To understand genetics , you first need to understand a few key concepts and the relationships between cells , chromosomes , genes , and DNA .
There are two types of cells : prokaryotic ( bacteria ) and eukaryotic ( plant , animal , fungi ).
At a microscopic level , we are all composed of CELLS . In fact , the average human body is made up of 37.2 trillion cells . Our muscles , our organs , our hair , and even our teeth are made up of cells . Every single piece of us !
In eukaryotic cells , the nucleus serves as the command center , directing the cell to grow , mature , divide , or die . It is here where the cell ’ s genetic material - DNA - is stored . Within the nucleus of every cell , DNA is packaged into thread-like structures called chromosomes .
Cells are the basic building blocks of all living things ; stand-alone living entities able to eat , grow , and reproduce . Cells group together to form tissues , which in turn group together to form organs , like the heart and brain .