DNA
From ChildWiki.com
DNA is a substance that carries all the genetic information of a cell. Each strand of DNA is made of thousands of genes. A gene is a recipe for building a protein molecule. Proteins are the building blocks of the body. They also work within the cell to perform various tasks. The information in the genes of the cell tell the cell what its function will be and determine the protein composition.
The DNA is located in the center, or nucleus, of the cell. The DNA is organized into pairs of chromosomes. Each cell needs to carry the genetic information for the whole body, so each time a cell divides it must copy the DNA. When the cell needs to create proteins, it uses RNA to transcribe the DNA. The RNA then travels outside the nucleus to build proteins for the cell.
[edit] Problems
When DNA replicates itself prior to cell division, it can sometimes make a mistake. This can be big or small, and can lead to chromosomal abnormalities. As a parent ages, their reproductive cells become more likely to make mistakes when copying DNA. Every person should have 46 chromosomes in 23 pairs. Half of each pair comes from one parent, half from the other. If the cell makes a mistake when it divides, the resulting cells might have an extra chromosome, or one missing. The most common chromosomal abnormalities involve the wrong number of chromosomes. Other mistakes in DNA replication include deletion of a small amount of a chromosome, translocation of one part of a chromosome onto another, inversion of a small section that is flipped upside down, duplication of only a section of a chromosome, and deletion of material at both ends of a chromosome with the new ends joined to form a ring. Some of these abnormalities have no effect on health or development.
