EBIO 1030 Lecture Notes - Lecture 11: X-Inactivation, Punnett Square, Y Chromosome
Document Summary
Sperm cells with an x or a y determine the genetic sex of human offspring. Sry gene on y chromosome leads to testes development. In each female cell, one x-chromosome is inactivated and is condensed into a. Ensure s an equal expression of genes from the sex chromosomes since females have 2 x-chromosomes and males have only 1. Most sex-linked disorders are recessive ( x linked recessive) Less likely to express trait: must have two defective x chromosomes. Men are more likely to express the trait. One x chromosome - will express whatever is on that chromosome, even a single recessive allele. Y chromosome is small and missing a lot of genes. Example of an x linked recessive disorder. Red green color blindness: altered structure of photoreceptors in the eyes. Affects 8 percent of men and less than 1 percent of women\ Diseases caused by recessive, sex-linked alleles should be more commonly expressed in.