What is sex linkage?
Sex linkage is a type of genetic disease, where the gene with the faulty allele is carried on the X chromosome.
Women have 2X chromosomes whilst men only have 1. Consequently if the diseased allele is recessive, males always express it in their phenotype if it is present in their genotype (XhY) whereas women require 2 recessive alleles to show expression (homozygous XhXh). Therefore women can only be effected if both her mother and father contain the allele. Women can be carriers (XhXH).
A key example is haemophillia.
KD
Related Biology A Level answers
All answers ▸What happens during prophase?
How do fish carry out gas exchange efficiently?
DNA mismatch repair enzymes repair mainly bases on the newly synthesised DNA strand, using the old DNA strand as a template. If the mismatches were simply repaired without regard for which strand served as template, would this reduce replication errors ?
A patient is infected by a pathogen. Explain the process of the imitation of the immune response (5 marks) The paitent was prescribed antibiotics yet their symptoms did not improve. What can you infer from this? (1 mark)?