And the other pair, the final pair of chromosomes, is known as the sex chromosome pair. Now, in this lecture, we're going to focus on the sex chromosomes. Now, the first major difference between autosomal chromosomes and sex chromosomes is the following. In autosomal chromosome pairs, the two homologous chromosomes are always the same size and shape. But in the case of sex chromosomes, in females, the two sex chromosomes are the same size and shape. But in males, we have one large sex chromosome and one small sex chromosome.