1 / 9

NOTES 21 - Sex-Linked Inheritance

This article explores how sex is determined in humans and how sex-linked traits are inherited differently in men and women. Learn about the role of the X and Y chromosomes and the impact on passing on these traits to offspring.

cgaines
Download Presentation

NOTES 21 - Sex-Linked Inheritance

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. NOTES 21 - Sex-Linked Inheritance In humans, sex is determined by the 23rd chromosome pair

  2. How is sex determined in humans? • Father’s 23rd pair is an X and a Y • Mother’s 23rd pair is an X and an X • Humans egg cells always have an X chromosome • Human sperm cells have either an X or a Y chromosome • If a sperm with an X fertilizes the egg, the 23rd pair will be XX and it will be a female • If a sperm with a Y fertilizes the egg, the 23rd pair will be XY and it will be a male

  3. Sex-linked traits – Traits carried on the X chromosome (23rd pair in humans) • The X chromosome has many genes on it • The Y chromosome has very few genes on it

  4. Sex Chromosomes

  5. Sex-linked traits are inherited differently in men and women • Females have two X chromosomes, so they have 2 genes for all traits carried on the 23rd pair • Males have one X chromosome, so they only have 1 gene for all traits carried on the 23rd pair

  6. Inheritance of a Sex-Linked Trait

  7. Whether or not recessive sex-linked traits get passed on depends on the sex of the parent and the sex of the offspring • Males pass their X chromosome (and its genes) to all of their daughters and none of their sons • Females pass one of their X chromosomes (and its genes) to all of their children • Fathers cannot pass sex-linked traits to their sons, and always pass them to their daughters • Males only inherit sex-linked traits from their mothers, so if a son receives an X chromosome with a recessive allele from his mother, he automatically will have the recessive trait

  8. Carrier – a female with a recessive allele on one of her X chromosomes Ex. Color blindness is caused by a recessive allele on the X chromosome

  9. Ex. Color blindness is caused by a recessive allele on the X chromosomeXC = normal vision Xc = color blind • XCXC = normal female • XCXc = normal female carrier • XcXc = color blind female • XCY = normal male • XcY = color blind male

More Related