Chromosomes X and Y Chromosomes X and Y do not truly make up a homologous pair

Chromosomes x and y chromosomes x and y do not truly

This preview shows page 2 out of 2 pages.

Chromosomes X and Y Chromosomes X and Y do not truly make up a homologous pair. They act similarly in their roles, but they are not homologous (the same). The X chromosome in humans is much longer than the Y chromosome and also contains many more genes. These genes are said to be sex-linked, due to the fact they are present in one of the sex chromosomes. During fertilization, when the opposing homologous chromosomes come together, the smaller Y chromosome offers no dominance against the ‘extra’ X chromosomes as indicated below. The arrows indicate sex-linked genes in the X chromosome. In this homologous pairing, all those genes are dominant, because there are no opposing genes in the Y chromosome to offer dominance. So when the organism has an XY chromosome complement (i.e. a male), these sex-linked genes are freely expressed in the organism phenotype . Sex-Linked Characteristics These sex-linked genes on the X chromosome display a number of characteristics. The following are just some examples of phenotypes as a result of these genes in expression; Red-Green color blindness Hemophilia – A condition which prevents the clotting of the blood More information on sex-linked characteristics and how they are passed on from generation to generation will be available in new areas of the site soon. The next tutorial looks at genetic mutations and the consequences as a result of them.
Image of page 2

You've reached the end of your free preview.

Want to read both pages?

  • Fall '19
  • Jones

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Stuck? We have tutors online 24/7 who can help you get unstuck.
A+ icon
Ask Expert Tutors You can ask You can ask You can ask (will expire )
Answers in as fast as 15 minutes