Chromosomes are thread like structures made up of Genes. A Gene codes for a specific inherited characteristic ( eg. hair colour, blood group etc.) They are a region of chromosomal DNA which on average consist of a thousand nucleotides. They code for a persons characteristic by coding for the protein that is synthesised through transcription and translation.
In the human chromosome complement 22 pairs of homologous chromosomes are called autosomal and play no part in the sex determination. One pair are the sex chromosomes and determine the sex of an individual. a human female has two X chromosomes and a male has an X and a Y. For example the karyotype on the left shows a male's set of chromosomes.