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