10.1 Meiosis
Anaphase II
Chromatids of each chromosome separate and move to each end of the cell.
Metaphase II
Chromosomes (each with 2 chromatids) line up along the equator. (They are not in homologous pairs)
Prophase II
Chromosomes condense and become visible. Nuclear membrane dissolves and spindle fibres re-appear.
Telophase 1
Cytoplasm divides, two smaller daughter cells are formed
Prophase 1 (early)
DNA condenses, chromosomes become visible.
Sister chromatids
Duplicate copies of DNA, making up the single strands of double stranded chromosomes.
Random orientation of homologous pairs
Each of the chromosomes in a homologous pair line up randomly on the spindle in meiosis 1
Metaphase 1
Homologous chromosomes (Tetrads) line up alone equator
Prophase 1 (late)
Homologous chromosomes (each with 2 chromatids) pair up and form tetrad. Crossing-over occurs at points called "chiasmata"
First division of Meiosis
Is called "reduction division", because it reduces the number of chromosomes by half.
Telophase II
Nuclear membrane reforms, cytoplasm divides. In total 4 haploid daughter cells are formed.
Non-sister chromatids
Single strands of two different but homologous chromosomes.
Anaphase 1
Spindle fibres separate each of the homologous chromosomes to opposite sides of the cell.
Second division of Meiosis
Splits the two chromatids on each chromosome so that each daughter cell has one chromatid per chromosome.
Independent assortment of genes
The alleles of two different genes independently put into gamete cells.
Crossing over
The exchange of genetic material between homologous chromosomes during prophase I of meiosis
Chiasmata
The site of crossing over of the non-sister chromatids of homologous chromosomes