Interphase
Events of Interphase
Chromosomes (uncondensed in this phase) replicate in preparation for meiosis.
Nuclear membrane breaks down.
Homologues move toward the center of the cell and line up.
Homologues separate and are pulled to opposite poles.
Prophase I
Events of Prophase I
1.
Homologous pairs of sister chromatids come together and cross over.
Spindle forms.
Nuclear membrane breaks down.
Replicated chromosomes condense.
2.
Homologous pairs of sister chromatids come together and cross over.
Spindle forms.
Nuclear membrane breaks down.
Replicated chromosomes condense.
3.
Homologous pairs of sister chromatids come together and cross over.
Spindle forms.
Nuclear membrane breaks down.
Replicated chromosomes condense.
4.
Homologous pairs of sister chromatids come together and cross over.
Spindle forms.
Nuclear membrane breaks down.
Replicated chromosomes condense.
Metaphase I
Events of Metaphase I
Sister chromatids (replicated chromosomes) condense.
The cell pinches into two daughter cells.
Homologues move toward the center of the cell and line up.
Nuclear membrane breaks down.
True or False:
When homologues line up in the center of the cell in Metaphase I, they arrange
themselves in random order to facilitate crossing over.
True
False
Anaphase I
Events of Anaphase I
Homologues move toward the center of the cell and line up.
Homologues separate and are pulled to opposite poles.
Spindle forms.
Nuclear membrane breaks down.
True or False:
When sister chromatids are pulled to opposite poles in Anaphase I, they are
a mix of maternal and paternal genetic material.
True
False
Telophase I & Cytokinesis
Events of Telophase I & Cytokinesis
1.
Chromosomes may unwind slightly.
Sister chromatids arrive at the cell poles and the nuclear membrane reassembles around them.
Nuclear membrane breaks down.
The cell pinches into two daughter cells.
2.
Chromosomes may unwind slightly.
Sister chromatids arrive at the cell poles and the nuclear membrane reassembles around them.
Nuclear membrane breaks down.
The cell pinches into two daughter cells.
3.
Chromosomes may unwind slightly.
Sister chromatids arrive at the cell poles and the nuclear membrane reassembles around them.
Nuclear membrane breaks down.
The cell pinches into two daughter cells.
True or False:
At the end of meiosis I, there is a brief interphase prior to Prophase II.
Chromosomes do not replicate during this brief interphase.
True
False
Prophase II
Events of Prophase II
1.
The nuclear membrane reassembles around the chromosomes.
Chromosomes in daughter cells condense.
Homologues separate and are pulled to opposite poles.
Spindle forms.
2.
The nuclear membrane reassembles around the chromosomes.
Chromosomes in daughter cells condense.
Homologues separate and are pulled to opposite poles.
Spindle forms.
Metaphase II
Events of Metaphase II
Spindle forms.
The cell pinches into two daughter cells.
Sister chromatid pairs line up at the center of the cell.
Sister chromatids are pulled apart by the spindle fibers toward opposite cell poles.
True or False:
"Homologous pairs" and "sister chromatids" are just two different names for the same structures.
True
False
Anaphase II
Events of Anaphase II
The cell pinches into two daughter cells.
Sister chromatids are pulled apart by the spindle fibers toward opposite cell poles.
Chromosomes may unwind slightly.
Homologues separate and are pulled to opposite poles.
Telophase II & Cytokinesis
Events of Telophase II & Cytokinesis
1.
Nuclear membrane breaks down.
The two daughter cells pinch into four haploid daughter cells.
Spindle forms.
The nuclear membrane reassembles around the chromosomes.
2.
Nuclear membrane breaks down.
The two daughter cells pinch into four haploid daughter cells.
Spindle forms.
The nuclear membrane reassembles around the chromosomes.