Dominant and recessive genes have different concepts, different properties, produce different substances and are written differently. 1. Concept: A dominant gene is a more energetic allele that can independently determine a specific inherited trait in the offspring, while a recessive gene cannot independently determine the trait in the offspring. 2. Nature: dominant genes can be expressed in both pure and heterozygous genotypes, but recessive genes can be expressed only in pure combinations. 3. Substances produced: recessive alleles are often mutated in the wild type and therefore cannot produce functional substances such as enzymes, whereas dominant alleles can produce functional substances and therefore heterozygotes can also exhibit such functions. 4. Writing: dominant genes are represented by capital letters, recessive genes are represented by lowercase letters. For example, (Xx): X means dominant allele and x means recessive allele.