Question

1.) Other than their size and their large genome (which approaches the length of that in some small bacteria), Megaviruses also have metabolic genes. What are metabolic genes?

2.) Given the newly found Megaviruses and other viruses harboring metabolic genes, can viruses considered living organisms despite their lack of cells?

Answer 1

1) Metabolic genes are the genes which code for proteins involved in metabolic pathways such as photosynthesis, pentose phosphate pathways, glycolysis, etc. If such genes are present in viruses, it is commonly known as auxiliary metabolic genes since they are not directly in use for metabolism of organism itself. These genes modulate metabolic pathways in host organism infected with the virus. Viruses uses auxiliary metabolic genes to enhance their fitness in host organisms (plants, bacteria, etc.).

2) No, they cannot be considered living organisms since they are not able to grow/divide without infecting suitable host organisms. They don't have metabolic pathways inside thier structure rather they have metabolic genes for better survival in host organisms.