Bioscience in brief
An introduction to genes and crops
What is a Chromosome?
Extended DNA molecules would be very long (human DNA would be two meters long) but DNA is coiled and packaged in structures known as chromosomes. These are contained in the cell’s nucleus. Different species have different numbers of chromosomes (humans have 46 chromosomes, or 23 sets of chromosome pairs; peas have 14 chromosomes or 7 pairs; and tomatoes 24 chromosomes or 12 pairs).