Genes, loci and alleles

• The DNA contained within chromosomes is essential for cell survival
• Every?chromosome?consists of a long DNA molecule that?codes for several different proteins
• A length of DNA that codes for a single polypeptide or protein is called a?gene
• The?position of a gene?on a chromosome is its?locus?(plural: loci)
• Each gene can exist in two or more different forms called?alleles
• Different alleles of a gene have slightly?different nucleotide sequences?but they still occupy the?same position?(locus) on the chromosome

Five different genes found at five different loci