You are viewing a free preview of this lesson.
Subscribe to unlock all 10 lessons in this course and every other course on LearningBro.
This lesson covers the inheritance of genes located on sex chromosomes (sex linkage) and genes on the same autosome (autosomal linkage), as required by the Edexcel A-Level Biology specification (9BI0, Topic 8).
Human sex is determined by the sex chromosomes:
| Sex | Chromosomes | Gametes |
|---|---|---|
| Female | XX | All eggs carry an X chromosome |
| Male | XY | Sperm carry either X or Y |
The SRY gene on the Y chromosome triggers male development. In its absence, female development occurs by default.
Sex-linked genes are genes located on the sex chromosomes. In practice, most sex-linked conditions involve genes on the X chromosome (X-linked) because the Y chromosome carries very few genes.
Key features of X-linked inheritance:
Subscribe to continue reading
Get full access to this lesson and all 10 lessons in this course.