Final answer:
X-linked traits are inherited on the X chromosome. These traits are more commonly expressed in males since they have only one copy of the X chromosome. The Y chromosome is smaller and contains fewer genes, which influences the inheritance patterns of sex-linked traits.
Step-by-step explanation:
X-linked (also called sex-linked traits) are inherited on the X chromosome. Genes that are located on the sex chromosomes are known as sex-linked genes, and most of these are found on the X chromosome, which is one of the two types of sex chromosomes in humans. The reason for this is that the Y chromosome is much smaller and contains fewer genes compared to the X chromosome. In human genetics, females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).
When examining inheritance patterns for X-linked traits, it is important to understand that males have only one X chromosome, and thus only one copy of each gene located on the X chromosome. This means that if a male inherits an X-linked recessive trait, he will express that trait because he does not have a second X chromosome to potentially mask the recessive allele. Females, on the other hand, have two X chromosomes, so they can be carriers of recessive X-linked traits without expressing them, unless they have two copies of the recessive allele.
X-linked dominant or recessive inheritance depends on whether the trait is dominant or recessive. A characteristic example of an X-linked trait is hemophilia, which is a recessive trait predominantly affecting males due to its inheritance pattern involving the X chromosome.