Our guide picked us up and entertained us the whole way, taking us to the best spots â we even had a close encounter with a bear on the side of the road! This wildlife photo tour will explore the wildlife, geology, and natural history of Grand Teton National Park.
Chromosomes contain smaller units of genetic material called DNA. DNA is a sequence of letters that spell out the genetic code. The DNA is organized into words and sentences called genes. Humans have approximately 20,000 genes and each one influences a part of development. These genes usually come in pairs.
A human cell has genetic material contained in the cell nucleus (the nuclear genome) and in the mitochondria (the mitochondrial genome). In humans the nuclear genome is divided into 46 linear DNA molecules called chromosomes, including 22 homologous chromosome pairs and a pair of sex chromosomes. The eukaryotic DNA is organized in one or more linear molecules, called chromosomes, which are associated with histone proteins. 2  All chromosomal DNA is stored in the cell nucleus, separated from the cytoplasm by a membrane. 3  Some eukaryotic organelles such as mitochondria also contain some DNA.