Meiosis I

Prophase I

Homologous chromosomes pair during synapsis

Prophase I

Synapsis occurs, nuclear membrane breaks down

Prophase I

Spindle appears, nuclear envelope fragments and nucleolus disappears

Prophase I

Homologues line up side by side and crossing-over occurs

Crossing-over

When chromatids homologous chromosomes exchange pieces of DNA with each other

Crossing-over

Result is chromosomes have sister chromatids that are no longer identical

Metaphase I

Homologous chromosome pairs align at the metaphase plate

Anaphase I

Homologous chromosomes separate, pulled by centromeric spindle fibers

Metaphase I

Homologous pairs line up at metaphase plate

Metaphase I

No way to know which homologous chromosome will go to what pole

Metaphase I

One monologue is from maternal, other from fraternal

Independent Assortment

Occurs when homologues separate from each other during Anaphase I

Metaphase I

Independent Assortment

Telophase I

Daughter Cells have one chromosome from each homologous pair

Telophase I

Nuclear envelopes re-form

Telophase I

Nucleoli reappear

Telophase I

Cytokinesis may occur, producing two daughter cells which are haploid

Anaphase I

The homologous chromosomes, many who have crossed over, separate

Can’t predict what pole each homologue will go to

Independent Assortment

Generates cells with different combinations of maternal and paternal chromosomes

Interkinesis

Chromosomes still consist of two chromatids

Interkinesis

Period of time between Meiosis I & II

No replication of DNA