Gene Expression

DNA

• DNA contains the instructions an organism needs to develop, function, and reproduce. Small differences in the DNA within a species cause the differences in appearance we see between individuals.
• In eukaryotes, most of the cell's DNA is located in the nucleus, associated with proteins that help it up. A small amount is located in mitochondria and in the chloroplasts of plants.
• The DNA in eukaryotes is packaged into chromosomes. Each chromosome consists of a DNA molecule and packaging proteins. The number and appearance of chromosomes is specific to the species.