INDEPENDENT ASSORTMENT

branch GENETICS

Coming from MEIOSIS
Leading to DIHYBRID CROSSES
=Independent Assortment= '''The random arrangement of homologous chromosomes during meiosis I results in gametes with a unique combinations of alleles'''. This is known as independent assortment. [image:http://i.imgur.com/9a0xEjG.png?2] During meiosis I (first division), chromosomes pair up side by side. Each of the resulting daughter cells will receive one chromosome from each pair. For example, here we have started with a cell that only has two pairs of chromosomes (smaller and larger). When this cell undergoes its first division, each daughter cell will receive one of the larger chromosomes and one of the smaller chromosomes. However, which one of the large chromosomes the daughter cell receives is completely independent of which smaller chromosome it receives. We call this Independent Assortment. If we have 23 pairs of chromosome and each time we randomly take one chromosome from each pair, then we can make more than 8 million different combinations. You can think of this like a deck of cards, where each card represents a chromosome. Homologous chromosomes might be represented by cards with same number and colour (so there is always a pair). The cards are shuffled and then dealt between two players ensuring that each player always get's one card from each pair (e.g. that both players get a red 10). Independent assortment essentially acts like shuffling the deck. Each time a hand is dealt (gametes are formed), a new combination of chromosomes results.