin. Homologous genes or proteins generally show similarities in their sequence.
Homologous Chromosome
One of two copies of a particular chromosome in a diploid cell, one from the father and one from the mother.
Sunday, February 24, 2019

7. Sunday, February 24, 2019

8. Interphase Chromosomes are replicated G1, S and G2 phase occur
Similar to what is seen during the Cell Cycle
G1, S and G2 phase occur
Sunday, February 24, 2019

9. Meiosis I 1st Cell Division
Prophase 1
Chromosomes condense
Homologous chromosomes come together
Once the homologous pairs are together, chiasmata (chiasma {singular} ) form.
Crossing over o genetic material occur at the chiasmata
Can last for days--or longer
Occupies more than 90% of the time require to complete meiosis.
Sunday, February 24, 2019

10. Question Which phase is the longest phase of Meiosis (entire process)?
Prophase
Prophase I of Meiosis II
Prophase II of Meiosis II
Prophase I of Meiosis I
Prophase II of Meiosis I
Two of the above are correct
Three of the above are correct
None of the above are correct
Sunday, February 24, 2019

11. Question At the end of Meiosis I, which of the following is correct?
Two Diploid cells are produced
One Diploid cell is produced
Four Diploid cells are produced
Two Haploid cells are produced
One haploid cell is produced
Four haploid cells are produced
None of the above is correct
Sunday, February 24, 2019

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16. Meiosis I Metaphase I Homologous pairs align at equatorial planes
Known as tetrads
Paired chromosomes line up in the middle and separate
Sunday, February 24, 2019

17. Potential Exam Questions
What align along the middle of the cell of
Metaphase of the Cell Cycle
Metaphase I of Meiosis I
Metaphase II of Meiosis II
Sunday, February 24, 2019

18. Meiosis I
Anaphase I
Homologous pairs are separated and pulled to opposite poles
Sister chromatids are pulled to the poles of the cell
However, the sister chromatids stay together
Centromeres do not divide
Sunday, February 24, 2019

19. Meiosis I Telophase I & Cytokinesis
Cleavage furrows form in animal cells
Cell plates form in plant cells
Nuclear envelope and nuclei re-form in some cells
Sister chromatids are still joined together
There is no further replication of genetic material before the 2nd cell division
Sunday, February 24, 2019

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21. Meiosis II 2nd Cell Division
Prophase II
Spindle apparatus forms and chromosomes progress towards the equatorial plane
Metaphase II
Sister chromatids arrange themselves on the equatorial plane (middle) of the cell
Sunday, February 24, 2019

22. Meiosis II
Anaphase II
Sister chromatids are pulled to opposite poles by spindle fibers
Centromeres divide
Sister chromatids are finally separated
Sunday, February 24, 2019

23. Question When are centromeres divided? Metaphase of the Cell Cycle
Anaphase of the Cell Cycle
Metaphase II of Meiosis I
Metaphase I of Meiosis II
Anaphase I of Meiosis II
A & B are correct
B & C are correct
Three of the above are correct
All of the above are correct
None of the above is correct
Sunday, February 24, 2019

24. Meiosis II Telophase II & Cytokinesis
Nuclei form at opposite poles of the cell
Cytokinesis occur
Four daughter cells with a haploid number of chromosomes
Sunday, February 24, 2019

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27. Comparison Distinct Differences Key Concepts*
Meiosis = 4 progeny cells [1 = 2 = 4]... thus 2 divisions
Mitosis = 2 daughter cells only... thus 1 cell division
Meiosis = one-half number of chromosomes
Mitosis = same # of chromosomes as parent cell
Meiosis = new combinations of gene not in parents & chromosomes sort randomly of each other
Mitosis = daughter cells are genetically identical
Sunday, February 24, 2019