Answer to Question #128291 in Cell Biology for K. Israel

Question

What if a scientist believes that a virus is alive. How would you address this question: At this same convention your next dilemma is to inform other scientists of multicellular organisms dependency on both Prokaryotes and Protists. Where would you begin? Why would there be no multicellular animals without first Prokaryotes and Protists?

Answer 1

Living things have a number of characteristics that make them qualify to be alive. These include; maintain homeostasis, have different level of organization, they grow, react to stimuli and reproduce.

ü Viruses are assemblies of molecules such as proteins, carbohydrates, lipids and nucleic acids which can do nothing on their own except they enter a living cell. Viruses are unable to multiply without cells, thus they are non-living. Viruses do not have cells but instead a protein coat which protect their genetic material. Viruses do not have the tools to make a copy of their DNA unless they enter a living cell. On the contrary, Mimi virus has been discovered recently to contain tools for making a copy of its DNA suggesting certain types of viruses may actually be living. Generally, viruses are considered non-living.

ü Endosymbiotic theory explains how Multicellular organisms exist because prokaryotes and protists first existed. This theory explains that, organelles like chloroplasts and mitochondria first existed as free-living prokaryotic cells living in larger host cells. The organelles and the host co-existed and merged into a single organism.