Gene Chromosomes
They are located on the chromosomes. Chromosomes are the packed structure of a DNA with proteins.
Genes are composed of either DNA or RNA Chromosomes composed of DNA, RNA and histones.
According to Human genome project, there are 30,000 genes in the human cell. In Human cell there are 23 pair of chromosomes. In Gametic cell there are 23 chromosomes.
Gene mutation takes place at smaller scale. Chromosome mutation takes place at larger scale. In evolution it takes time.
Genetic mutation is not lethal. In fact is desirable at lower level of life. Chromosome mutation is generally lethal.
Gene is not visible under microscope. Chromosome is visible under microscope.