Proteins: amino acid chains folded into a huge variety of structures: ex: hemoglobin, alpha/beta fibrils (cause alzheimer"s), motor proteins on a, different structures allow huge diversity of functions microtubules, photosynthetic reaction center. Gene: subunits within dna molecules that specifies (codes for) amino acids in 1 protein. Remember that dna is long so many genes in the dna in 1 chromosome. Sometimes it (remember that different amino acid sequences can still code for the same protein) does, sometimes it does not. Different forms of the same proteins are coded for by different alleles of the same genes this causes variation between individuals o. Mice and humans have the same proteins with slight variations: ex: hemoglobin. A few people have a different allele (1 amino acid difference!) and get sickle: recall that diploid cells contain pairs of homologous chromosomes (with the same, homozygous for a gene: genes, slight variations) cell disease.