Genetics is the study of genes = what they are, what they do, and how they work.
Genes, which are made up of DNA, act as instructions to make molecules called proteins.
A chromosome (as the X chromosome or the Y chromosome in humans)
of a sexually reproducing eukaryotic organism that is directly concerned
with the inheritance of sex, that contains the genes governing the
inheritance of various sex-linked and sex-limited characters, and that
is represented differently in the two sexes either by being present in
one and not the other or by being present a different number of times in
one sex compared to the other—called also hetero chromosome or sex chromosome
I hope it may helps you...