DNA is the name of a tiny part of every living things that is like a blueprint telling other cells how to develop.
Genetics is the study of genes—what they are, what they do, and how they work. In the middle of every single one of the 37 trillion cells in our bodies is a core that stores the information for living. It is called a nucleus. There are tiny strings of molecules inside known as genes. They are strung together in such a way that the arrangement - the sequence - of them carries information: that information determines how living organisms inherit various features. For example, children look like a combination of features of their parents because they have inherited some of each of their parents' genes.
The idea of genetics is to find the features that are inherited, and explain how these features pass from generation to generation.
As well as inheritance, genetics studies how genes are turned on and off to control what substances are made.
This can be helpful in finding out about diseases and moving towards cures.
Not all features are inherited. For example, a person's height is a result of both genetics and how healthily they live. Thus for example, children in China are strikingly bigger than their parents because they lead healthier, fitter lives because their diet is better than in the time of their parents.
Chromosomes are tiny packages which contain one DNA molecule. Humans have 46 chromosomes (23 pairs). The DNA molecule is a twisted spiral called a double helix.
When people make children, some special cells unwind their helixes, and share them with cells from their partner. The helixes then recombine, this time with properties from both parents. After this, the cells develop into babies.
In normal living, cells die and new cells form, but in these cases, cells simply divide up and produce copies of themselves. So we don't change genes during our lifetimes.
There are about 3.2 billion pairs of bits of data on all the human chromosomes: this is called the human genome. The order of them carries our genetic information. Think of each piece as like a letter of the alphabet. Words and sentences are made of these letters and then they make sense and tell us something. The genetic code is the same idea.
Mutations are random changes in genes creating new features in a living thing. These sometimes help, but can also harm, or have no new effect on the chances of a living thing surviving. This is what causes evolution.
