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[[File:Morgan crossover 1.jpg|thumb|right|350px|<center>Autosomal Recombination<center>]] | [[File:Morgan crossover 1.jpg|thumb|right|350px|<center>Autosomal Recombination<center>]] | ||
In humans, 95% of DNA is autosomal DNA. It consists of 22 pairs of chromosomes and in each pair, one is from mom and one is from dad. The pairs of chromosomes are simply names 1, 2, 3, etc... 21, 22. They are mostly named by their size with chromosome 1 being the largest, chromosome 2 being the second largest etc. They are not perfectly named by their size, for example chromosome 22 is actually bigger than chromosome 21, chromosome 20 is slightly bigger than chromosome 19 etc. This is because as our understanding of DNA grows and improves, some chromosomes turned out to be a little bigger or smaller than we initially thought. | |||
Autosomal DNA is the most important and most commonly tested type of DNA. A child will have exactly half of their autosomal DNA from each parent. However, a child will usually not have exactly 25% from each grandparent. A child could have 20% from one grandparent and 30% from another grandparent for example. This is because each child is randomly given half of their parent's DNA. When a new sperm or egg is formed, the pairs chromosomes in the parent line and exchange information, meaning segments are randomly cut out and switch places with each other to form new chromosomes that are a mixture of the previous ones. The child is then given one chromosome from each pair and the other is discarded. This happens in both parents so that the child receives one full set of chromosomes from each parent. | Autosomal DNA is the most important and most commonly tested type of DNA. A child will have exactly half of their autosomal DNA from each parent. However, a child will usually not have exactly 25% from each grandparent. A child could have 20% from one grandparent and 30% from another grandparent for example. This is because each child is randomly given half of their parent's DNA. When a new sperm or egg is formed, the pairs chromosomes in the parent line and exchange information, meaning segments are randomly cut out and switch places with each other to form new chromosomes that are a mixture of the previous ones. The child is then given one chromosome from each pair and the other is discarded. This happens in both parents so that the child receives one full set of chromosomes from each parent. | ||