THE NATURE and SCOPE OF PSYCHOLOGY LESSON AIM Define psychology and explain basic theoretic approaches Despite their interest in the subject, students of psychology often find it difficult to answer this basic question in a clear, concise an d specific manner.
X-linked recessive inheritance is a mode of inheritance in which a mutation in a gene on the X chromosome causes the phenotype to be expressed in males (who are necessarily hemizygous for the gene mutation because they have one X and one Y chromosome) and in females who are homozygous for the gene mutation, see zygosity.
Females have two X chromosomes; males have one X and one Y. Genes on the X chromosome can be recessive or dominant. Their expression in females and males is not the same. Genes on the Y chromosome do not exactly pair up with the genes on the X chromosome.