Question

Suppose you identify a previously unknown multicellular organism.

a. What composition do you expect its genome to have?


 b. How would your answer change if it were a unicellular organism?


 c. How would your answer change if it were a bacteriophage or virus?

 d.
 Do your answers offer any insights into the origins of cellular organisms?

Answer 1

A. As you questioned: the organism is multicellular hence it must be eukaryote. The genes of eukaryotic organisms are systematically arranged on the chromosomes. The genetic composition of multicellular organism must be DNA. However some bacteria/ virus have genetic materials in forms of RNA. The Dioxyribonucleic carries genetic information in the forms of genes which is made up of exons and introns. Figure 1, is an illustration of eukaryotic cell.

B. unicellular organisms are prokaryotes which have single cell and lack of nucleus. The genetic material is present in the form of nucleoid, in the circular form and do not have cytoplasm. Hence some time it is also known as circular chromosome (eukaryotic chromosome are linear and characterized in different categories like meta-centric, sub-metra centric etc).figure 2, illustrate the structure of prokaryote.

C. phage/ bacteriophage, replicates inside the bacterium. Phase have a genetic material in the form of DNA (eg. T4 page) or RNA ( MS2 phage). Bacteriophage have few genes. Figure 3 structure of phage.

D. the mechanism of evolution of first cell is still unknown and it is hard to experiment it in a lab. But the first cell originated from billion years ago from the primordial ancestor. Unicellular organisms evolved prior to multi cellular organism. At the time when life begun, earth atmosphere had mostly CO₂ and less O₂ and with the help of other gases and sun light as an energy source the first organic molecule was evolved, including several amino acids. This experiment was first demonstrated by Stanley miller in 1950.