Explaining how an allele is different from a gene and the relationship between the two.

A GENE is a sequence of DNA that can be translated into a protein.

An ALLELE is a version of a gene. We have two alleles of every gene, located on the same spot on different chromosomes. For example, the gene for eye color can either be the allele blue or the allele brown, but they are the same gene!

                                       

A chromosome is just a name for the structure DNA in a cell takes. Depending on the specie, there will be a different numbers of chromosomes, but they will always exist in pairs. Humans have 23 chromosome pairs, which makes 46 chromosomes in total. A chromosomal pair will contain the same genes, but in different alleles. 

So genes are sequence of DNA chromosomes are the structure DNA takes in a cell, each cell have 2 version of each gene, and there versions are called alleles.