Alleles: Genetic Differences

Sometimes when you look at two children from one family, and they look so different, you think one of them must be adopted. However, this is not necessarily the case. It is possible for parents to have children that look completely different from their parents. Each parent has 46 chromosomes divided into pairs of two. The pairs are one from the maternal side and one from the paternal side. Each parent passes on 23 chromosomes, one from each pair. This is randomly selected which chromosome gets passed on. Alleles are a variant of the gene within the chromosomes. With various combinations of alleles, there are over 8 million different human possibilities to occur from one couple. This is why two parents can have children that are all different.

Meiosis is a process of cell division, chromosomes are copied, sometimes incorrectly, paired up and divided. In meiosis there is crossing over in which there is an exchange of the genetic material. In the crossing over, it becomes a woven network of the proteins until they have switched places. This is the same for certain processes, which can also affect the DNA. There are two stages of meiosis, also known as meiosis I and meiosis II. The chromosomes are diploid, meaning into two segments and then divide again into four haploid daughter cells. Mendel came up with the Law of Independence, which is that the alleles separate different from each other during gamete formation or meiosis. The different traits are inherited separate from each other. Within meiosis I the first stage is prophase I is where the chromosomes condense and the crossing starts to happen after the nuclear envelope breaks down. Next comes metaphase I. In Metaphase I, the paired homologous chromosomes move to the center of the cell. Anaphase I is next, the chromosomes now move to the opposite poles of the cell. Telophase I, the chromosomes gather at the poles or end of the cells and there is a division of the cytoplasm. Now we begin with meiosis II, which occurs in four stages. In prophase II, a spindle forms around the chromosome. Next comes metaphase II, which the chromosomes line up at the middle of the cell or the equator. In

These mistakes like our own have a range of causes and effects, however these mistakes cause mutations in our body. Changes or mutations are not always bad and, sometimes changes that matter to evolution are naturally occurring and can happen slowly over time. When a cell divides, it makes a copy of its DNA, and sometimes copying incorrectly causing errors due to either incomplete or imperfect replication. This imperfection can even be a complete deletion of a genetic code. That small difference from the original DNA is a mutation. Mutations can affect a group of genes or whole chromosome and usually happens during meiosis. It can happen during the crossing over, random fertilization, or different arrangement of chromosomes. Mutations can cause either a large problems such as cystic fibrosis, small problems such an extra toe or even webbed