Help with meiosis?

Question

How do the events of meiosis explain Mendel's law of independent assortment?

Answer 1

Law of Independent Assortment: Mendel deduced the first 2 laws by using a monohybrid cross. This is a genetic cross containing 1 trait. Mendel was lucky in choosing the characteristics he worked with, since the were not linked and found on separate chromosomes. In a dihybrid cross, 2 trait cross, there are many possible chromosome combinations during gamete formation. Each chromosome seems to have a mind of its own when choosing which sperm or egg cell to enter. Each chromosome does not have a mind but the rules of chance take over in determining where they are to go. This is called independent assortment. Let us look at a simple example: RrYy represents one parent with the characteristics R and r for skin texture and Y and y for hair texture. The parent is heterozygous for both characteristics. During gamete formation (meiosis) one of the R's and one of the Y's need to be in each sperm cell. If this does not happen the offspring will have too many Y's or too few R's and visa versa. The possible gametes must have one R and one Y to be effective. RY, rY, Ry, and ry are the only possible combinations allowed. This individual has the possibility of producing any one of these gametes from the original RrYy cell. If the other parent has the same genotype (arrangement of genes) the gametes would be the same. If a genetic cross were made there would be 16 possible combinations of offspring from that mating. 9 would be dominant for both characteristics, 3 would be dominant for R and recessive for y, 3 would be dominant for Y and recessive for r, and 1 would be recessive for both characteristics. This can only occur if 2 or more traits are being used and they are on separate chromosomes.

Answer 2

"Independent assortment occurs during meiosis I in eukaryotic organisms, specifically anaphase I of meiosis to produce a gamete with a mixture of the organism's maternal and paternal chromosomes."