Variation + SR (meiosis) Flashcards
Prior to meiosis I
The chromosomes which have replicated prior to meiosis I, each consist of 2 genetically identical chromatids attached at the centromere
Meiosis I step 1
The chromosomes condense and the homologous chromosomes pair up
Meiosis I step 2
Chiasmata form at points of contact between the non-sister chromatids of a homologous pair and sections of DNA are exchanged
Meiosis I step 3
This crossing over of DNA is random and produces genetically different recombinant chromosomes
Meiosis I step 4
Spindle fibres attach to the homologous pairs and line them up at the equator
Meiosis I step 5
The orientation of the pairs of homologous chromosomes at the equator is random
Meiosis I step 6
The chromosomes of each homologous pair are separated and move towards opposite poles
Meiosis I step 7
Cytokinesis occurs and two daughter cells form
Meiosis II
Each of the two cells produced in meiosis I undergoes a further division during which the sister chromatids of each chromosome are separated