Pask, Andrew J. Department of Zoology, University of Melbourne, Melbourne, Victoria, Australia.
- The X chromosome
- The Y chromosome
- Other sex chromosome systems
- Links to Primary Literature
- Additional Readings
The genome of every mammal consists of the autosomal chromosomes (or autosomes), of which all individuals normally carry two copies, and the sex chromosomes, which vary in number and type with the individual's sex. In mammals, the sex chromosomes are called the X and Y chromosomes. In placental and marsupial mammals, females have two X chromosomes, whereas males have one X chromosome and one Y chromosome (see illustration). (Note that monotreme mammals have a different X/Y system, which will be discussed briefly in this paper.) Some other types of animals determine sex through different chromosome systems, but the mammalian X/Y system is particularly well studied. The difference in the distribution of the sex chromosomes between males and females is a unique feature of the mammalian genome. Because all the mammalian autosomes exist in duplicate, there are two copies of all autosomal genes. This means that there is, in effect, a backup of each autosomal gene. If one gene copy is mutated, these duplicate chromosomes can undergo recombination to repair the damaged DNA.
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Its dedicated editorial team is led by Sagan Award winner John Rennie. Contributors include more than 9000 highly qualified scientists and 42 Nobel Prize winners.
MORE THAN 8500 articles and Research Reviews covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 17,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information