There are almost as many different types of four-wheel-drive systems as there are four-wheel-drive vehicles. It seems that every manufacturer has several different schemes for providing power to all of the wheels.
Human Male Chromosomes. In the normal karyotype of male chromosomes, 23 pairs of very long DNA molecules and their associated proteins carry the hereditary information of a man.
The sex chromosomes determine whether you are a boy (XY) or a girl (XX). The other chromosomes are called autosomes. The karyotype of a male human being. The largest chromosome, chromosome 1, contains about 8000 genes. The smallest chromosome, chromosome 21, contains about 300 genes.